3“

1E!
|lv

H

0 I ‘
, . ' , ,' 'I1 (I. l' -‘
1 . ‘ II” ”II I "\ Hi}.
.I' '1' ¢ n‘. ‘ ‘3
I'. . H. ‘L

 

 

114E519

This is to certify that the

dissertation entitled

INVESTIGATION OF HETEROGENEITY
AMONG NEURAL TUBE DEFECTS

presented by

HELGA VALDMANIS TORIELLO

has been accepted towards fulfillment
of the requirements for

 

PhD degree in —Ge-n~e-t—i-es—

Major professp'r J,
i/

. /
/

1/ / L/

MS U is an Affirmative Action/Equal Opportunity Institution 0- 12771

 

 

MSU

LIBRARIES
“—

 

 

RETURNING MATERIALS:
Place in book drop to
remove this checkout from
your record. FINES will
be charged if book is
returned after the date
stamped beIow.

 

 

 

 

 

INVESTIGATION OF HETEROGENEITY

AMONG NEURAL TUBE DEFECTS

By

Helga Valdmanis Toriello

A DISSERTATION

Submitted to
Michigan State University
In Partial Fulfillment of the Requirements
for the Degree of

DOCTOR OF PHILOSOPHY
Department of Genetics

1982

(3 Copyright by
HELGA VALDMANIS TORIELLO

1982

ABSTRACT

INVESTIGATION OF HETEROGENEITY
AMONG NEURAL TUBE DEFECTS

By

Helga Valdmanis Toriello

The goal of this study was to determine whether hetero-
ggeneity exists among the neural tube defects (NTD).
liamilies of children with NTD were sent questionnaires which
tasked about pregnancy history, family history, and other
laackground information (such as blood types and ethnic
origin). The index population was subdivided by defect lo-
cation. These subgroups consisted of index patients with
thoraco-lumbo-sacral defects (T group), lumbo-sacral de-
fects (L group), sacral defects (S group), encephaloceles
(E group), and other defects, including isolated thoracic,
cervical, and thoraco-lumbar defects (0 group). These
subgroups were compared to each other to determine whether
heterogeneity exists (intra-group comparisons). Compari-
sons were also made between index patients and a control
group and index patients and their normal siblings (inter-
group comparisons). Since no differences were found between
the L and S groups and the O and E groups, they were pooled
into two groups.

Significant intra-group differences included a greater

incidence of miscarriage in T and OE sibships as compared

 

Helga Valdmanis Toriello

to the LS group, and a shorter inter-pregnancy gap in the OE
group as compared to the OE group, and a greater incidence
of anti-emetic usage, maternal hormone usage, and concep-
tion following an abotion in the OE group as compared to
the LS group. A number of significant inter-group differ—
ences were found as well. These included a greater inci-
dence of febrile illness and anti-emetic usage in the T
group, a greater incidence of febrile illness and blood
type B and a lower incidence of blood type A and pyloric
stenosis in relatives in the LS group and a greater inci-
dence of abortions in the sibship, anti-emetic and hormone
usage, gynecological problems, shortened inter-pregnancy

gap, and conception following an abortion in the OE group.

ACKNOWLEDGEMENTS

I would like to thank my first chairman, Dr. Janice
Lindstrom, for suggesting this study, and my second chair-
man, Dr. James V. Higgins, for his help and suggestions
throughout the process of data gathering, analysis, and
writing. Other faculty members whom I would like to thank
include the remainder of my committee, Dr. James Asher,
James Potchen, and James Trosho for their suggestions;
Sharon Koehler, MSW, who helped me devise the question-
naire and contacted appropriate families for me, and Dr.
John Gill who gave valuable statistical advice.

My deepest thanks also go to the Spina Bifida Associ-
ation of Michigan, the Spina Bifida Association of
America, and Dr. Mason Barr for their help in obtaining
families affected by spina bifida. Controls were obtained
from the offices of Drs. Struyk, Van Drie and Visscher,
Drs. Newton and Bennett, Drs. Romence, VanderKolk, Klein,
and Riekse and Drs. Federico, Marks and Sprague; to all
the office staff who handed out questionnaires I'm ex-
tremely grateful.

I would also like to thank my excellent and patient
typist, Peggy Wawrzyniak and my mother, Aina Valdmaris,
who gave me hints on completing a PhD and who read my

rough draft and offered helpful comments. Lastly, I'd

iii

 

like to thank both my parents, my sister, my spouse, and my
children for their patience and understanding for the last

six years.

iv

 

 

TABLE OF CONTENTS

ACKNOWLEDGEMENTS . . .

LIST OF TABL

INTRODUCTION

DEVELOP

DESCRIP

THEORIE

ES 0 O O O 0

AND LITERATURE REVIEW

MENT OF THE NEURAL TUBE.

TION OF DEFECTS.

8 OF PATHOGENESIS.

RELATED DEFECTS . .

SEASONAL VARIATION.

SEX RATIO . . . . .

PARITY

ETHNIC

EFFECT

FAMILY

FAMILY

AND MATERNAL AGE

DIFFERENCES IN NTD

OF MIGRATION

INCIDENCE . . . .

HISTORY OF NEURAL TUBE DEFECTS . . .

HISTORY OF OTHER BIRTH DEFECTS . . .

ABORTION INCIDENCE IN SIBSHIPS.

BLOOD TYPE AND HISTOCOMPATIBILITY

ILLNESS

EXOGENOUS HORMONES.

ANTI-EMETICS. . . .

FETAL I

NTERACTION .

MATERNAL FACTORS. .

MATERIALS AND METHODS. .

ANTIGENS.

Page

viii

ll
14
15
18
19
21
23
24
29
32
37
39
41
42
44

46

 

 

TABLE OF CONTENTS (continued)

Page

RESULTS. . . . . . . . . . . . . . . . . . . . . . . . 49
SEASONAL VARIATION. . . . . . . . . . . . . . . . 52
SEX RATIO . . . . . . . . . . . . . . . . . . . . 52
PARITY. . . . . . . . . . . . . . . . . . . . . . 57
SOCIAL CLASS. . . . . . . . . . . . . . . . . . . 57
ETHNIC ORIGIN . . . . . . . . . . . . . . . . . . 57
FAMILY HISTORY OF NTD . . . . . . . . . . . . . . 63
FAMILY HISTORY OF OTHER BIRTH DEFECTS . . . . . . 63
FAMILY HISTORY OF ABORTION. . . . . . . . . . . . 67
BLOOD TYPES . . . . . . . . . . . . . . . . . . . 67
ILLNESS . . . . . . . . . . . . . . . . . . . . . 84
ORAL CONTRACEPTIVES . . . . . . . . . . . . . . . 91
ANTI-EMETICS. . . . . . . . . . . . . . . . . . . 91
HORMONES. . . . . . . . . . . . . . . . . . . . . 95
GYNECOLOGICAL PROBLEMS. . . . . . . . . . . . . . 95
INTER-PREGNANCY GAP (IPG) . . . . . . . . . . . . 95

CONCEPTION AFTER ABORTION . . . . . . . . . . . . 102
ABORTION IN SIBSHIPS. . . . . . . . . . . . . . . 109
FAMILY HISTORY OF BIRTH DEFECTS . . . . . . . . . 109
BLOOD TYPE — ABO. . . . . . . . . . . . . . . . . 109
ILLNESS . . . . . . . . . . . . . . . . . . . . . 109
ORAL CONTRACEPTIVES . . . . . . . . . . . . . . . 116
ANTI-EMETICS. . . . . . . . . . . . . . . . . . . 116

HORMONES. O O I O O O O O O O O O O O O O O O O O 116

vi

 

TABLE OF CONTENTS (continued)

GYNECOLOGICAL PROBLEMS

IPG. . .

CONCEPTION AFTER ABORTION.

DISCUSSION.

SEASONAL VARIATION

SEX RATIO.

PARITY .

ETHNIC

FAMILY

FAMILY

FAMILY

BLOOD TYPES.

ORIGIN.

FEBRILE ILLNESS.

ORAL CONTRACEPTIVES.

ANTI-EMETICS

HORMONE USAGE.

GYNECOLOGICAL PROBLEMS

IPG AND ABORTION PRECEDING

SUMMARY . . .

APPENDIX A:

APPENDIX B:

APPENDIX C:

APPENDIX D:

BIBLIOGRAPHY.

QUESTIONNAIRE

vii

HISTORY OF NTD.

FAMILY HISTORY.

PREGNANCY HISTORY

HISTORY OF ABORTION

CONCEPTION.

BACKGROUND INFORMATION.

HISTORY OF OTHER DEFECTS.

Page
116

121
121
125
125
125
126
128
130
132
134
136
138
139
140
141
142
142
146
149
166
209
226

232

 

Table

10

11

12

13

14

15

16

17

18

19

20

Seasonal Variation in the Incidence of

Sex Ratios observed by other studies

Incidence of

Incidence of Birth Rank of 5 or more

LIST OF TABLES

First-Borns . . .

Ethnic Variation . . . . . .

Types of NTD
Incidence of
Incidence of
Incidence of

Incidence of
Siblings . .

Incidence of

Incidence of

in affected sibs .

NTD in First Degree Relatives
NTD in Second Degree Relatives
NTD in Third Degree Relatives

Isolated Hydrocephalus among

other Birth Defects

Abortion in Sibships

NTD

Page

16

. . 17
. 20
20

26
27

O O O O 28

. . . . 31

Blood Group Distributions from other studies . . . 35

Incidence of Rh- Blood Type in Mothers of NTD
affected Offspring . . . . . . .

Comparisons between Michigan and U.S.

Analysis . .

Monthly Distribution of Births .

Analysis of Monthly Distribution of Births

Sex Distribution . . . . . . .

Analysis of Sex Distribution . .

Data

. . . . 36

l
N

. . . 55

. . . . 56

Proportion of Probands and Siblings which are born
to Primagravidas and Primaparas

viii

O O O O 58

Table

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

LIST OF TABLES (continued)

Analysis of Primaparity and Primagravidity
Effect . . . . . . . . . . . . . . . . . .

Proportion of Mothers who are of Anglo-Saxon
origin 0 O O C C O O O O O O O O O O O O O O O 0

Proportion of Fathers who are of Anglo-Saxon
origin 0 O O O O O O O O O O O O O I O O 0

Analysis of Ethnic Origin Distribution - Maternal
Analysis of Ethnic Origin Distribution - Paternal
Family history of Neural Tube Defects . .
Incidence of other Birth Defects in Siblings . .

Incidence of other Birth Defects in First,
Second, and Third Degree Relatives . . . . .

Incidence of Abortion in Sibships . . . .
Analysis of the Incidence of Abortion in Sibships
Maternal ABO Blood Type Distribution

Paternal ABO Blood Type Distribution . . . . . .
Maternal Rh Blood Type Distribution . . . . . .
Paternal Rh Blood Type Distribution . . . . .1.
Incidence of ABO Blood Type Incompatibility
Incidence of Rh Blood Type Incompatibility

Analysis of ABO Blood Type Distribution -
Maternal O O O O O O O C O O O O O O O O O 0 0

Analysis of ABO Blood Type Distribution -
Paternal O D O I O O O I O O O O O O O 0

Analysis of the Distribution of Blood Type A
Maternal O O O O O O O O O O O O O O O O O O O 0

ix

Page

59

6O

60
61
62
64

65

66

68

7O
71
72
72
73

73

74

75

76

LIST OF TABLES (continued)

Table Page

40 Analysis of the Distribution of Blood Type A -

Paternal I I I I I I I I I I I I I I I I I 77
41 Analysis of the Distribution of Blood Type B -

Maternal I I I I I I I I I I I I I I I I I 78
42 Analysis of the Distribution of Blood Type B -

Paternal I I I I I I I I I I I I I I I I I 79
43 Analysis of the Distribution of Blood Type O -

Maternal I I I I I I I I I I I I I I I I I I I 80
44 Analysis of the Distribution of Blood Type O -

Paternal I I I I I I I I I I I I I I I I I I I I 81
45 Analysis of Blood Type AB Distribution - Maternal. 82
46 Analysis of Blood Type AB Distribution - Paternal. 83
47 Analysis of Rh Blood Type Distribution - Maternal. 85
48 Analysis of Rh Blood Type Distribution - Paternal. 86
49 Analysis of the Incidence of ABO Blood Type

Incompatibility. . . . . . . . . . . . . . 87
50 Analysis of the Incidence of Rh Blood Type

Incompatibility. I I I I I I I I I I I I I I I 88
51 History of Febrile Illness for Two Time Spans. 89
52 Analysis of Incidence of Febrile Illness During

Last Two Months of Pregnancy . . . . . . . . . . 90
53 Analysis of Incidence of Febrile Illness During

Third through Nine Months of Pregnancy . . . . . . 92
54 Oral Contraceptive Usage within Three Months of

or During Conception . . . . . . . . . . . . . . . 93
55 Analysis of Oral Contraceptive Usage within Three

Months of Conception . . . . . . . . . . . . . 94
56 History of Anti-Emetic Usage During Pregnancy. . . 96

 

Table
57
58
59

60

61

62

63

64

65

66

67

68
69
70
71
72
73
74

75

LIST OF TABLES (continued)

Analysis of Anti-Emetic Usaged During Pregnancy.
History of Hormone Usage During Pregnancy. . . .
Analysis of Hormone Usaged During Pregnancy.

History of Hormone—Related Gynecological
PrOblems I I I I I I I I I I I I I I I

Analysis of Maternal History of Gynecological
PIOblemS I I I I I I I I I I I I I I I I I I I I I

Inter-Pregnancy Gap in Months. . . . . . . . . . .

Analysis of Inter— Pregnancy Gap by Monthly
Increments . . . . . . . . . . . . . . . .

Proportion of Conceptions after Abortions among
Probands and Siblings. . . . . . . . . . . . .

Analysis of Distribution of Conception occurring
after Abortion I I I I I I I I I I I I I I I I I

Non-significant Comparisons using Pooled Data -
x2 valueSI I I I I I I I I I I I I I I I I I

Analysis of Pooled Data for Abortion Incidence in
SibShips I I I I I I I I I I I I I I I I I I I

Analysis of Maternal Blood Types - Pooled Data . .
Analysis of Paternal Blood Types - Pooled Data
Analysis of Blood Type A Distribution - Maternal
Analysis of Blood Type A Distribution - Paternal .
Analysis of Blood Type B Distribution - Maternal .
Analysis of Blood Type B Distribution - Paternal
Analysis of Blood Type 0 Distribution - Maternal .

Analysis of Blood Type 0 Distribution — Paternal .

xi

Page
97
98

99

100

101

103

104

105

106

107

110
111
111
112
112
113
113
114

114

 

 

 

 

Table

76

77

78

79

80

81

82

83

84

85

86

LIST OF TABLES (continued)

Analysis of Blood Type AB Distribution — Maternal.

Analysis of Blood Type AB Distribution - Paternal.

Analysis of Pooled

Analysis of Pooled
Usage. . . . . . .

Analysis of Pooled
During Pregnancy .

Analysis of Pooled
Pregnancy. . . . .

Data for Febrile Illness. . . .

Data for Oral Contraceptive

Data for Anti-Emetic Usage

Data for Hormonal Usage During

Analysis of Pooled Data for History of
Gynecological Problems . . . . . . . . . . .

Analysis bf IPG less than or equal to Three
Months - POOlEd Data 0 o o o o o o o o o 0

Analysis of Pooled Data for Distribution of
Conceptions occurring after an Abortion. . .

Primaparity Effect using Index Families for
Determination of Expected Incidence of
FirSt-BOIHS. o o o o o o o o o o o o o o o 0

Proportion of Pregnancies Preceded by an
Abortion I I I I I I I I I I I I I I I I I

xii

Page
115
115

117

118

119

120

122

123

124

129

144

   
 
 

 

 

 

v“ x... s . . . u :- a... .. fl u C. u - . .
.W. . t L. .C . . . . L. g .1. 2.» L.» u.‘ .. n .. ll
. . .\. q . ,.. . a . s . .. .\. z. u s In ~ s . .|:u . . .I.

 

 

 

 

INTRODUCTION AND LITERATURE REVIEW

Many investigations of the embryology, causes, and
distribution of neural tube defects (NTD) have been done.
Most studies have examined anencephaly, iniencephaly, spina
bifida and encephalocele as a homogeneous group of NTD.
Since data exist which suggest that more than one embryo-
logical error can lead to a NTD, it is possible that genetic
heterogeneity exists among the NTD based on these different
pathogeneses. As a result, studies which pooled all NTD
could miss factors significant for only certain NTD. One
possible way of testing whether heterogeneity exists is by
separating the NTD into groups as homogeneous as possible
and then comparing each group to the others in an attempt
to detect genetic or environmental differences. NTD can
be categorized by the location of the defect. Therefore
this thesis examined whether significant differences exist
between the various NTD when separated by the location of
the defect.

Selected parameters were chosen for examination based
on previous findings by other authors. The purpose of the
literature review is to illustrate both the reason for
Choosing certain parameters, and the disagreement among

authors regarding the causes of NTD.

.—v

.‘u

n (

3‘.

'§

\h.

.u.

flahv

 

 

 

DEVELOPMENT OF THE NEURAL TUBE

In the normal sequence of development, the first step
is the formation of the neural plate, which occurs on the
18th day. The neural tube closure begins on the let day.
The inducers for closure are the parachordal mesoderm
(somites and precursors of somites).1

Histologically, closure is the result of differential
contraction at the apical and basal surfaces of the neural
plate cell. Beneath the apical surface of these cells,
there exists a thin band of 40-50 2 microfilaments oriented
parallel to the surface and annularly about the neck of
each cell. These filaments have been compared, structurally
and functionally, to actin by Linville 33 31. in 1972.2
The closure of the neural plate starts in the cervical re-
gion at the level of the fourth through seventh somites.
Anterior closure is completed on the 26th day, and posterior
closure is completed on the 28th day of development. The
last point of closure is at the level of the 25th somite,
which in turn corresponds to the level of the L-l, L-2 ver-
tebral interspace. At twelve weeks gestation, the neuro-
meres correspond anatomically to vertebral segments.3 How-
ever, since the growth of the neural tube slows in the 4th
month, whereas that of the vertebral canal continues at the

same rate, the spinal cord ends at L-l/L-Z and the roots of

the nerves are pulled down to form the cauda equina below

the spinal cord.

 

 

 

 

 

Meanwhile, the neural tube induces formation of the
posterior arches of the vertebrae and the cranial vault.
The part of the somite which will become the vertebral
column is the sclerotome. In the 6th week of gestation,

6 centers of chondrification appear. Two centers are
lateral to the notochord (and will incorporate the noto-
chord to become the centrum), two are lateral to the neural
tube (and will become the neural arch and spinous process),
and two are at the union of the arch and centrum and will
become the transverse processes.4

In the ninth week, ossification begins by the invasion
of pericostal vessels into the centrum. The ossification
centers for the centra appear first in the lower thoracic
and upper lumbar regions, and develop more rapidly caudally
than cranially. Fusion of the lumbar neural arches is com-
pleted between the lat and 7th year, whereas the sacral

arches fuse even later.

DESCRIPTION OF DEFECTS

The term neural tube defects (NTD) refers to a con-
stellation of birth defects affecting the brain and spinal
cord. Included in this category are: (l) anencephaly,
(2) iniencephaly, (3) encephalocele, (4) myelomeningocele,

and (5) meningocele, but not isolated hydrocephalus.

 

 

 

 

 

Defects in Brain and Skull

Anencephaly is the partial or total absence of the
brain. The pituitary gland is absent and therefore the ad-
renal glands are hypoplastic. The calvaria does not develop,
and the frontal, parietal, and occipital bones are partially
missing. In 50% of the cases, rachischisis of the cranium
and vertebrae is present.

When the posterior portion of the skull fails to fuse,
the abnormality is called cranium bifidum. If the meninges,
or brain and meninges herniate through this defect, an en—
cephalocele results. This protrusion is usually covered by
skin, and occurs most often in the occipital region.

Ininencephaly is a developmental defect characterized
by absence of laminar and spinal processes of cervical, thor-
acic, and occasionally lumbar vertebrae, with a reduction in
numbers and irregular fusion of these vertebrae. The brain

and much of the cord often occupy a single cavity.

Defects of Spinal Cord and Vertebrae

Spina bifida is a failure of vertebral arch fusion and
is of two types. When it is not evident externally, it is
called spina bifida occulta (SBO). When it is accompanied
by a herniation of cord or meninges, it is called spina
bifida cystica (SBC). SBC which has meningeal herniation
containing spinal nerve roots is myelomeningocele. A menin-

gocele, on the other hand, does not involve the spinal cord

p..—

L31

.4.
«‘U

pl‘J

:-
‘\v

 

.‘v

 
 

 

 

 

 

 

 

or nerve roots.

Types of spina bifidas which are seen include lumbo-
sacral, cervical, upper thoracic, cervical with upper thor-
acic, and anencephaly with cervical. There are also certain
vertebral defects which are not seen. These include local-
ized thoraco-lumbar, total thoracic, and total cervical
and thoracic spina bifidas.6

Epstein7 noted that 86% of cases of SBC are lumbo-
sacral, 9.5% cervical, and 4.5% thoracic. In a series of
1390 patients, Matson8 had found that 78% were lumbo-
sacral, 10% thoraco-lumbar, 4% cervical and 7% thoracic.

Other spinal cord defects also exist. These include
diastematomyelia, in which the cord is duplicated, syringo-
myelia, in which there is random single or multiple cavity
formation with the cord, and hydromyelia, in which the
spinal cord's central canal is dilated.

Defects associated with, but not affecting the cord
are lipoma, a superficial mass of fat which often extends
to the spinal canal, and dermal sinus, which is any
stratified squamous epithelium-lined depression or tract
extending inward from the skin surface.9 When this tract
is superficial to the sacral fascia and contains hairs, it
is called a pilonidal sinus. When it extends deeper and
c0mmunicates with the dura, it is called a dermal cyst.
This defect may be found anywhere along the spinal cord,

bUt is usually found in the fifth lumbar region.9

 

 

 

 

THEORIES OF PATHOGENESIS

Several theories have been proposed to account for both
the causes of anencephaly and the associations between an-
encephaly and other congenital abnormalities. Perhaps the
simplest and most popular theory proposed to explain anen—
cephaly is the theory of neural tube non-closure put forth
by Von Recklinghausen in 1886.10 In this hypothesis, fail-
ure of anterior neuropore closure results in failure of
induction of surrounding tissues, with the result being the
clinical picture seen in anencephaly.

However, Gardner11

proposed that anencephaly results
from neural tube rupture after closure with the cranial de-
fects resulting from an over-distension of the primitive
brain. This leads to a disruption of the cranial sclerotome
and resultant cranial anomalies. The continuum these anom-
alies form is craniolacuna, cranium bifidum with encephalo-
cele, cranium bifidum apertum with excencephalus, and anen-
cephalus.

12 who has

A third major hypothesis is that of Patten,
demonstrated.that neural tube overgrowth (an excess prolif-
eration of cells) rather than "arrest of development" is
likely to be the cause of anencephaly. He has shown that,
in human anencephalics, plication of the neural tissue

exists, and this plication is the result of the neural

tube's overgrowth. Plication has also been observed in

 

 

 

 

 

animal specimens with experimentally induced neural tube
defects.

Vogel and McClenahanl3 proposed another theory to ac-
count for anencephaly. In fourteen cases, they have dem-
onstrated abnormalities of cerebral arteries. This raised
the question of whether the arterial anomalies were the
cause of the cerebral malformations, or caused by them.

To answer that question, they cauterized arteries in 6 day
old chick embryos and found that 5-7 days later, all the
chicks showed arrested cerebral development. Control chicks
were cauterized in other regions of the body. These chicks'
brains were normal in development. This led to the hypoth-
esis that abnormalities in the vasculature, not neural tube
non-closure, lead to anencephaly.

Theories which have been proposed to account for en-
cephaloceles include the neural tube non-closure theory
(Von Recklinghausen) and the neural tube rupture theory
(Gardner).

However, Caviness 33 31.14 described an infant with an
occipital encephalocele in which the defect appeared to be
secondary to hydrocephalus. They felt that neural tube
non-closure could not be responsible because the defect did
not correspond to the closure line of the neural tube.

Leong gt _1.15 proposed that occipital encephaloceles

result from "breaks" in tissue overlying the mesencephalon,

With resultant migration of brain tissue into a hernia sac.

y
Lu»

.-b
I u

’n
in

.w.
.hL

- Fl

.u\
C.

 

They felt that simple non—closure of the anterior neural
tube was untenable as a hypothesis, since they had observed
well-developed cerebrum and cerebellum in infants affected
with encephaloceles. At 4 weeks, there is normally little
cerebrum or cerebellum, and it would not be expected to
develop if non—closure occurred.

The theories of Von Recklinghausen and Gardner have also
been given as explanations for the pathogenesis of SBC. Ac-
cording to Von Recklinghausen, failure of the posterior
neuropore closure results in SBC. However, Gardner16 noted
that failure of neural tube closure should not lead to
herniation of the meninges. Therefore, he proposed that
rupture of the spinal cord after neural tube closure is the
cause of neural tube defects. He felt that a progressive
distension of the lumen of the entire neural tube is an es—
sential part of the normal embryonic development but that
this phase of development occurs after the neural tube is
closed. This distension of the cord is caused by an accum—
ulation of embryonic cerebrospinal fluid, which eventually
permeates the subarachnoid space.

A dysraphic condition, therefore, represents a morpho-
logical continuum based on varying degrees of distension
at varying times in the developmental sequence. In order
0f severity, these dysraphias are: asymptomatic hydro-
mYEIia, syringomyelia, external hydromyelia with or without

meningocele, diastematomyelia, myelocele, and finally,

Us H
L\ '1'

I:

I1

I. .h\
«N. Is V1

n. 1 e v:

\v. 7v ox» .

1
i2;

2‘
.3.

posterior gut fistula (external rupture of both roof and
floor plates). Gardner cites as evidence for the rupture
theory the observation that in some newborns there exists
a progression caudally of hydromyelia to diastematomyelia
to myelocele. He feels that neural tube non—closure is
insufficient to explain this phenomenon.

Accompanying bony abnormalities could be caused by over-
distension of the neural tube. Supposedly, when the neural
tube over-expands, the transverse plane is moved laterally
with consequent shortening of the longitudinal axis. The
first tissue which is affected is the sclerotomes. It has
been found that the diameter of the developing spinal canal
is determined by the diameter of the nervous tissue it en-
closes. These sclerotomes trophically maintain a certain
prescribed distance from the neural tissue. If the gap is
too wide for closure to occur, then the newly developed
vertebrae may fail to fuse not only posteriorly but an-
teriorly as well.

Although failure of neural tube closure in chicks has
been produced by teratogens (Kalter and Warkany,17 and
Marin-Padilla and Fermla),Gardner feels that this has not
been shown to be the case in humans, citing as evidence
the lack of cases in which both anencephaly and lumbo-
sacral spina bifida both occur.

McCredie19 proposed that injury to neural crest cells

could cause congenital malformations by having a

DD‘

—
In.

”a.

.vi

A

A§a

and
.u a

p?-

Q do
u...

are

at.

1 .
\Jl

 

 

10

theoretical tr0phic quality disrupted. This tr0phic effect
would possibly affect midline, cylindrical, or solid organs;
and if disrupted, a number of defects would result. These
defects include limb anomalies, cleft palate, anal stenosis,
coarctation of the aorta, microphthalmia, anophthalmos,
coloboma, agenesis or hypoplasia of the kidney, liver or
spleen, and spina bifida. Evidence cited by McCredie in
favor of this theory includes the constant histological
finding of sensory ganglion cells within fibrous bands which
appear to be tethering the posterior spinal cord to bony de-
fects in spinous processes. This was discovered in surgi-
cally explored cases of spinal dysraphism. It appears these
bands are damaged sensory nerves, whose injury had led to
prevention of complete fusion of the neural arch, with
either spina bifida, meningocele, or myelomeningocele being
secondary to neural crest damage.

Sever's20 data supported the theory of neural crest
damage. He described a family in which one child had
myelomeningocele, an elder sister had coloboma of the left
eye, and a younger sibling had bilateral, congenital an-
ophthalmia, presumably due to abortive globe formation.

No other family members had birth defects, nor was the
mOther exposed to any known teratogens. Sever hypoth-
eSized that this family represented a case of familial
neural crest cell abnormalities, with the defects repre-

senting differences in embryonal genotypes and

ll

intrauterine environments.

Therefore, there exist a number of theories which attempt
to explain the altered developmental mechanisms responsible
for neural tube defects. If more than one mechanism were re-
sponsible for neural tube defects, then heterogeneity would

be expected to exist for NTD.

RELATED DEFECTS

In addition to the defects of the vertebral column,
other defects are frequently associated with NTD.

David gt 31.21 examined the frequency of other defects
found with anencephaly, and noted that urinary tract de-
fects were most common, with a frequency of 19%. Cardio-
vascular and GI systems were affected in 8%, and genital,
skeletal and other defects were also noted. The most common
single defects were hydronephrosis (8%), and cleft palate
(8%), followed by diaphragmatic hernia (5%), exomphalos
(5%), cleft lip (4%), and horseshoe kidney (4%).

Among defects associated with encephalocele, hydroceph-
alus is most common. Other anomalies such as cleft palate,
Clubfoot, heart defects and congenital hip dislocation have

also been reported (Lorber22

). Clubfoot and hydrocephalus
are also found associated with SBC. Clubfoot occurs when
the cauda equina is damaged by the NTD, resulting in mus-

cular denervation in utero, and ultimately joint

.95

k .-

.L

‘o

12

deformities affecting the lower limbs.

Hydrocephalus associated with SBC is caused by the
Arnold-Chiari malformation, which is a dislocation of part
of the brain into the cervical spina canal. The type of
defect is almost always a type two Arnold-Chiari malforma-
tion, in which there is a tethering effect on the spinal
cord caused by spina bifida cystica, which, in addition to
the adhesions of the cerebellum and posterolateral portion
of the brainstem, serves to displace the brain as far as the
fourth ventricle into the spinal canal down to the fifth
cervical vertebra. The Arnold-Chiari malformation compli-
cates between 60—90% of cases of myelomeningocele.

Although it has been generally accepted that tethering
of the cord in the lumbo-sacral area is the cause of hydro-
cephalus, there have been some findings which contradict
that theory. Cervical spinal nerves have a caudad course
when the Arnold-Chiari malformation is present, which sup-

port the tethering theory; however, Barry t al.24 discov-

ered that in the thoracic area, the course of the nerves
is essentially normal, which contradicts that theory.
Furthermore, hydrocephalus is comparatively rare in sacral
Spina bifida cystica. A ten week old fetus has been ob—
served with myelomeningocele and the Arnold-Chiari malfor-
mation at which time the differential growth of the spinal

cord and vertebral column has not begun.25

13

McLennan26 examined the rib defects in 20 patients with
lumbo-sacral myelodysplasia and found bifid, hypoplastic,
fused, deformed, abnormally spaced or missing ribs. In 19
out of 20 patients, the abnormal ribs were contiguous, and
in 10 out of 20, there were also abnormal thoracic verte-
brae, although the rib and vertebral number did not always
coincide. The authors concluded that defects of the ribs
and lumbo-sacral vertebrae are coincidental, and that they
are the result of a teratogen acting in a single period as
opposed to the rib defects being secondary to the vertebral
defects.

In a larger study of 434 patients with SBC, Van Went

et 1.27 noted that the average number of associated defects,

both skeletal and non-skeletal, was 2.08 for male patients
and 2.33 for female patients. More than 82% of their
patients had one or more associated anomalies. Among
patients without any additional malformations, a greater
proportion were male. However, the only significant finding
was that females had a greater incidence of skeletal anoma-
lies than did males (p‘.001).

Other research on NTD has focussed on the epidemio-
logical data, in an attempt to identify causes of NTD.

Data gathered in one locale may show significance, but

invariably, data gathered in other locales contradict it.

 

l4

SEASONAL VARIATION

Seasonal variation in the incidence of NTD is an impor—
tant indicator that environmental factors play a role in the
cause of NTD. Differences are frequently found between 10-
cales, as well as between the peaks of anencephaly and spina
bifida within the same locale.

Carter28

noted a low incidence of spina bifida cystica
births occurring in May through July, whereas the anen-
cephaly low occurred in March through May, two months
earlier. Carter explains this discrepancy by stating that
the gestations of anencephalic fetuses tend to be only
seven months as opposed to the normal nine. However, the
peak in anencephalic births (Dec.-Feb.) occurred one month
later than the spina bifida births' peak (Nov.-Jan.).
Therefore, the anencephalic conceptions had to have occurred
three months later than conceptions of spina bifida af—
fected infants if Carter's contention is correct. This
would mean that different events may have caused the peaks
in spina bifida births than caused the peak in anencephaly
births . Usually, anencephalics are postmature, unless the

29 Therefore, in a

pregnancy is complicated by hydramnios.
particular season, the times of conception could vary from
30 to 45 weeks prior to the birth.

In Belfast, Elwood 3; 31.30 found that for the time

Period of 1956-60, the spina bifida incidence was higher

 

 

15

from January-June, whereas from July-December, the anen-
cephaly incidence was higher.

In other studies (Williamson,31 Silberg gt 31.32

Czeizel 35 £1.33

), one type of defect showed seasonal vari-
ation whereas the other types did not. In Williamson's
study, anencephaly had a peak incidence in January-March.
Czeizel gt 31. and Silberg £3 31. each noted a significant
seasonal variation for spina bifida births, but not for en-
cephalocele or anencephaly. All other studies included en-
cephaloceles with spina bifidas.

In summary, there seem to be indications from the
studies that anencephaly and spina bifida, and where ex-
amined separately, encephalocele and spina bifida have
different seasonal patterns, indicating that there could be

heterogeneity between these defects. See Table l for a

summary of the data.

SEX RATIO

Data has also been gathered regarding the sex ratio,
Which usually significantly differs from unity. Almost all
Studies agree that the majority of anencephaly and spina
bifida affected individuals are females 28’31’33’37’38’42

(See Table 2). However, in a study which examined encepha-

locele separately from spina bifida, it was found that the

 

l.- Fl

;-2

o H

~§<\!

I<2Ai

HI (\

.lll

l6

msamam maaam was samsamuamaa I mm<«

 

 

 

 

as I haamcommmm manadaoo .uaum .ummmlhash .ooQI.uoo .cmc<
He mo. va madmaowmmm .smoImmwuamum mashI.ua< .quI.uuo .cmo<
Ha I maamcommmm oaumuso manhI.um< .usz.smh .amc<
Hq moo. we >Hamaommom omnmnc moahl.ua< .umZI.:Mh .ao:<
Ha I hHHmaommmm .GmUImmaauHumz .ummthash .umZI.:mh .am:¢
oq Ho. vm >H£ucoa amvmsm I .uQMmI.um< mm
as Hoo. va . hasucoa commam I .amhl.>oz .soa<
mm I %Ham:aGMIfiamm vcmawsm I I Mm
um I hasucoa Husommwz osahl.un< .umnl.uoo .namoam
mm 0H. vm hanuaoa Huaommaz manhI.um¢ .umnl.uoo mm
mm I AHnuooa Husommwz .umzl.omh .ummmlhash .smc<
mm I madmaommmm HmmumH I I mmm
mm I manuaoa vcmawam .w54Imaah .amhI.>oz mm
mm I manuooa vamHmsm mashI.um< .nomI.uon .cmc<
um I I xuo» 3oz I I mm<
on I manuaoa mauwmwz .Hm<l.umz manhIhmz mm
mm I manages monuma .m I .usz.ams mm<
om I maamaommom ummmaom .omnl.uoo .usz.QMH mm
on I zaamaommmm ummmamm maahI.um< .ummmI%H=h .cmo4
mm I manuaoa humwcam I I .smmosm
mm Hoo. va >Hnuaoa humwasm .umomlhash .HQ<I.nmm mm
mm I hanuaoa hummosm I I .am:<
Hm I madmaommmm vanawsm I I mm
Hm I maamcommmm wamawam I .umZI.amh .oma<
cm I haamsommwm mmamz I .ooalhaah «mm<
vow: moamvaoaH wosmcfiocH
moosoumwmm moamoamacwwm mooamfl>fia mamoog anaaaaz aaawxmz uumwwo
992 no mozmnHqu may zH onHmHm<> A<zom<mm

H m4m<H

 

 

 

 

 

 

 

17

TABLE 2

SEX RATIOS OBSERVED BY OTHER STUDIES

Z MALE PROBANDS

 

 

 

Anencephaly Encephalocele Spina Bifida Reference
25% 47% 28
26% 39% 31
44% 42% 38
29% 41% 42
27% 39% 37

32% 49% 42% 33

18

that the sex ratio was not different from the controls

(48.6% males being affected).33

PARITY AND MATERNAL AGE

Conflicting reports exist for the effect of parity and
maternal age on incidence of NTD, although there seems to be
general agreement that the first-born has a higher risk than

the second born (Carter gt gt.28 Williamson,31 and Czeizel

al.33 34

gt Laurence, and Carter gt gt.43). Some authors
have observed U-shaped risk curves31’33’ 34 while others have
noted linearly increasing risks with parity.38 Table 3 sum-
marizes the findings.

Parity is unavoidably entangled with maternal age.
Czeizel gt 21-33 found that the first-born has a higher risk
of being affected with a NTD, and that the risk rises as the
mother gets older. Leck44 stated that in North America the
incidences among first-borns are higher than those among sub-
sequently born infants only if the mother is over age 35.

Other authors have also noted that incidences are
highest among infants born to mothers less than twenty
years.28’41’ 42 In one study,45 the primaparity effect was
more marked among young mothers than older mothers.

33 found that whereas mothers of anencepha-

Czeizel gt gt.
lics who are 20-24 are more numerous than expected, mothers

of encephalocele affected infants are more likely to be

 

 

 

19

over 35 years of age. They also noted that paternal age was
significant for encephalocele, but not anencephaly.

The conflicts in the data have been partly resolved by
1.46

Elwood gt who found a U—shaped risk related to both
parity and maternal age. However, they stated that the an-
encephaly incidence is not related to maternal age, but de-
creases with an increasing number of live births and increases
with the number of previous stillbirths or abortions.

Czeizel gt gt.33 noted a U-shaped risk for parity in the
encephalocele group, and a decreasing rate with increasing

parity in the A and SB groups. Tables 3 and 4 summarize the

data.

ETHNIC DIFFERENCES IN NTD INCIDENCE

Ethnic origin also influences one's risks of having a
child with a NTD. Ireland, Northern and Western Britain,
Alexandria, Egypt, and some Sikh communities have the
highest frequencies known. Northeastern North America and
the Middle East have rates greater than 1/1000, whereas NTD
are rare in Yemenites, Iraqis, and Iranians.

In all studies, Negroes had lower incidences of NTD
than did Caucasians (3/10003nu Caucasians, .88/1000 ~é
Negroes). When partitioned according to the type of de-

fect, the anencephaly rate in Negroes was found to be

20

 

 

 

 

 

 

 

 

 

Hm Nw NoH No
on Na Noa Nm No
mN Na NOH Nw
as Nmm mom
mm NHN Nam NmN
mmmmm mmmmmmm mamuouammmuzm «nHmHm «szm wqammmuzmza unzamomm zH Hummus
mac: mo n so mmz<m mamHm H4 muzmaHozH
s mgm<a
Hm Nam Nmm New .
mm Nms Nmm Now New
mm Nos Nos Nms
as Nmm Non
mm Nma Nmu NmN
mmmmm. mmmmmmw mgmuoqammmuzm <nHmHm «szm wg<mmmuzmza "ozamomm zH Bowman

 

 

mZMOmIHmmHm so mozmnHozH
m mun<a

21

one sixth of the Caucasian's rates whereas the spina bifida
rates were equal.47

The incidence of encephalocele, however, remains fairly
constant, being around 1/10,000 in most populations examined,

48

and occurring usually in the occipital region. One excep-
tion is in Thailand, where an unusually high incidence of
fronto-ethmoidal encephalocele has been noted.49 (See

Table 5 for a summary of the findings).

EFFECT OF MIGRATION

Indicative of genetic factors is the finding that some
migrants retain the incidence of areas from which they came.
For example, Indians living in Fiji have a higher incidence

50 Other migrants

of anencephaly than do native Melanasians.
have lower incidences than their fatherland, but higher than
their adopted homeland. For example, Australians from
England and Bostonians from Britain demonstrate this pat-
tern.

51

However, Elwood t 1. demonstrated that the inci-

dences of anencephaly among mothers of British and French
origin were the same in Canada, although the incidence rates
in the two countries are different (2-3/1000 in Great Bri—
tain; .5/1000 in France). The incidences among mothers of
Other ethnic origins were lower, and more closely resembled

the incidences in their native countries. Since these

groups had migrated to Canada later than did the French

22

 

 

m «HHmhhmsa H. o.H o.H
so shame I s. m.
ms muu=UHmu I s. N.
ms «HeaH .z I w.s m.N
mm «UHhma .m I mm.H mm.H

Ns.sN.Hs «Humez so. m. N.
Ho Chasm I w.m N.H
mm HmmhmH I om. s.
mm Hummus: NN. H.H ms.H
oh themsm I I NN.
am. mud—mum I m. I
NN tosaoH mH. Hs.H qm.H
am mmHmz m. o.m H.s
om ummNHmm I N.s m.s
mm «Huoom «>02 I m.H I
He onsmtshm smz I mm.H I
mm umhmsa I as.H NN.H
HG GNSwSUumemm I on. I
Hm .Hoo .uHhm I s. I
om samHmH muons NH. mN.N mH.N
mm mcHHohmo .m I s. I
an msoH I I NN.
mm show smz I m.HIH m.HIH
Nm mmumum sthas NH. as. s.

mosmummom mamooq .ocfi mHoooamsmmosm .oaa hamnmmonmc< moamvfioaH 0mm

 

 

Awsmmsonu moav mocmvfiocH

m mqm<H

 

ZOHH<HM<> onmHm

1d

a

«In
II.

nrt

23

and British groups, the authors concluded that incidences

in ethnic groups depended on time of migration.

FAMILY HISTORY OF NEURAL TUBE DEFECTS

Other epidemiological data has been gathered on the fre—
quency of NTD in family members. It is evident that the risk
of having a child with a NTD is dependent on the number and
relationship of affected family members. The incidence of
NTD among siblings of anencephalics is between 1.8 and 4.9%,
and among siblings of spina bifida affected probands the in—

33

cidence ranges from 2.7 to 6.1%. Czeizel gt gt. did not
find any affected siblings of encephalocele affected pro—
bands; the only affected relative of all first, second and
third degree relatives (N=1288) was an uncle. However,
Lorber gt gt.22 found the recurrence of NTD was 6% in sib-
lings of probands with encephalocele. Only one sibling of
356 also had an encephalocele, whereas ten had myelomeningo—
cele (level unspecified), seven had anencephaly, and two had
"other" NTD (including one with spina bifida occulta). In

the data of Carter gt gt.28

, individuals identified as having
encephaloceles had a total of 94 siblings, with two having
spina bifidas, and three having anencephaly, for an inci-
dence of 5.6%.

Early studies have suggested that siblings of NTD af—

fected individuals were as likely to have anencephaly as to

 

24

43 Czeizel e gt.33 Pen-

have spina bifida (Carter gt gt.

rose65); more recent studies have found that siblings tend

to have the same type of defect as the proband (Cowchock
t 21-66 67).

Richards gt a1.

Overall, among affected sib-
lings the chances are 2:1 that the same type of defect will
recur. Table 6 summarizes the findings.

In addition to siblings having an increased incidence
of NTD, parents also have a greater incidence of spina
bifida (anencephaly of course not being an option). Carter
and Evans68 found that 3% of parents of NTD affected indi-
viduals were themselves affected. Affected fathers had
more affected offspring than did affected mothers. Three
percent of half-siblings sharing the same mother as compared
to 1% of half-siblings sharing the same father had NTD in the
same study. Other studies have found incidences between .8
and 2.6% for half-siblings. Among other second degree rela-
tives, incidences between 0 and 1.2% have been reported;
among third degree relatives, incidences range between .25
and 2.6%. (See tables 7-9). Pooling all of the studies,
the incidence among second degree relatives, excluding half-

siblings, is .36% and among third degree relatives .51%.

FAMILY HISTORY OF OTHER BIRTH DEFECTS

Although isolated hydrocephalus is not generally be-

lieved to be related to NTD, a number of studies have found

 

 

 

25

 

so om0H\mN oon\s

«N Nms\mm Nms\NH

ma mom\HH mom\ON

so omNH\sm omNH\NN

NH mNH\s mNH\H

oN «mo\OH «ms\N

mo N¢N\m NAN\N

No oms\mH omq\o

mm smm\m amm\o

ms smw\Nm smm\oN

mN omN\mH omN\NH

we Nsm\N Nom\m

Hm mHH\s mHH\H <aHmHm «szm

so mom\H moM\mH

an wNN\m mNN\m

wN Nmm\mH wa\oN

NH omH\m omH\m

on Nwm\N Nwm\m

«N oo\H om\o

mo Nm\N Nm\N

No sms\w sms\mH

mm omH\q owH\m

ms moN\mH moN\oH

mN smN\NH smN\sN

Hm Hs\o Hs\N wH<mmmuzmz<
mozmmmmmm a\mm mHHz mmHm a H\wH<mmmuzmza maHz mmHm * azamomm zH Bowman

 

 

mmHm QMHUmmm¢

o mqm<H

ZH QHZ mo mmmwa

mm I No

 

 

26

 

 

mm I No.m
mm I No.o mHmooamnamoam
mm I Nm.w
we I No.N
me I NH.©
mm I Nq.m
we Nm.a Nm.~
Hm I Nm.m I msHHHm maHam
mm I Nw.m
me I NH.¢
mm I N~.m
Hm I Nm.¢
we I Nm.¢ mamsmwocmc<
Hm I HmN\mv NmH Hmm<v
mm I Ham0H\mHv Nm.H msHmHm maHam
\hamnamoamom
wcfiummmmo mwcaanfim
mocmuwwmm Ga uomwwm Qz<momm zH Hommmn

 

mm>HH<Amm mmmwmn HmmHm ZH QHZ mo mozmnHozH

m mqde

27

 

 

 

 

mm I AHo~\Hv Nm. I oamuoamnnmocm
«H I nHmHH\mv No. I
mm I AmoHH\mv NN. I
me I I No
mm I I No.m
Hm I HmHs\mv NH. I msHmHm maHam
sH I HNHNHHV Hm. I
mm I Amcoa\mv “N. I
me I I No
mN I I NN.H HHmnamoamt<
Hm I I I
as I HoHHHHHV NH. I
mH Abom\av NM. I NN
NH I HNHs\mv Hm. I
mm I I Nm. mm<
msonam: mam mmomfic mmaoss mam mucus mwcaanfimlmams
monouomom aw summon Qz<momm zH Hommmn

 

mm>HH<Amm mmmuma onomm ZH QHZ mo mozmnHUZH

m mam<8

 

INCIDENCE OF NTD

28

TABLE 9

IN THIRD DEGREE RELATIVES

 

DEFECT IN PROBAND

Defect in Cousins

Reference

 

 

 

A88 .4% (1/239) 73
.7% (13/1899) 60
Anencephaly 2.6% (4/156) 31
3% (3/1129) 28
5% (ll/2164) 43
3% (3/1119) 33
.8% (13/1898) 74
Spina Bifida .9% (4/423) 31
4% (6/1360) 28
7% (17/2474) 43
3% (8/2330) 33

29

an increased incidence among siblings of NTD probands. The
highest frequency was .7%, or 9/1256 sibs of SBC probands
affected with isolated hydrocephalus (Lorber69). Table 10
summarizes the findings of other studies.

Pooling all of the studies, the overall incidence of hy-
drocephalus in siblings of ASB affected probands was .24%,
which is 2-4 times the population frequency (.05% Bergsma7
or .1% Warkanyaa).

When other birth defects were considered, Czeizel and
Williamson found no increases in the incidence of other birth
defects in the families and sibs respectively. Carter and
Evans69 noted that among 354 sibs of index patients, 3 had
congenital heart defects and one had pyloric stenosis.
Richards gtgt.67 found a three-fold increase in the inci—
dences of both congenital heart defects and oral clefts among
siblings. Table 11 summarizes the findings. Only cleft lip
and cleft palate is significantly increased, since the inci-
dence among siblings was almost three times the population
figure. Congenital heart defects were more difficult to
evaluate since the figures for population frequencies vary
so widely (4/1000, Warkany48, 8/1000, Behrman71, and lO/lOOO

Bergsma70).

ABORTION INCIDENCE IN SIBSHIPS
Mothers of a child with a NTD may be at a higher risk

of spontaneously aborting a pregnancy than mothers in the

 

 

30

TABLE 10

INCIDENCE OF ISOLATED HYDROCEPHALUS AMONG SIBLINGS

 

 

 

 

 

DEFECT IN PROBAND: Incidence N/T Reference
Anencephaly/Spina 'i%§ 2i;9;94 79
Bifida ° ° 5 9 33
.40% 5/1263 56
Total: .232% 27/11636
.36% 1/278 74
.14% 1/708 43
.27% 2/754 28
0% 0/238 31
.17% 1/582 76
Anencephaly 0% 0/88 69
.84% 1/119 80
.56% _ 5/887 78
0% 0/454 67
.24% 1/423 59
Total: .26% 12/4531
0% 0/432 74
0% 0/854 43
0% 0/730 28
0% 0/80 31
Spina Bifida .7% 9/1256 69
.15% I/654 76
0% 0/166 80
.22% 2/903 78
0% 0/450 67
Total: .22% 12/5525
Grand Total: .235% 51/21,692
Expected: 10.846-21.692
2

Significance: X = 39.638, p (.001

 

31

 

 

 

ucmowwwcwfim no: u mz «
no. «a no. oh
mz NHm.m u Nx aHo.m u Nx «mz "teamUHmHanm
NN.IH. NH. NmH. NHIH. “smuumhxm
Nmo. NHH. NNN. Nat. "hostsHocH
NNNs\s NNNHNH NNNH\NH NNNNHHN "Htuoe
cameo
oHH\H mHHNN NNONHN «NHHNH
NOHHNN NNOHNH NsHH\m NHOH\N NsHH\N NNOH\N NHsH\OH omsHNOH “mHmuoH
NN omHNN smHHO omHHN smH\H omHNH smHNH omH\N smHNm
NH NNNNH NHN\H Nms\H NHN\H NNHNH NHN\H NHHHH NHNNH
Hm HmHNH HHHNH HmHNH HmH\H
Ho som\o HONNO NOHHH omHNH ems\q
mm mHn\o mHmHO mHm\H mHm\m
mo NHNNO smNHH sNNNH sHNNN
mma mma mma mm< washout
mm a mm 4 mm H mm a :H shaman
mosmumwmm uoomnaao mfimocmum owuoahm Ado uummm uommmn

 

HH mHmae

HH\zV meommma mHmHm mmmeo mo mozmaHozH

32

general population. McDonald noted that the abortion risk
was 3.5% higher in NTD families than in controls. She found
that the abortuses in NTD sibships tended to occur earlier
in the pregnancy order, as did NTD births, and unlike abor-
tions in control sibships. This lent support to the hypoth-
esis that those abortions are of affected fetuses.

Most of the conceptuses with a NTD are lost prior to
birth. Creasy82 found that 75% of NTD conceptuses are not
born alive. Those lost at an early gestational age usually
had encephaloceles, whereas those lost later usually had an-
encephalies. This means that 5% of all conceptions have ASB.

It has also been found that among women with a history
of two or more previous miscarriages, irregardless of the
number of living children, the incidence of spina bifida in
the children was significantly higher, whereas the incidence
of anencephaly was not.83

Other authors have not noted an excess of abortions in
the families of NTD children, although some did not have
control data, and others used general population data ob-
tained from that data of Warburton and Fraser.84 Table 12

summarizes the findings.

BLOOD TYPES AND HISTOCOMPATIBILITY ANTIGENS
Blood type antigesn and histocompatibility antigens and
their relationship to NTD has been investigated. Coffey85

found a higher incidence of blood type 0 in mothers of

33

TABLE 12

INCIDENCE OF ABORTION IN SIBSHIPS

 

 

Defect in Proband

 

Anencephaly Spina Bifida Control Reference
ASB
25.1% 25.3% none 74
14.7% 16.2% 13% 67
16.2% 16.8% none 43
11.0% 8.9% none 28
16.3% 17.4% 15%* 31
22.0% 15.7% 15%* 58
11.7% 10.7% 7.5% 76
15.6% 12.1% 80

 

* General population data

34

anencephalics; this has not been found by others. Baker and
Sherry86 noted a significant incidence of Rh- mothers in
cases as compared to controls. Czeizel gt gt.33 also found
the increased incidence of Rh- mothers, but only in spina
bifida group and not in the encephalocele and anencephaly
groups. Carter gt gt.28 found no significant difference for
ABC or Rh, although he and others found that the incidence of
Rh- mothers was higher among index groups (see Table 13).

Golding87 noted that the greater incidence of Rh-mothers
among index patients could be attributed to a dramatic in—
crease only in mothers whose spina bifida child was the third
pregnancy or later. This indicated to him that Rh isoimmuni-
zation could be etiologically significant. Table 14 summa—
rizes the data.

Studies have examined the possible role of HLA in NTD
etiology. Neither linkage studies nor examinations of asso-
ciations between certain HLA types and NTD have shown a re—

91’ 92 However, one study de-

lationship between the two.
serves mention because of its demonstration that genetic
heterogeneity among NTD is possible.

Schacter gt gt.93 examined the incidence of HLA compat-
ibility in couples who had either had a child with a NTD,
had repeated pregnancy losses, or had three or more children
with no abnormalities and no history of spontaneous abor-

tions. They found that the percentage of couples sharing two

or more antigens was significantly higher in couples having

35

 

qu.ma
Naq.aq
wa.qq

AOMHZOU

NH.OH
N~.Hm
NH.HH
No.Hq

AOmHzoo

No.mm
Nm.mm

Nm.nm

mqmooa<mmmuzm

emu u z
NN.OH
Nm.qq
Nm.mq

wd¢mmmuzmz¢

oma u z
Nw.w
NN.HN
No.0N
Nq.mq

wd<mmmuzmz<

mom n z
Nm.qH
Nu.am
Nm.oq

<QHmHm <szm

NwH n z
Nm.¢
No.5m
NN.¢H
Nm.mm

<loHm <szm

Qz<momm ZH Hommmn

Ill

.wm.flm um umuumo Boom
m< + m
d
o

mmWH nooqm

.mm.mm.WM Homamuo Scum
m<
o
m
4

mme oooqm

 

 

mMHQDHm Mmmeo 20mm mZOHHDMHMHmHQ moomw QOOAm

ma m4m¢fi

36

TABLE 14

INCIDENCE OF Rh- BLOOD TYPE
IN MOTHERS 0F NTD AFFECTED OFFSPRING

 

 

 

% mothers Rh- Control Reference
15.5 15.0 80
18.8 17.0 88
25.0 14.8 33
17.8 16.0 43
18.5 17.0 90
22.6 17.2 89

32.1 15 85

 

37

two or more pregnancy losses (at similar gestational age) or
a child with a NTD not compatible with life, g.g., anen—
cephaly. This implied to the authors that only in certain
cases of recurrent abortions or NTD was HLA compatibility a

significant etiological factor.
ILLNESS

Research into the role of illness in the etiology of NTD
has also been conducted by several investigators. In a study
of influenza A and NTD, Doll94 noticed a sharp rise in the
number of stillbirths attributable to anencephaly during the
same years as an Asian flu epidemic. Wilson and Stein95 did
a retrospective study in which flu titers were measured in
mothers of anencephalic children and mothers with normal chil-
dren. They found that 2/200 mothers with positive titers had
anencephalic children, as compared to 0/188 with negative
titers. The significance of these findings was unknown, al-
though the authors concluded that flu may be occasionally
associated with anencephaly. Coffey and Jessop96 found that
34% of mothers having children born with NTD had influenza
during the first trimester of pregnancy. In that same study,
they noted that the incidence of NTD was 1.2% in the index
group; in controls it was .9%. Similarly, Kleinebrect gt
gt.97 did a prospective study of the incidences of various

birth defects, including NTD, in mothers having flu or

febrile (fever producing) illnesses in the first twelve weeks

38

of pregnancy as compared to controls (unaffected mothers).
In the index group the incidence of NTD was .77%, whereas in
controls it was .5%. They reported that they found no sig-
nificant correlations between any single anomaly and history
of illness. The authors concluded that whereas fever is un-
likely to be the primary cause of malformations, it may have
a role in the multifactorial model of birth defects.

Kurent47 prospectively examined the role of intra-
uterine infection in the etiology of NTD. The three methods
were: (1) drawing serial maternal serum specimens during
pregnancy, (2) determining levels of cord-serum IgM, and
(3) analyzing epidemiological variables. Using serial serum
specimens, the authors tested for influenzas A, B, and C,
Reovirus, Mumps, ECHO 6, Respiratory synctitial, Herpes,
Cytomegalic, Rubella, and several Coxsackie B viruses. No
increase in the incidence of infection was noted among
mothers who delivered infants with NTD as compared to mothers
having normal infants.

Miller gt gt.98 examined 63 pregnancies which resulted
in the birth of an anencephalic. Eleven percent of the
mothers had a history of hyperthermia (sauna bathing or
tfebrile illness) near the time of anterior neuropore closure.
Only .1% of controls had such a history. The authors con—
cluded that 10% of anencephalies are caused by hyperthermia.

Chance and Smith99 questioned 43 mothers who had had a child

with a spina bifida at a level of L-5 or higher; of these,

39

3 had had episodes of hyperthermia at the time of posterior
neuropore closure. Controls, which were relatives of the
mothers, had no episodes of hyperthermia. Halperin and
Wilroy100 detected 3/45 NTD births with histories of hyper-
thermia, including one nasal encephalocele and flu, one
thoraco—lumbar myelomeningocele and pharyngitis, and one en-
cephalocele and sauna. The incidence of hyperthermia in
controls was zero.

James101 cast doubt on the hyperthermia hypothesis by
pointing out that winter conceptions are not affected as
frequently as other conceptions, even though flu frequency
is greater in winter; and that areas of high incidence of
NTD have little correlation with hyperthermia producing oc-

currences. Rapola et 1.102 reported a low incidence of NTD

in Finland (.32/1000 for anencephaly) although more than a

million families enjoy sauna bathing (10-30 minutes at

70-100 degrees C.).

EXOGENOUS HORMONES

Exogenous hormones have been reported as possibly
causing NTD. A general study of 149 mothers who had deformed
infants, including 70 with NTD, revealed that 23 had had hor-
mones administered as a pregnancy test in the first tri—
mester, as compared to 8 of 149 controls. The authors con—
cluded that since hormones during pregnancy caused birth

defects, such pregnancy tests should be avoided.103

40

Prospective studies regarding the use of oral contracep-
tives and birth defects had noted no significant differences
in incidences of birth defects between control and index
groups (Rothman gt gt.104, Ortiz-Perez gt gt.105). Kasan and
Andrews106 demonstrated that although the overall incidence
of birth defects was not different between the index and con—
trol groups (2.83% vs. 2.95%), the incidence of NTD was sta-
tistically significant, being greater in the index group
(.63% vs. .25%). Furthermore, only anencephaly and spina
bifida, but not encephalocele or iniencephaly were greater
in incidence.

Since the index group included women who had stopped
taking oral contraceptives three months or less prior to con-
ception, it is possible that oral contraceptives are not ter-
atogenic in themselves, but rather cause some physiologic
disturbance which is teratogenic. It is known that oral
contraceptives cause vitamin and mineral imbalances, which
is significant in light of the recent findings implicating
vitamin deficiences as being etiologically involved in NTD.
Smithells gtgt.107 showed that the recurrence risk of NTD
among vitamin supplemented women was .6%, as compared to
5% among unsupplemented women. All of the women were se-
lected from a group who had previously had one or more chil—
dren affected with NTD.

Among the nutritional imbalances caused by oral contra-

ceptives are elevations in serum vitamin A levels, and

 

 

 

 

 

41
decreases in zinc, vitamin C and folate levels.108 All of
these have been implicated in some way in the etiology of
NTD. Cohlan gt gt.109 found that hypervitaminosis A pro-
duced exencephalies and spina bifidas in rates. Warkany gt

al.110

demonstrated that CNS deformities were produced in
rats whose mothers were fed zinc deficient diets for a short
term period. In humans, Tunte111 found an inverse correla-
tion between ascorbated levels and incidence of anencephaly,
and Hibbard and Smithells112 found a significant relation-

ship between NTD and defective folate metabolism in the

mother.

ANTI-EMETICS

Walker113 reported five families in which Bendectin had
been given in early pregnancy. In the first family, the
mother started taking anti-emetics four weeks after the last
menstrual period. The result of the pregnancy was an inien-
cephalic. In the second family, the proband had inien-
cephaly, the oldest sibling had a defect of L—5 and the
sacrum and the third child had a SEQ of S-l. The second
cousin also had iniencephaly, and the mother of that child
had cervical spine anomalies. Both mothers had excess
vomiting during those pregnancies for which anti-emetics were
prescribed. In the third family, thoracic defects were noted
in the proband. The level was not noted in the proband of

the fourth family. In the fifth family, the proband had

42

iniencephaly, a paternal cousin had a thoracic myelomenin-
gocele, and a maternal cousin had a lumbosacral myelomenin-
gocele.

Prospective studies, however, have yielded negative re-
sults. Yerushalmy and Milkovich114 found no instances of NTD
among 330 women receiving anti-emetics during the first tri-
mester. Similarly, Pettersson115 noted no instances of NTD
among 292 women who had been treated with meclizine.
Smithells and Chinn116 found one instance of anencephaly in
offspring of 219 mothers taking anti-emetics during pregnancy.
However, in a recent study by Cordero gt gt.117, an associa—
tion between encephaloceles and Bendectin usage was found; no
association was found between other NTD and Bendectin. This
study coupled with the case reports by Walker imply that

anti-emetics may be significant in the etiology of some, but

not all NTD.

FETAL INTERACTION

Knox118 speculated that NTD are caused by the interac-
tion between fetuses, either co-twins or preceding pregnan-
cies. He first proposed that a NTD was the result of an
interaction between twin fetuses, with one twin being lost,
and the other affected with a NTD. He postulated the exis-
tence of a diallelic gene locus on the X chromosome, with
alleles being S and T, and possible genotypes being SS, ST,

and TT for females and SY and TY for males. A NTD would be

43

caused by the twin which possesses the allele which the other
twin doesn't possess attacking the co-twin and causing its
abortion. The attacker twin would then be left with a NTD.
For example, in an ST/SY pair, the male twin would be aborted
and the female twin left with a NTD. This theory also in-
cluded sequential fetus-fetus interaction as a possible etio-
logical event. This was supported by his finding that the
mean pregnancy interval was noted to be less for infants born
with NTD than for normal infants. Record gt gt.76 as well
found that the mean pregnancy interval was shorter for pro-
bands than controls.

Rogers119 further expanded the hypothesis by stating
that a previous abortion may also influence the next preg-
nancy so that a NTD occurred in that pregnancy. The residual
trophoblast (rest) from the abortion would somehow become ac-
tivated during the second pregnancy, and a mosaic placenta
formed. However, the cellular elements derived from the pre-
vious trophoblast might be at an inappropriate stage of
maturity, thus disrupting the timing of embryological events.

Clarke gt_a_t.120 found that a significantly larger
number of miscarriages and stillbirths occurred before an
affected proband than after (p .001), thus supporting the
hypothesis. Further support came from the findings of
Arias-Bernel gt gt.121 and Weisli122 who each found XX cell
lines in male anencephalics.

Contrary to this theory, however, are Clarke gt gt.'s120

 

 

 

44

finding that there was no significant difference in the mean
time interval between an affected or normal child and the im-
mediately preceding miscarriage. Further, Roberts and

Lloyd123 found an inverse relationship between the frequency

of miscarriages and NTD in S. Wales. Elwood124 found that

25% of the cases of NTD are among the firstborn.

MATERNAL FACTORS

Among maternal factors investigated include the role of
fertility in NTD etiology. Knox118 reported that pregnancies
induced by clomiphene resulted in a high frequency of infants
born with anencephaly. Ahlgren125 reported a prospective
study of 159 pregnancies induced by clomiphene; of the 148
infants which were liveborn, 8 had major malformations in-
cluding one memingocele. The expected number of major malfor-
mations was 4-5, or half that of the observed number of mal-
formations. Since neither the clomiphene dosage nor the
number of treatments given before pregnancy markedly affected
the outcome, the authors felt that the malformations were due
to an underlying subfertility, and not to the clomiphene.
Wynne-Davies39 found that among mothers who had children with
spina bifida, half had a history of irregular periods, long
periods of infertility, menorrhagia, severe dysmenorrhea, or
other menstrual disorders.

Elwood126 disagreed with the subfertility hypothesis by

comparing the dizygotic twinning rate with anencephalic

 

 

 

 

 

45

rates, which he felt were positively correlated. Since

mothers of dizygous twins are more fertile, and have more

pregnancies than other mothers, the correlation was puzzling.

The correlation between twinning rates and NTD would be ex—

pected to be negative if mothers of anencephalics were sub—

.fertile. Therefore, he suggested that dizygotic twinning and

ariencephaly were related, and that clomiphene acted via a

mezchanism which increased the risks for both, notably by in-

dtlcing twinning, which would lead to twin-twin interaction.

It is apparent from the preceding discussion that a

Wtsalth of data has been gathered and a number of theories

plroposed regarding the causes of NTD. It is also apparent

ttlat many contradictions exist, and there are few consisten-

cies between the different studies.

This study was an attempt to demonstrate that the NTD

arre really a heterogeneous group, based on different embry-

0143gical malfunctions. These malfunctions could be of at

lxaast two types, most notably neural tube non-closure and

rueural tube rupture. These, in turn, could have different

genuetic bases and environmental causes. The main questions

aSked by this thesis were whether such heterogeneity exists,

and if so, if it can be detected by separating the NTD by

location and comparing these homogeneous groups among them—

selves. Heterogeneity would be confirmed if there were sig-

nificant differences found between the groups.

MATERIALS AND METHODS

The index group consisted of families in which one or
more children were affected with a NTD. These defects in-
cluded meningocele, myelomeningocele, and encephalocele.
Anencephaly was not included because only four families could
be ascertained. Families were selected from several sources,
including the Spina Bifida Association of Michigan's mailing
list, genetics clinics rosters, and private physicians.

These families were sent questionnaires which included
questions about family genetic history, pregnancy history,
and other background information. The family history section
contained questions about incidences of other family members
with NTD, hydrocephalus, scoliosis, and other "back problems",
with the type to be noted. There were also questions which
dealt with family history of other birth defects, most
notably those which are also thought to have a multifactorial
cause, including pyloric stenosis, Clubfoot, congenital heart
disease, and cleft lip and/or palate. There was also a nota—
tion to list individuals with Down Syndrome.

In the pregnancy history section, questions were asked
about use of oral contraceptives, anti-emetics, hormones,
fertility drugs, "other medication" (with a note to specify),

history of any illness or vaccination during pregnancy,

46

history of gynecological problems, and length of time for
conception to occur. The person filling out the question-
naire was also asked to note which of the mother's other
pregnancies had any of those factors during the pregnancy.
Family history of miscarriage and stillbirth was also ob—
tained.

Lastly, questions were asked about ethnic origin, con-
sanguinity, blood types of both parents, and whether or not
back X-rays had been taken of either parent and the results.
Information regarding the total number of first, second,
and third degree relatives to the proband and sexes of sib-
lings were also obtained.

Controls were obtained from a sample of private obste-
tricians' patients filling out the same questionnaire. These
were matched to the proband from the index family according
to parity and family size.

Medical records were requested on the proband and the
mother, as well as other affected family members. The rec-
ords on the proband were used in determining the type of NTD,
and level when possible. The mother's medical records were
used to verify pregnancy and gynecological problems. If
records were not available on the proband, then the family
was contacted and asked to describe the location of their
child's lesion, as well as the child's abilities and which
functions were affected. If the family's description of the

child's function corresponded well to the location

48

mentioned, then the child was included in the study.
Additional data was obtained from spina bifida parents
groups around the country (U.S. data). Families which con—
sented to participate were sent a questionnaire which was
modified to include a request for information regarding the
location of the defect and their child's abilities. Subse-
quently families were included who could describe adequately
the level of the lesion and which was corroborated by the de—

scription of the child's function.

RESULTS

The index patients were divided into nine groups, five
from the main group of data (Michigan data) and four from
the U.S. data. These were:

A. Michigan data

1. Thoracic level, including lumbo-sacral involve-
ment

2. Lumbar level, including sacral involvement

3 Sacral level

4. "Other" level, including cervical, mid-thoracic,
and mid-lumbar lesions

5. Encephaloceles

B. U.S. data

1. Thoracic level, including lumbo-sacral involve-
ment

2. Lumbar level, including sacral involvement

3. Sacral level

4. "Other" level, including cervical, mid-thoracic,
and mid-lumbar lesions

Initial comparisons were made between the same level in
the Michigan and U.S. groups to determine whether the two
groups of data could be pooled. The variables examined were:

Seasonal variation

Sex ratio

Parity

Ethnic origin

Family history of NTD
Family history of other birth defects
Number of sibs aborted
Blood type distributions
ABO and Rh incompatibility
Illness during pregnancy
11. Oral contraceptive use

12. Anti—emetic usage

13. Hormone usage

\OGDNO‘U'IbLDNI—I
I

H
O
I

49

50

14. Gynecological problems

15. Inter—pregnancy gap (IPG)

16. Result of pregnancy preceding the birth of the proband
No significant differences were found between the two groups
at any vertebral level, so the two bodies of data were com-
bined for the thoracic, lumbar, sacral and other levels.

See Table 15 for results of the comparisons.

The five groups were then compared to each other for
each variable to test for heterogeneity. Comparisons were
thoracic (T) versus lumbar (L), T versus sacral (S), T
versus other (0), T versus encephalocele (E), L versus S,
and so on. Comparisons were also made between each group
and controls, and where possible, between probands and sibs
within each group. Therefore, the comparisons made con-
sisted of inter-group data (between index patients and con-
trols or sibs), and intra—group data (between vertebral
levels).

The statistical method used was the X2 analysis, unless
otherwise noted. When the expected number in a cell was

less than five (in 2 x 2 contingency tables), Yates correc—

tion factor was applied.

51

 

 

 

TABLE 15

COMPARISONS BETWEEN MICHIGAN AND U.S. DATA - x2 VALUES

LEVEL

VARIABLE EXAMINED T L s 0
SEASONAL VARIATION o1 3.581 .331 .331
SEX RATIO .60 1.38 O 0
ABORTIONS 2.90 2.39 .30 0
PARITY 3.43 .50 .21 3.63
A30 BLOOD TYPE — MATERNAL .362 6.942 .612 .222
ABC BLOOD TYPE - PATERNAL 2.812 4.142 .502 3.712
RH BLOOD TYPE - MATERNAL 1.26 .49 .45
RH BLOOD TYPE - PATERNAL .41 O
ABO INCOMPATIBILITY 2.57 2.39 .49
RH INCOMPATIBILITY 0 .36 .50
FEBRILE ILLNESS 1.82 0 .39 .62
ORAL CONTRACEPTIVES 2.06 .89 0 .61
HORMONES .41 2.16 .56 0
ANTI—EMETICS .14 .19 .35
GYNECOLOGICAL PROBLEMS 1.41 0
INTER-PREGNANCY GAP o3 03 03 .553
CONCEPTION POST ABORTION .30 .56 .34
ETHNIC ORIGIN 3.36 .15 0 0
1

11 degrees of freedom
23 degrees of freedom
38 degrees of freedom

All others, one degree of freedom

52

SEASONAL VARIATION

In order to determine whether there was any seasonality
in the distribution of births of probands, the monthly inci-
dence of births was compared to the State of Michigan data
on monthly birth incidence between the years 1965—79. The

NTD versus control comparison was not significant, with a

2
x11

to the control group or their siblings, no significant dif-

of 12.253. When the five levels were compared separately

ferences emerged. Similarly, none of the intra-group com-

parisons were significant. Tables 16-17 summarize the data.

SEX RATIO

The proportion of males and females in each group and
siblings of each group is given in Table 18. Although there
was an apparent excess of female probands in three of the
five groups, when the pooled NTD group was compared to the
control group, the difference was not significant. When the
index groups were separated by level, there were no signifi-
cant differences noted both for inter-group and intra-group
comparisons.

Since there were fewer males in the families of thoracic
level probands in general, the index group and sibling group
were pooled and compared to the control group. The differ-
ence was not significant, with a X2 of 2.2 (p> .05). Table

19 summarizes the statistical analyses performed.

53

 

OH H o N N H N o o o H o H M

NH 0 N H N N m H H N m H o o

«N H N N m H c N m N N H H m

HmH NH mH w «H m MH m HH «H N N m H

mm H m m o m N a N N m m H H
“No mnHm

NmH.m Nam.N NHm.m NMN.w wa.w wa.w NoN.w qu.w NNm.N Noq.w NHo.N Nmo.w "mocowHoaH

 

Houusoo
N o o o H o H o o o o o o m
m H o N o o N o o o N o H o
mH H H H H H N m o H N H H m
mN N CH N H 0 OH N 3 m N m m H
0N H N N m N e m N H o N N H
asouw
z .009 .>oz .uoo .umom .w:< NHsh wand Nmz .um¢ .umz .nmm .amm " mezoz

 

 

mmHMHm mo ZOHHDmHMHmHQ meHZOZ

0H mHm<H

ANALYSIS OF MONTHLY DISTRIBUTION OF BIRTHS

54

TABLE 17

 

 

 

Comparison X2 Significance
NTD vs. control 12.023 NS
I vs. control 8.750 NS
L vs. control 10.178 NS
S vs. control 3.702 NS
0 vs. Control 12.490 NS
E vs. control 13.094 NS
I vs L 8.340 NS
I vs. S 6.490 NS
T vs. 0 14.539 NS
T vs. E 3.320 NS
L vs. S 4.530 NS
L vs. 0 12.950 NS
L vs. E 9.265 NS
S vs. 0 3.000 NS
S vs. E 5.818 NS
0 vs. E 2.083 NS
T vs. sibs 12.17 NS
L vs. sibs 6.28 NS
S vs. sibs 3.33 NS
0 vs. sibs 1.38 NS
E vs. sibs 1.60 NS

 

55

TABLE 18

SEX DISTRIBUTION

 

 

 

Group Number of Number of N
males females
T 11 18 29
L 52 52 104
S 9 13 22
0 4 9 13
E 4 3 7
Sibs of:
T 10 18 28
L 63 53 116
S 16 9 25
0 6 10 16
E 4 7 7
COntrols 31 32 63

 

 

ANALYSIS OF SEX DISTRIBUTION

56

TABLE 19

 

 

 

Comparison X2 Significance
NTD vs. control .227 NS
T vs. control 1.018 NS
L vs. control .048 NS
S vs. control .451 NS
0 vs. control 1.474 NS
E vs. control 0
T vs L 1.325 NS
T vs. S .047 NS
T vs. 0 .010 NS
T vs. E .179 NS
L vs. S .601 NS
L vs. 0 1.712 NS
L vs. E 1.471 NS
8 vs. 0 .015 NS
S vs. E .010 NS
0 vs. E .004 NS
T vs. sibs .141 NS
L vs. sibs .408 NS
8 vs. sibs 2.506 NS
0 vs. sibs .143 NS
E vs. sibs .005 NS

57

PARITY

The proportion of probands which were born to prima-
gravidas and the proportion born to primaparas are given in
Table 20. There was no primagravidity or primaparity effect
noted in either the inter-group or intra-group comparisons.
Since the index group had been matched to the control group
by parity, state statistics were obtained which indicated
that 33.7% of all births between 1960-1979 were first-borns.
This was used as the control value. See Table 21 for a

summary of the results.

SOCIAL CLASS

Social class as a variable was not examined. However,
care had been taken to obtain controls from private obste-
tricians' offices, and since all of the index patients also
had private obstetricians, the social class effect was hope-
fully lessened by excluding clinic patients from the control

group.

ETHNIC ORIGIN

The data was divided by whether mother was of Anglo-
Saxon origin or father was of Anglo-Saxon origin. No sig-
nificant differences emerged in either the NTD vs. control,
inter-group or intra-group comparisons. Tables 22-25 sum—

marize the data.

58

 

 

mN Nm.MH « Nw.mH « m
Nm No.HN w NN.mN HH 0
mN Nm.Nm HH NN.Hm mH m
wwH Nw.mN om NH.mm «o H
mm NH.«N «H Nm.Nm NH 9
"mo mnHm
N Nm.N« m N¢.N« m m
mH NN.@« N NN.©N « o
NN Nm.o« N N«.om m m
00H Nm.H« m« Nw.mm mm H
om Nm.m« MH NN.om HH 9
unmouom possum unmouoa Honaso
z mommamsHum on open mmvH>muwwaHum cu anon msouo

 

 

m<m<m<2Hmm Qz< m¢QH><MO¢ZHmm OH zmom mm< moHIB mozHHmHm 92¢ maz<momm mo

ON MHm<H

ZOHHmomomm

 

59

 

mz mNN. woo. Houuaoo .m> m
mz mmo. NoH. Houucoo .m> 0
m2 NH«. mom. Houuooo .m> m
mz wNo. ooH. Houucoo .m> H
mz wNo. mmw. Houucoo .m> H
mz HNN. moo. Houueoo .m> nHz
mz NNo. NNo. m .m> 0
m2 moo. moo. m .m> m
mz woo. oNo. o .m> m
mz m«H. Noo. m .m> H
mz mw«. mmH. o .m> H
mz moo. oHo. m .m> H
mz Noo. o m .m> H
mz om«. m«o. o .m> H
mz o moo. m .m> H
mz moo. N«o. H .m> H
OOGMOHHHame NuHoH>muwmaHua How Nx NuHumamaHuo How NN somHumoaoo

 

 

HUMhmm wHHQH><MO<ZHMm 924 MHHm¢m<EHmm Mme mo mHmWH<Z¢

HN HHH<H

60

TABLE 22

PROPORTION OF MOTHERS WHO ARE OF ANGLO-SAXON ORIGIN

 

 

 

Group Anglo-Saxon Other

T 8 18 26
L 7 65 82
S 3 15 18
O 0 13 13
E 3 4 7
C 5 29 34

 

TABLE 23

PROPORTION OF FATHERS WHO ARE OF ANGLO-SAXON ORIGIN

 

 

Group Anglo-Saxon Other

 

bl—‘I—‘J—‘wm

18
65
14
11

32

26
78
18
12

36

 

61

TABLE 24

ANALYSIS OF ETHNIC ORIGIN DISTRIBUTION - MATERNAL

 

 

 

Comparison X2 Significance
I vs. control 2.239 NS
L vs. control .275 NS
8 vs. Control .034 NS
0 vs. control .873 NS
E vs. control 1.411 NS
T vs. L 1.117 NS
T vs. S .501 NS
I vs. 0 3.321 NS
I vs. E .392 NS
L vs. S .004 NS
L vs. 0 2.023 NS
L vs. E .764 NS
S vs. 0 .871 NS
S vs. E .739 NS

0 vs. E 3.623 NS

 

62

TABLE 25

ANALYSIS OF ETHNIC ORIGIN DISTRIBUTION - PATERNAL

 

 

 

Comparison X Significance
T vs. control 3.737 NS
L vs. control .599 NS
3 Vs . control .458 NS
0 vs . control .074 1 NS
E VS . control .058 NS
T vs . L 2.402 NS
T vs . S .442 NS
T Vs . O 1.214 NS
T vs . E 1.009 NS
L VSI. S .046 NS
L Vs.. 0 .098 NS
L V8 . E .026 NS
3 Vs . 0 .250 NS
3 Vs. E .199 NS

0 Vs. E .166 NS

63

FAMILY HISTORY OF NTD

The incidence of NTD in siblings, second degree relatives
(half—sibs, aunts and uncles and nieces and nephews) and third
degree relatives (cousins) is given in Table 26. The inci-
dence in siblings was highest in the sacral group, and lowest

in the encephalocele group. The types of defects in siblings

 

were:
GROUP DEFECTS IN SIBS
T 1 anencephaly
L 3 lumbosacral
l sacral
S 1 lumbosacral
1 sacral
0 l anencephaly

no affected sibs
None of the differences between the index groups were sig—
nificant, nor between the pooled index groups (NTD group) and

controls.

FAMILY HISTORY OF OTHER BIRTH DEFECTS

The incidence of hydrocephalus, congenital heart disease,
clubfoot, pyloric stenosis and cleft lip and/or palate in
first, second, and third degree relatives is shown in Tables
27 and 28. The only significant difference was that there
were fewer than expected relatives affected with pyloric
stenosis in the lumbar group; for the other groups as well
the number of expected individuals was greater than the ob-

served number, although the difference was not significant.

 

64

 

 

No omHHO No Nm\o No H\o H
No mmN\o Nm.H HmHH NN.« «NHH o
NHm. mmm\N No NNHHQ Nm mN\N m
NmH. NSON\N No. oNo\« No.N NmH\« H
No «mSHO No «SHHQ No.N SNHH H
nmaummma nmaummm< nmaummm<
moZmnHozH mmmzaz mozmaHozH mmmzaz muzmaHozH mmmzpz gnome
mmmoma amHmH mmmomn nzoomm mozHHmHm

 

 

MHommmn MHDH H¢Msz mo wmoamHm wHHS<m

0N mHm4H

65

 

 

HHo. NNo. woo.

Iooo. o OHo. o «mo. o IHHo. o I««o. o HH m
HNo. N«o. on.

ImmHo. o Nmo. o «mo. 0 HNo. o I«wo. H HN o
mNo. no. N.

ImNHo. o wmo. o oH. o ImNo. o IH. o mN m
m«H. omN. ooH.H

INNo. o mHN. o owm. o Im«H. o Iowm. m m«H H
mmo. wNo. NHm.

ImmHo. o mmmo. o omH. o Immo. o IomH. o mm H
.axm .mno .axm .mno .axm .mno .mxm .mno .axm .mno mnHm mo N asouo

msHmnmmoouon m\H uHOHu OHNOHNH uOOHHDHo uummm

 

 

mUZHHmHm ZH mHommmn mHMHm MmmHo

NN MHm<H

mo MUZMQHOZH

66

Ho.v a .owm.s I N

 

 

N «

o«N. «mo. moo.H
IMNH. H o«N. 0 «mm. o INm«. o I«wm. H o«N m
mmm. NHN.N «N«.«
IoNN. o mmm. N NHN.N o IoOH.H N INHN.N m mmm o
ONm. wa.H wo«.N
Imo«. o on. o «oN.m o Ion. m I«oN.m m on m
woo.« oNH.m «oN.Nm
I««o.N o woo.« N NNmm.oH o Iwwo.« m INmm.oH mH mmo« H
omN.H NN«.N www.m
IwHo. o omN.H N I««o.« H IomN.H « I««m.« N oMNH H

.oxo .mHo .oxm .mno .oxo .mno .axo .mno .oxm .mno z macho
msHmnomoouon m\H uNOHu .amum OHHOHNH uoomnsHo uummm

 

 

mm>HH<Hmm mmmwmn QmHmH Qz¢ .onumm .HmmHm ZH mHUmme mHmHm mmmHo mo mozmmHozH

wN MHH<H

67

FAMILY HISTORY OF ABORTION

Tables 29 and 30 summarize the data and analyses of the
numbers of total pregnancies aborted in each group. Whereas
no significant difference between all NTD and controls was
found, when the levels were examined separately, a number of
significant differences emerged. The O and E groups each had
a greater incidence of abortions in sibships than did L, S or
control groups. The thoracic group also had a greater inci—
dence of abortions than did the lumbar group. These compar-
isons demonstrate definite heterogeneity between the enceph—
alocele and other groups on the one hand, and the lumbar and
sacral groups on the other hand. There was also heteroge-

neity demonstrated between the thoracic and lumbar groups.

BLOOD TYPES

A summary of ABC and Rh blood type distributions and in-
cidence of incompatibility at the two loci appears in Tables
31-36." The distribution of A, B, AB and O phenotypes in
both parents of the NTD group was significantly different
than the control distributions. When partitioned and com-
pared to each other and to controls, significant differences
were found between mothers of L and 0 group probands and
controls, and fathers of L and S group probands and controls
for ABO blood type distribution (see Tables 37 and 38). To
examine the nature of these differences, the data was put in
the form A vs. not A, B vs. not B, 0 vs. not 0, and AB vs.

not AB (Tables 39-46 summarize the analyses). It was found

68

TABLE 29

INCIDENCE OF ABORTION IN SIBSHIPS

 

 

 

Group Number of abortions Number of liveborns N
T 19 39 58
L 36 152 188
S 4 25 29
O 16 21 37
E 9 10 19

 

69

TABLE 30

ANALYSIS OF THE INCIDENCE 0F ABORTION IN SIBSHIPS

 

 

 

Comparison X2 value Significance
NTD vs. control 1.327 NS
T vs. control 3.069 NS
L vs. control .085 NS
S vs. control .676 NS
0 vs. control 7.346 p‘-.Ol
E vs. control 4.966 p4..05
I vs. L 4.730 p< .05
T vs. 8 3.576 NS
T vs. 0 1.067 NS
T vs. E 1.320 NS
L vs. S .479 NS
L vs. 0 10.100 p< .01
L vs. E 6.505 p< .02
S vs. 0 6.676 p< .01
S VS. E 6.552 p< .02
0 vs. E .086 NS

 

 

70

:oHushHhuhHs OHHD solo om< no

 

 

mmHocosomum coHumHsmom no woman .umnsoa omuomoxm u .mxm«« .umnasa ow>uomno u .mnot

m«o.m « NMN. o wmm. o mNH.m m m

omo.o « oN«. m oNH.H H me.o o o

mNm.o m on. H ooN.H m NoN.o o m

mmN.mm om «mN.N o «ow.o oH NON.om mN H

o««.oH m on. N oHo.N N mNN.oH NH H
.axm .mno .oxm .mp0 .oxo .mno **.oxw «.mno macho
o m< m H mme GOOHH

 

 

ZOHHDHHMHmHQ mme DOOHm om< H¢ZMMH<Z

Hm MHH<H

71

 

 

mNH.N N oNH. H oN«. o mMN.N N m
oNN.m « wo«. H woo.H m «om.m « o
oom.o m ««m. H ««m.H « NmH.N m m
www.om om «H«.N m «oo.m NH NmN.Hm «N H
moN.w m o«o.H H oom.H m mo«.m o B
.oxo .mno .oxm .mno .oxm .mno .mxm ..mno macho
m< m < mme QOOHH

 

 

ZOHHDHHMHmHQ mme OOOHH om< H<ZMMH¢A

Nm_MHm<H

72

TABLE 33

MATERNAL RH BLOOD TYPE DISTRIBUTION

 

 

 

 

 

 

 

 

Rh positive Rh negative N
Group obs.* exp.* obS. exp.
T 19 20.40 5 3.60 24
L 62 66.30 16 11.70 78
s 11 11.90 3 2.10 14
o 10 11.90 4 2.10 14
E 7 5.95 0 1.05 7
Controls 39 34.85 5 6.15 41
TABLE 34
PATERNAL RH BLOOD TYPE DISTRIBUTION
Rh positive Rh negative N
Group obs. exp. obs. exp.
T 14 15.30 4 2.70 18
L 52 54.40 12 9.60 64
S 12 10.20 0 1.80 12
O 10 10.20 2 1.80 12
E 5 4.25 0 .75 5
*obs. = observed number, exp. = expected number based on a

population frequency of 15% for Rh negative blood type in-
cidence

73

TABLE 35

INCIDENCE OF ABO BLOOD TYPE INCOMPATIBILITY

 

 

 

 

 

 

 

Group. Observed incidence Expected incidence
T 10/19 (52.63%) 11.55/19 (60.79%)
L 45/68 (66.18%) 41.34/68 (60.79%)
S 10/14 (71.43%) 8.51/14 (60.79%)
0 9/12 (75.00%) 7.30/12 (60.79%)
E 3/5 (60.00%) 3.04/5 (60.79%)

TABLE 36
INCIDENCE OF RH BLOOD TYPE INCOMPATIBILITY

Group Observed incidence Expected incidence
T 6/18 (33.33%) 4.59/18 (25.5%)
L 15/61 (24.59%) 15.56/61 (25.5%)
S 2/11 (18.18%) 2.81/11 (25.5%)
0 4/12 (33.33%) 3.06/12 (25.5%)
E 0/5 (0%) 1.28/5 (25.5%)

 

74

TABLE 37

ANALYSIS OF ABO BLOOD TYPE DISTRIBUTIONS - MATERNAL

 

 

 

Comparison X2 value Significance
NTD vs. control 22.572 p< .001
T vs. control .76 NS

L vs. control 21.12 p< .001.
S vs. control 3.234 NS
0 vs. control 13.983 p< .01
E vs. control 1.79 NS
T vs. L 4.567 NS
T vs. S 1.214 NS
T vs. 0 1.327 NS
T vs. E 2.018 NS
L vs. S .323 NS
L vs. 0 3.850 NS
L vs. E 2.586 NS
S vs. 0 2.024 NS
S vs. E 2.07 NS

 

75

TABLE 38

ANALYSIS OF ABO BLOOD TYPE DISTRIBUTION - PATERNAL

 

 

 

Comparison X2 value Significance
NTD vs. control 23.39 p (.001
T vs. control 2.14 NS
L vs. control 10.81 pc .02
S vs. control . 8.09 p< .05
0 vs. control 5.428 NS
E vs. control 4.89 NS
I vs. L .157 NS
T vs. S 1.623 NS
T vs. 0 .359 NS
T VS. E .326 NS
L vs. S 1.610 NS
L vs. 0 1.054 NS
L vs. E 1.773 NS
S vs. 0 .561 NS
5 vs. E 2.092 NS

0 vs. E 1.890 NS

 

ANALYSIS OF THE DISTRIBUTION OF BLOOD TYPE

76

TABLE 39

A - MATERNAL

 

 

X2 value

 

Comparison Significance
NTD vs. control 4.86 NS
I vs control .27 N5
L vs control 7.27 p< .01
S vs. control .14 NS
0 vs control .02 NS
E vs control .01 NS
T vs. L 4.859 [><.05
T vs. S .370 NS
T vs. 0 .181 NS
T vs. E .111 NS
L vs. S .352 NS
L vs. 0 .594 NS
L vs. E .139 NS
S vs. 0 .024 NS
S vs. E .034 NS
0 vs. E 0 NS

 

77

TABLE 40

ANALYSIS OF THE DISTRIBUTION OF BLOOD TYPE A - PATERNAL

 

 

 

Comparison X2 value Significance
NTD vs. control 6.69 p<..01
I vs. control 1.32 NS
L vs. control 3.42 NS

S vs. control 4.34 p< .05

0 vs. control .62 NS

E vs. control .043 NS
T vs. L .033 NS
T vs. S .227 NS
T vs. 0 .010 NS
T vs. E .126 NS
L vs. S 1.385 NS
L vs. 0 .001 NS
L vs. E .080 NS
S vs. 0 .194 NS
S vs. E .138 NS

0 vs. E .068 NS

 

78

TABLE 41

ANALYSIS OF THE DISTRIBUTION OF BLOOD TYPE B - MATERNAL

 

 

 

Comparison X2 value Significance
NTD vs. control 9.52 p<..01
I vs. control .0002 NS

L vs. control 13.59 p( .001
S vs. control 1.33 NS
0 vs. control .027 NS
E vs. control .64 NS
T vs. L 1.667 NS
T vs. S .332 NS
T vs. 0 .017 NS
T vs. E .621 NS
L vs. S .0005 NS
L vs. 0 .581 NS
L vs. E .619 NS
S vs. 0 .156 NS
S vs. E .368 NS

0 vs. E .566 NS

 

79

TABLE 42

ANALYSIS OF THE DISTRIBUTION OF BLOOD TYPE B - PATERNAL

 

 

 

Comparison X2 value Significance
NTD vs. control 15.72 p4..001
T vs. control .56 NS
L vs. control 6.68 p« .01
S vs. control 3.92 p< .05
0 vs. control 2.40 NS
E vs. control .025 NS
T vs. L .014 NS
T vs. S .165 NS
T vs. 0 .080 NS
T vs. E .037 NS
L vs. S .159 NS
L vs. 0 .059 NS
L vs. E .135 NS
S vs. 0 0 NS
S vs. E .347 NS

0 vs. E .285 NS

 

80

 

 

 

TABLE 43

ANALYSIS OF DISTRIBUTION OF BLOOD TYPE 0 - MATERNAL
Comparison X2 value Significance
I vs. control 1.012 NS
L vs. control .029 NS
S vs. control .631 NS
0 vs. control 1.270 NS
E vs. control .120 NS
T vs. L .939 NS
T vs. S 0 NS
T vs. 0 .085 NS
I vs. E .486 NS
L vs. S .638 NS
L vs. 0 1.234 NS
L vs. E .063 NS
S vs. 0 .077 NS
S vs. E .114 NS
0 vs. E .631 NS

 

81

TABLE 44

ANALYSIS OF BLOOD TYPE 0 DISTRIBUTION - PATERNAL

 

 

 

Comparison X2 value Significance
T vs. control .115 NS
L vs. control .051 NS
S vs. control . .275 NS
0 vs. control .505 NS
E vs. control .025 NS
I vs. L .019 NS
T vs. S .024 NS
T vs. 0 .158 NS
T vs. E .069 NS
L vs. S .003 NS
L vs. 0 1.012 NS
L vs. E .156 NS
S vs. 0 .778 NS
S vs. E .401 NS
0 vs. E .068 NS

 

82

TABLE 45

ANALYSIS OF BLOOD TYPE AB DISTRIBUTION - MATERNAL

 

 

 

Comparison X2 value Significance
T vs. control .594 NS
L vs. control 2.834 NS
S vs. control .487 NS
0 vs. control 8.909 p( .01
E vs. control .246 NS
T vs. L .022 NS
I vs. S .036 NS
T vs. 0 .428 NS
T vs. E .360 NS
L vs. S .010 NS
L vs. 0 1.346 NS
L vs. E .556 NS
S vs. 0 .376 NS
S vs. E .418 NS

0 vs. E .437 NS

 

83

TABLE 46

ANALYSIS OF BLOOD TYPE AB DISTRIBUTION — PATERNAL

 

 

 

Comparison X2 value Significance
T vs. control .201 NS
L vs. control 1.877 NS
S vs. control .395 NS
0 vs. control .021 NS
E vs. Control .663 NS
T vs. L .180 NS
T vs. S .016 NS
T vs. 0 .115 NS
T vs. E .023 NS
L vs. S .067 NS
L vs. 0 0 NS
L vs. E .005 NS
S vs. 0 .045 NS
S vs. E .002 NS

0 vs. E .463 NS

 

84

that mothers of the lumbar group probands were significantly
less often of blood type A when compared to controls or the
thoracic probands' mothers and significantly more often of
blood type B when compared to controls. Mothers of the 0
group probands were significantly more often of blood type
AB. Fathers of the sacral group probands were significantly
less often of blood type A when compared to controls and
fathers of both lumbar and sacral groups probands were more
often of blood type B when compared to controls.

Rh blood type was not found to be significantly differ-
ent in either NTD vs. control or inter group and intra-group
comparisons. Similarly, neither ABO nor RH incompatibility
were found to be significantly different in any of the com-

parisons. Tables 47—50 summarize these analyses.

ILLNESS

Two time spans were considered in the analysis of the
effect of illness. These were the first two months, and the
third through ninth month of pregnancy (see Table 51). A
significantly greater number of mothers in the NTD group re-
ported having a febrile illness during the first two months
as compared to the control mothers. (X2 = 14.14, p‘ .001).
However, when the groups were analyzed by level, only the T,
L and S groups were significantly different from controls.
When probands were compared to their siblings.in each group,
only the T and L versus sib comparisons were significant,

(see Table 52). When history of illness during the third

85

TABLE 47

ANALYSIS OF RH BLOOD TYPE DISTRIBUTION - MATERNAL

 

 

 

Comparison X2 value Significance
NTD vs. control 3.18 NS
T vs. control .64 NS
L vs. control 1.86 NS
S vs. control .46 NS
0 vs. control 2.02 NS
E vs. control 1.23 NS
T vs. L .001 NS
T vs. S .002 NS
T vs. 0 .021 NS
T vs. E .541 NS
L vs. s .008 ' NS
L vs. 0 .103 NS
L vs. E .684 NS
8 vs. 0 .190 NS

3 vs. E .438 NS

0 vs. E .960 NS

 

86

TABLE 48

 

 

 

ANALYSIS OF RH BLOOD TYPE DISTRIBUTION — PATERNAL
Comparison X2 value Significance
NTD vs. control .076 NS

T vs. control .74 NS
L vs. control .71 NS
S vs. control 2.12 NS
0 vs control 026 NS
E vs. control .88 NS
T vs. L .108 NS
I vs S 1.435 NS
T vs. 0 .158 NS
T vs. E .244 NS
L vs. S .063 NS
L vs. 0 .029 NS
L vs. E .206 NS
3 vs. 0 .545 NS
S vs. E 0 NS
0 vs. E .021 NS

 

87

TABLE 49

ANALYSIS OF THE INCIDENCE OF ABO BLOOD TYPE INCOMPATIBILITY

 

 

 

Comparison X value Significance
NTD vs. control .982 NS
T vs. control .530 NS
L vs. control .826 NS
S vs. control .665 NS
0 vs. control .503 NS
E vs. control .001 NS
T VS. L 1.171 NS
T vs. S 1.192 NS
T vs. 0 .558 NS
T vs. E .075 NS
L vs. S .045 NS
L vs. 0 .072 NS
L vs. E .079 NS
S vs. 0 .042 NS
S vs. E .222 NS

0 vs. E .001 NS

 

88

TABLE 50

ANALYSIS OF THE INCIDENCE OF RH BLOOD TYPE INCOMPATIBILITY

 

 

 

Comparison X2 value Significance
NTD vs. control .325 NS
T vs. control .103 NS
L vs. control .295 NS
S vs. control .137 NS
0 vs. control .014 NS
E vs. control .789 NS
I vs. L .189 NS
I vs. S .202 NS
T vs. 0 0 NS
T vs. E .858 NS
L vs. S .005 NS
L vs. 0 .094 NS
L vs. E .528 NS
S vs. 0 .124 NS
S vs. E .041 NS
0 vs. E .720 NS

 

89

 

 

mo om H o o mHonuaoo

m o N o o m

HN HN o o o o

mN HN H H N m

N«H HMH o N o H

on «m o o N H
"mo mnHm

N « m o o m

mH NH N o H 0

MN NH 0 H « m

NOH «N m « HN H

Hm wH m H m H

z mmocHHH mo NuoumHn oz ceoaxas mEHH mIm mnuaoz NIH mnuooz macaw

 

 

mz¢mm mZHH 039 mom mmmZHHH MHHmmmm mo NMOHmHm

Hm mHm<H

90

TABLE 52

ANALYSIS OF INCIDENCE OF FEBRILE ILLNESS
DURING FIRST TWO MONTHS OF PREGNANCY

 

 

 

Comparison X2 value Significance

NTD vs. control 13.961 p< .001
T vs. control 27.283 p< .001
L vs. control 13.965 p< .001
S vs. control 7.902 p< .01
0 vs. control .497 NS
E vs. control .020 NS

T vs L 1.308 NS

T vs. S .979 NS

T vs 0 1.803 NS

T vs. E 1.298 NS

L vs S .006 NS

L vs. 0 .723 NS

L vs E .667 NS

S vs 0 .216 NS

S vs. E .302 NS

0 vs. E .524 NS

I vs. sibs 6.673 p< .01

L vs. sibs 30.143 p< .001

S vs. sibs .298 NS

0 vs. sibs .053 NS

E vs. sibs 0 NS

 

91

through ninth months was examined, no significant differences
emerged for any of the possible comparisons with X2 being
less than one for all comparisons (see Table 53). This im—
plies that history of febrile illness during the first two

months may be significant for T, L, and S level NTD.

ORAL CONTRACEPTIVES

Mothers of probands were questioned regarding oral con-
traceptive usage within three months of conception or during
pregnancy. The only significant differences were between
sibs and probands in the L group. The X2 value was 6.607,
with the corresponding significance level being .01. If
oral contraceptives are significant in the etiology of cer-
tain NTD, then the effect must be small since none of the
other comparisons were significant. Tables 54 and 55 sum—

marize the data and analyses.

ANTI-EMETICS

Analysis of anti-emetic usage yielded interesting re-
sults. Whereas the NTD vs. control comparison was not sig-
nificant, the T vs. control comparison was significant, with
a X2 of 4.04 and a significance level of .05. On the other
had, the L vs. sib comparison was the only significant com-
parison among those between probands and sibs. An additional
comparison was made between T sibs and L sibs, and although
more sibs in the T group were exposed to anti—emetics, the

difference was not significant. This then means

92

TABLE 53

ANALYSIS OF INCIDENCE OF FEBRILE ILLNESS HISTORY
DURING THE THIRD THROUGH NINTH MONTHS OF PREGNANCY

 

 

 

Comparison X2 value Significance
NTD vs. control 2.742 NS
I vs. control .458 NS
L vs. control .965 NS
S vs. control . .110 NS
0 vs. control .497 NS
E vs. control .020 NS
T vs L .016 NS
T vs. S .047 NS
I vs. 0 .494 NS
T vs. E .232 NS
L vs. S .021 NS
L vs. 0 .439 NS
L vs. E .312 NS
S vs. 0 .699 NS
S vs. E .314 NS
0 vs. E 0 NS
I vs. sibs .006 NS
L vs. sibs .708 NS
S vs. sibs .044 NS
0 vs. sibs 0 NS
E vs. sibs 0 NS

 

 

93

NO on N mHonuaoo

 

OH o H m
ON OH H o
mN ON m m
O«H HMH mH H
om mm H H
”No mnHm
N O H m
mH NH N O
«N ON « m
«OH HO mN H
Hm mN O H
z NuoumH: 0>Humwmz NuoumHn o>HuHmom osouo

 

 

ZOHHmmozou UZHMDD mo mo mmHzoS mmmmH szHHB mw<mD m>HHmmu<MBzoo H<mo

«m MHH<H

94

TABLE 55

ANALYSIS OF ORAL CONTRACEPTIVE USAGE
WITHIN THREE MONTHS OF CONCEPTION

 

 

 

Comparison X2 value Significance
NTD vs. control 2.481 NS
I vs. control .594 NS
L vs. control 3.224 NS
S vs. control .113 NS
0 vs. control .076 NS
E vs. control .063 NS
T vs. L .108 NS
T vs. S .028 NS
T vs 0 .105 NS
T vs. E .097 NS
L vs. S .347 NS
L vs. 0 .195 NS
L vs. E 0 NS
S vs 0 .079 NS
S vs. E .023 NS
0 vs. E .004 NS
T vs. sibs 3.280 NS
L vs. sibs 6.607 [)<.02
S vs. sibs .122 NS
0 vs. sibs .068 NS
E vs. sibs .117 NS

 

95

that apparently more mothers of T probands used anti-emetics
during all pregnancies, whereas L mothers tended to use
anti—emetics more often during the pregnancies which re—
sulted in affected offspring. See Tables 56 and 57 for data

and analyses.

HORMONES

Whereas the NTD vs. control comparison was not signifi-
cant, two significant differences emerged when hormone usage
during pregnancy was analyzed for each level. Mothers of 0
group probands reported using hormonal preparations more
often during pregnancy than did mothers of the L or control

groups. No other comparisons were significant (see Tables

58 and 59).

GYNECOLOGICAL PROBLEMS

No significant differences emerged for either NTD vs.
control, inter—group or intra—group comparisons when mothers
were evaluated for history of hormone influenced gynecolog—
ical problems. Tables 60 and 61 summarize the data and

analyses.

INTER-PREGNANCY GAP (IPG)

The NTD vs. control comparison was not significant.
However, when levels were examined separately, the L vs. 0,
L vs. E, S vs. 0, and S vs. E comparisons were significant.
Probands of the O and E groups were conceived within three

months of a preceding pregnancy more often than L or S

96

 

 

mo Hm NH mHouuooo
o N N m
NN ON N 0
ON NN H m
mmH mNH OH H
NO ON o H
“No mnHm
N m « m
OH O O o
NN OH « O
OOH ON ON H
HO OH NH 9
z NHOOMHH 0>HumOmz NuoumHn 0>HuHmom macho

 

 

wuz<zwmmm UZHMDQ mu<mb UHHMZmIHHZ< mo WMOHOHS

Om MHH<H

97

TABLE 57

ANALYSIS OF ANTI-EMETIC USAGE DURING PREGNANCY

 

 

 

Comparison X2 value Significance
NTD vs. control 1.755 NS
T vs. control 4.225 p( .05
L vs. control 1.185 NS
S vs. control .008 NS
0 vs. control 1.932 NS
E vs. control 3.249 NS
T vs L 1.754 NS
T vs S 2.571 NS
I vs. 0 .007 NS
T vs. E .302 NS
L vs. S .659 NS
L vs. 0 .622 NS
L vs. E 1.729 NS
S vs. 0 1.188 NS
S vs E 2.321 NS
0 vs. E .568 NS
I vs. sibs 1.635 NS
L vs. sibs 16.775 p< .001
S vs. sibs 1.003 NS
0 vs. sibs 3.370 NS
E vs. sibs .114 NS

 

98

 

 

mo OO O mHouudoo

o o O m

HN OH N 0

ON ON o m

««H mmH m H

OO «O N H
"mo mnHm

N m N O

OH OH O O

«N NN N O

OOH OO O H

Hm ON m H

z Nuouan m>HumOoz NuoumHn o>HuHmom asouo

 

 

woz<zwmmm UZHMDQ mu<mD mzozmom mo WMOHmHm

Om MHm<H

99

TABLE 59

ANALYSIS OF HORMONE USAGE DURING PREGNANCY

 

 

 

Comparison X2 value Significance
NTD vs. control 2.115 NS
T vs. control .218 NS
L vs. control .150 NS
S vs. control .016 NS
0 vs. control 7.868 p< .01
E vs. control 2.393 NS
T vs. L 0 NS
T vs. S .030 NS
T vs 0 2.461 NS
I vs. E .513 NS
L vs S .017 NS
L vs. 0 6.622 p< .02
L vs. E 1.428 NS
S vs. 0 2.428 NS
S vs. E .015 NS
0 vs. E .051 NS
T vs. sibs .030 NS
L vs. sibs 1.907 NS
S vs. sibs .565 NS
0 vs. sibs 2.018 NS
E vs. sibs .907 NS

 

100

 

 

NO OO O mHouusoo
N m N O
OH NH O o
NN OH O O
OO Hm N H
Hm on H H
z NuoumHn 0>Humwmz NuoumHn w>HuHmom aaouo

 

 

OEMHmomm H<UHUOHOUmsz QMH<HHMIMZOEMO$ mo MMOHmHm

Om MHH<H

l

TAB

01

LE 61

ANALYSIS OF MATERNAL HISTORY OF GYNECOLOGICAL PROBLEMS

 

 

 

Comparison X2 value Significance
NTD vs. control 1.320 NS
T vs control .124 NS
L vs control .076 NS
S vs. control .844 NS
0 vs. control 2.105 NS
E vs. control 3.565 N3
T vs. L .752 NS
T vs S .786 NS
I vs. 0 1.783 NS
T vs. E 2.279 NS
L vs. S .324 NS
L vs. 0 1.311 NS
L vs. E 1.582 NS
S vs. 0 .004 NS
S vs E .113 NS
0 vs. E .119 NS

 

102

probands. In addition, 0 probands were conceived within 7
months more often when compared to their normal sibs. This
implies that a short IPG (less than three months) may be
etiologically related to certain types of NTD (see Tables 62

and 63).

CONCEPTION AFTER ABORTION

The NTD vs. control comparison was not significant; how-
ever, the L vs. 0, S vs. 0, and 0 vs. control comparisons
were significant. There were more probands of the 0 group
conceived following an abortion. See Tables 64 and 65 for
data and analyses summaries.

In all comparisons, no significant differences were
found between the L and S groups or between the O and E
groups. This implies that there was no heterogeneity which
could be detected between those two pairs of groups, so that
they could be pooled for the purpose of analysis. Compari-
sons were then repeated pooling lumbar and sacral groups (LS),
and the other and encephalocele groups (OE). As before, no 4
significant differences were observed for seasonal variation,
ethnic origin, sex ratio, parity effect, NTD family history,
Rh blood type distribution, or ABO and Rh incompatibility
(see Table 66). However, differences were found among the
groups for the other variables, and these will be discussed

separately.

103

 

 

mm ON « m o H mHouucoo

« HH O H O H O

O «« o H o N o

«H OH o o O o m

Om H« « H o H H

NH OH o H o o H

macho
z +O « m N H "OOHoochmua cooeumn mcucoa No Honeaz

 

 

mmhzoz zH m<0 woz<zommmImMHzH

NO MHO<H

104

mwcHsch ucmOHchmHm
an

 

 

OO. OO. OO. NN.N mo.H NOO.H OHO. OHO. nHm .m> m
NN.N «Om¢.« ON.N ON.N ON.N qu. OO.H OO.H nHm .m> O
«0. Now. Now. OO.H ON. OOO. ON. 0 nHm .m> O
OO. mN. NN.H ON. OO. Non. NH. HHO. nHm .m> H
NN.N OH.N OH.N o o ONO. NOH. ONO. nHm .m> H
N.N N.N OH. OH. O HNH. o O m .m> O
HO. oo.m OO.m Om.m om. «HON.« «O. «O. m .m> m
OO.H OO.H oo.m Om.m Om.m *NmO.m OO.H mm.H o .m> m
O¢.N mq.N NH.N Nm.N ON. uNOHN.O OO. OO. O .m> H
mm.H mm.H OH. mm.N mm.N «HO0.0 om.m Om.m O .m> H
o OH. OH. om. om. COM. 0 O m .m> H
o.m o.m o.m o.m mNm. MOH.N NO.H NO.H m .m> H
ONO. mN. mN. ON. ON. «ON.N ON.H ON.H O .m> H
o o O o O «CO. 0 o m .m> H
mo.H NO.H ON. mO. mO. «CO. 0 O H .m> H
Hq.N N¢.N Nq.N O«.N ON. NOO.N NO. NO. HOHucou .m> m
OH. OH. NN. OH. OH. Omo.N m.N m.N Houucoo .m> 0
ON. ON. ON. om.H om.H ONO. o o Houucoo .m> m
ON. GO. OO.H NH.H NH.H NH«.H O O Houudoo .m> H
ON.N qm.N cm.N ON.H ON.H OOO. O O Houucoo .m> H
.moe Ow .moa NH .moe ON .moe OH .moe «W .moa mfl .woa Nw .moe HW :omHHmoeoo

 

 

mHzmzmmozH VHmHZOZ Wm m<w woz<zommmlmmHzH mo OHONH<Z<

OO MHO<H

105

 

 

OO «O O Houuaou
HH O N m
ON ON O 0
ON NN H O
m«H OOH OH H
OO «O « H
”O0 mOHO
N « m O
OH O N O
«N NN N O
OOH OO OH H
Hm MN m .H.
z LuHHOm>HH nouwm aoHuomocoo GOHuuonm Hmumm nOHuamoaou osouo

 

 

OUZHHOHO Qz< ODZ<Oomm UZOZ< OZOHHMOO< MOHm< OszmDooo OZOHHHMUZOU mo ZOHHmomomm

«O OHO<H

 

 

106

TABLE 65

ANALYSIS OF DISTRIBUTION OF CONCEPTION
OCCURRING AFTER ABORTION

 

 

 

Comparison X2 value Significance
NTD vs. control .777 NS
I vs. control 1.752 NS
L vs. control 0 2 NS
S vs. control .149 NS
0 vs. control 5.937 p< .02
E vs. control 1.889 NS
T vs. L 2.260 NS
I vs. S 1.726 NS
T vs. 0 1.166 NS
I vs. E .226 NS
L vs. S .297 NS
L vs. 0 7.115 p< .01
L vs. E 2.136 NS
S vs. 0 5.632 p< .02
S vs. E 2.564 NS
0 vs. E .028 NS
T vs. sibs 2.775 NS
L vs. sibs .896 NS
S vs. sibs .312 NS
0 vs. sibs 1.192 NS
E vs. sibs .528 NS

 

107

NHHmcommmm OmumOEoo

ism

Houucoo«

 

 

I I aHo. OHN.H No«.H NNO. «mN.H HOHHHO
IHumaaoocH Om<

I I Noo. ONH. mac. HHo. Hmo. Hmcnmuta
I mmNu OooHH Hm

I I NNO. NNO. O O«O. OOO.N Hmcumume
I OONO OOOHO Hm

I I OOH. ONO. ««O. ONO.H moo. uoommm
NuHumOmaHum

OOH. OHO. NOO. NOH. NOO. OOO. ONN. uommmm
NuHOH>muOmaHum
O«O. H«O.H OO«. HNo. H«O.H OHO. HHO. OHumu xOO
««OO.H C.3..O«H.H OO0.0 ON0.0H OHN.OH O«0.0 ON0.0H Hmcomwmm

mOHm .> mo mOHm .> OH mo .> OH mo .> H OH .> H O .> mo 0 .> OH mHanum>

um

 

 

OMDH¢> x

<H<Q OOHoom UZHOD OZOOHM<OZOU Hz<uHmHonOIzoz

OO mHO<H

108

ouuco
H 0*

 

 

I OOO.H OOO.H ««N.N «OO. NOO. Hmaumuma
CHOHuo UHGHum
I O«O. NHO. OOO.H .HOO. OO«. Hmaumuma
cHOHuo OHozum
I O HNo. OON. OHO. HOO. NuHHHO
IHumOEoocH HO
OOHO .> mo OOHO .> OH mo .> OH mo .> H OH .> H O .> mo 0 .> OH OHOmHum>

 

 

He.ua60O OO mHm<H

109

ABORTIONS IN SIBSHIPS

Pooled comparisons showed that OE vs. control, T vs. LS,
and LS vs. OE comparisons were significant. The T and OE
groups each had an elevated rate of abortions. See Table 67

for analyses.

FAMILY HISTORY OF BIRTH DEFECTS

When the data were pooled, the only significant differ-
ence in the incidence of birth defects was that fewer rela—
tives of LS probands were affected with pyloric stenosis

than expected. The X2 value was 9.893 (p< .01).

BLOOD TYPES - ABC

The blood type distribution was significantly different
in that more mothers and fathers of LS group probands were
blood type B and fewer were blood type A when compared to
expected population values. Mothers of OE probands were
significantly more of ten blood type AB when compared to

controls. Tables 68-77 summarize the findings.

ILLNESS

Pooled data comparisons showed that the LS vs. sib and
the LS vs. control comparisons were significant in that
mothers of LS proBands reportedly had more febrile illness
during the first two months of pregnancy. In addition, the
T vs. OE comparison was significant, with T probands'

mothers reporting more instances of febrile illness during

110

 

 

Hoo. Va 393 we .m> OH

Oz OOO.H mo .m> H

NO. vo ON0.0 OH .m> H

:5. va HNO.oH H6350 .65 mo

Oz HHN. Houuaoo .m> OH
ooemonHaOHO maHm> Nx somHumoBoo

 

 

OmHmOmHO ZH MUZMQHUZH ZOHHMOO< mom <H<Q QMHoom mo OHOMH<Z<

NO OHO<H

111

TABLE 68

ANALYSIS OF MATERNAL BLOOD TYPES

POOLED DATA

 

 

Comparison X2

 

 

value Significance
control 23.631 p<..001
control 7.941 p< .05
LS 4.082 NS
OE .765 NS
OE 4.199 NS
TABLE 69

ANALYSIS OF PATERNAL BLOOD TYPES

POOLED DATA

 

 

 

Comparison X value Significance
control 17.102 p< .001
control 5.828 NS

LS .171 NS
OE .826 NS
OE .760 NS

 

112

TABLE 70

ANALYSIS OF BLOOD TYPE A DISTRIBUTION - MATERNAL

 

 

 

 

Comparison X2 value Significance
LS vs. control 8.156 'p< .01
OE vs. control .163 NS
T vs. LS 3.348 NS
T vs. OE .229 NS
LS vs. OE 1.256 NS
TABLE 71

ANALYSIS OF BLOOD TYPE A DISTRIBUTION - PATERNAL

 

 

 

Comparison X2 value Significance
LS vs. control 6.573 p( .01
OE vs. control .608 NS
T vs. LS .002 NS
T vs. OE .056 NS

LS vs. GB .113 NS

 

113

TABLE 72

ANALSYSIS OF BLOOD TYPE B DISTRIBUTION - MATERNAL

 

 

X2 value

 

 

Comparison Significance
LS vs. control 15.741 p< .001
OE vs. control .361 NS
T vs. LS 1.042 NS
T vs. OE .229 NS
OE vs. LS .055 NS
TABLE 73

ANALYSIS OF BLOOD TYPE B DISTRIBUTION - PATERNAL

 

 

X2 value

 

Comparison Significance
LS vs. control 11.290 p< .001

OE vs. control 1.890 NS

T vs. LS .028 NS

T vs. OE .022 NS

LS vs. OE .006 NS

 

114

TABLE 74

 

 

 

 

 

 

 

ANALYSIS OF BLOOD TYPE 0 DISTRIBUTION - MATERNAL
2
Comparison X value Significance
LS vs. control .024 NS
OE vs. control .004 NS
T vs. LS 0 NS
T vs. OE .580 NS
LS vs. OE .109 NS
TABLE 75
ANALYSIS OF BLOOD TYPE 0 DISTRIBUTION - PATERNAL
Comparison X2 value Significance
LS vs. control .001 NS
OE Vs. control .466 NS
T vs. LS .086 NS
T vs. OE .538 NS
LS vs. OE .416 NS

 

115

TABLE 76

ANALYSIS OF BLOOD TYPE AB DISTRIBUTION - MATERNAL

 

 

2

 

 

Comparison X value Significance
LS vs. control 3.321 NS
OE vs. control 4.664 p< .05
T vs. LS 0 NS
I vs. OE 0 NS
LS vs. OE .852 NS
TABLE 77

ANALYSIS OF BLOOD TYPE AB DISTRIBUTION - PATERNAL

 

 

 

Comparison X2 value Significance
LS vs. control 2.262 NS
OE vs. control .759 N3
T vs. LS .067 NS
T vs. OE .010 NS

LS vs. OE .475 NS

 

116

the first two months. See Table 78.

ORAL CONTRACEPTIVES

Pooled data analysis revealed that more mothers of LS
probands reported oral contraceptive usage within three
months of conception when compared to normal sibs. No

other comparisons were significant (Table 79).

ANTI-EMETICS

Whereas only the L vs. sib and I vs. control compari-
sons were significant when each group was examined sepa-
rately; when the groups were combined, not only was the LS
vs. sib comparison significant, but the LS vs. OE and OE vs.
control comparisons were significant as well. An additional
comparison was made between siblings of each group and it
was noted that LS mothers significantly less often took
anti-emetics during normal pregnancies than did T or OE

mothers. Table 80 summarizes the analyses.

HORMONES
The L8 vs. OE and OE vs. control comparisons were sig-
nificant. In addition, the OE vs. sib comparison was sig-

nificant. The results of analyses are summarized in Table

81.

GYNECOLOGICAL PROBLEMS
When pooled data was used, the OE vs. control compari-

son was significant, in that more mothers of OE probands

117

TABLE 78

ANALYSIS OF POOLED DATA FOR FEBRILE ILLNESS

 

 

X2 value

 

Comparison Significance
LS vs. control 13.793 p< .001

OE vs. control .306 NS

T vs. LS 1.496 NS

I vs. OE 9.666 p< .01

LS vs. OE 1.887 NS

LS vs. sibs 28.505 p< .001

OE vs. sibs .025 NS

 

ANALYSIS OF POOLED

118

TABLE 79

DATA FOR ORAL CONTRACEPTIVE USAGE

 

 

 

Comparison X2 value Significance
LS vs. control 2.877 NS
OE vs. control .100 NS
I vs. LS .046 NS
T vs. OE .031 NS
LS vs. OE .270 NS
LS vs. sibs 6.178 p< .02
OE vs. sibs .166 NS

 

119

 

mz
no. on

mo. Va

Oz

Ho. Va

mo. Oh
mz

OZ

mo. vO

Oz

NOH.

NON.O

HNN.«

OOO.H

HON.O

NO0.0
H«N.

OOH.O

ONO.m

««O.

mOHm mo .m> hOHm H

BOHm mo .m> mnHm mH

mOHm OH .m> mnHm a

hOHm .h> mo

mnHm .m> mH

mo .m> OH
mo .m> H

OH .m> H

Houucoo .m> mo

Houuaoo .m> OH

 

mucmonHcOHO

msHm> Nx

comHumOEoo

 

 

Woz<zummm UZHODQ m0<mD OHHMZMIHHZ< mom <H<Q QMHoom mo OHOMH<Z<

0O WHO<H

TABLE 81

ANALYSIS OF POOLED DATA FOR HORMONAL USAGE DURING PREGNANCY

 

 

 

Comparison X2 value Significance
LS vs. control .284 1 NS
OE vs. control 9.627 p< .01
I vs. LS .133 NS
I vs. 0E 2.801 NS
LS vs. OE 8.727 p< .01
LS vs. sibs .648 NS

OE vs. sibs 4.212 p< .05

 

121

had hormonal types of gynecological problems than did con-

trols. See Table 82.

IPG

Additional differences emerged for analysis of this
variable. Whereas only the I vs. 0, T vs. E, and S vs. 0
comparisons were significant when groups were examined sepa-
rately, combining the groups yielded significant differences
for T vs. OE, LS vs. OE, OE vs. sibs, and OE vs. control
comparisons. In each case, probands of the OE group had
shorter IPG's than did probands of the T or LS groups, con-

trols, or sibs. See Table 83.

CONCEPTION AFTER ABORTION
The LS vs. OE, OE vs. control, and OE vs. sib compari—
sons were significant, as more OE probands were conceived

after an abortion. The analyses are given in Table 84.

In summary, it was shown that heterogeneity exists between
NTD when separated by location of defect. Lumbar and sacral
defects appeared to be one homogeneous group, whereas en-
cephalocele and other level defects appeared to be a second
homogeneous group. This was done by Xzanalysis of contin-
gency tables and demonstrating that dependence on classifi-

cation exists.

122

 

 

Oz OOO.N mo .w> OH
Oz ONH.O mo .m> H
Oz O«O. OH .m> H
m0. VG «mm.q HOHUSOU .w> m0
Oz O««. Houucoo .m> OH
mocmunHsOHO osHm> x somHquEOO

N

 

 

NO MHO<H

OZmHmomm HOUHUOHOUOZVO mo WOOHOHS mom <H<H QmHoom mo OHO>H<Z<

123

 

 

Hoo. Va H«0.0H mo .O> OH

Oz mom.O mo .m> H

Oz OON. OH .m> 9

mo. va OON.« HouucOo .m> mo

Oz OOH.H Houucoo .m> OH
mo:m0HOH:OHO msHm> Nx comHumaeoo

 

 

<H<Q DMHOOA

OmHzoz mmmmfi OH H<DOm mo z<mH OOmH mo OmH mo OHOwH<z<

OO OHOOH

124

 

 

HO. OH HON.O hth .m> mo
Oz HNO.N OOHO .m> OH
Hoo. Va ONO.HH Ho .m> OH
Oz «HN.N mo .m> H
Oz H«H.N OH .m> H
Ho. va H«O.H Houstoo .m> O0
O2 O«H. Houucoo .m> OH
mocOOHOHcOHO msHm> N aomHumOEou

N

 

 

ZOHHMOO< z< MOHm< UZHMMDUUO
OZOHHOMUZOU mo ZOHHDOHMHOHQ mom <H<H anoom mo OHOWH<Z¢

«O OHO<H

DISCUSSION

SEASONAL VARIATION

Most authors have noted seasonal variation in NTD inci-
dences. A few studies have shown that the seasonal patterns
change from year to year, and others have shown that not all
NTD show the same pattern or variation. In the present
study, no significant variation was found when the NTD group
was compared to controls, although there appeared to be a
higher incidence in the last half of the year as compared to
the first half of the year. When the NTD group was examined
by defect location, no significant differences emerged.
There are four possible reasons for the failure to detect a
seasonal effect. One, the numbers of probands were too
small to detect an effect; second, a seasonal pattern which
Shifts from year to year would not be detected; third, a
local seasonal effect may be undetected because of the in-
clusion of national data; fourth, no seasonal effect exists.
It is not possible to discern between the different possi-

bilities.

SEX RATIO
No significant differences between sex ratios in any
0f the groups were found, although numberically there were

feWer males than females in three of the five groups. Other

125

126

studies cited had found fewer males than females affected
with NTD, with the percentage of males ranging between 39%
and 47% for spina bifida, and 25% and 44% for anencephaly.
In almost all studies, the percentage of male probands was
less in the anencephaly group than in the spina bifida group.
In the present study, the percentage of male probands in the
NTD group was 45.7%, which is within the range cited. How-
ever, neither the lumbar group nor the encephalocele group
had an excess of affected females. The equal sex distribu-
tion in the encephalocele group is supported by Czeizel's
finding of a sex ratio of 49%. The equal sex ratio in the
lumbar group can be explained by the observation of Night-

127 that whereas more spina bifida affected fe-

ingale gt gt.
males are born, the mortality is higher in females. Since
this study's population was obtained mostly from spina bi-

fida parents' groups, it is not surprising that the sex ratio

was equal, since almost all of the probands were still alive.

PARITY
The present study did not find a significantly greater
incidence of first-born probands. This finding is not in

accordance with the findings of Carter gt gt.28, William—

son31, and Czeizel gt gt.33, who each noted a greater in-
cidence of probands which were first liveborn. The most
likely explanation is that the numbers in the present study

were too small to detect a significant parity effect, since

the percentage of probands which were the first-born was

127

greater than the control percentage in all instances.

The earlier studies used, as control data, population
figures of first-born incidence. Since families of NTD af—
fected individuals are known to differ epidemiologically from
other families (i.e., greater abortion incidence, lower
social class, different ethnic origin, etc.), a more valid
method would be to derive the proportion of first-horns and
first pregnancies from the NTD families themselves, and then
determine if the probands follow the same distribution pat-
tern. When Williamson's, Carter's and Czeizel's data are
analyzed in this manner, it is found that in Williamson's
and Carter's studies, there were fewer first-borne in the
index families than in the control group; in Czeizel's data,
there were fewer first-horns in the anencephaly and encepha-
locele families but more in the spina bifida families. As a
result, the only alterations in the findings were that SBC's
were significantly more often first-born whereas anencepha-
lics were not in Williamson's study. In the present study,
there were more first-borns in the index families than in
the control group, so the seeming excess of first-borne in
the index group as compared to the control group disappears.

When the data in the present study were examined re-
garding pregnancy order, the probands were not significantly
more often the first pregnancy. Carter's and Williamson's
data could be examined for this aspect, and it was found

that their data showed that the proband was not significantly

128

more often the first pregnancy (see Table 85).

It becomes apparent that it is not the first pregnancy
which increases the risk, but rather the first—born. The
inference is that the abortion rate must be higher among the
early pregnancies. If one accepts the findings of Record gt
a1.76

, who found that the risk of NTD goes up with increasing
livebirths, then the postulate that these aborted fetuses are
also affected with NTD is valid, i.e., subsequently born sibs
would be expected to have a higher risk of themselves being
affected with a NTD.

There is still no explanation why the liveborn and
aborted fetuses occur earlier in the pregnancy order rather
than randomly. It is clear that a parity effect exists in
some populations, what the basis is for this effect is ob-

scure o

ETHNIC ORIGIN

The role of ethnic origin was examined by comparing the
incidence of Anglo-Saxon ancestry among mothers and fathers
of probands. Although it has been reported that migrants
from regions of high incidence have a higher risk than per-
sons in the same area who are from regions of low incidence,
it has been shown that the time of immigration is important,
and determines the rate based on ethnic origin. Since that
information was not elicited by this study, a meaningful

analysis could not be made. Although the T group had more

129

Ho. Va

 

 

.31.
80. Va
N«
no. Va
3.
OOO.N HHO. OH.N« O.N« m :
«ON NH.N «ONN.HO OO.HO O.N« HO :
«NN«N.ON ««O0.0« HO.«« m.H« < I HONHONO
OOH. OOH. O0.00 HN.H« umunmo
O«OO.«« «HN.« «O.«O OO.HO OO =
«O.H HO.N OO.NO OO.NO < I HHomamHHHHS
mmHHHamm mecH .> mHouucoo .> mmHHHEmm xovoH mHouucoo NODuO

”moaMOHHHcOHO

uoH mouoOIuOuHH Ho moomOHocH

 

OZMOOIHOMHM mo moZmnHozH OOHummxm

mo ZOHH<ZHmeHmn mom OMHHHZ<N NmQZH QZHOD Hommmm NHHM<H<SHmm

mO MHO<H

130

parents of Anglo-Saxon origin, that incidence was not signi-

ficant.

FAMILY HISTORY OF NTD

Overall, the incidence of NTD in family members was
3.2% of sibs, .5% of second degree, and .1% of third degree
relatives being affected. Previous studies had found inci-
dences among siblings of spina bifida probands being between
2.6% and 6.1%. In U.S. studies, Cowchock gt gt.66 found
that the incidence of NTD among siblings of probands with
spina bifida was 2.5%. Janerich noted a recurrence risk of
1.8%. Neither figure is significantly different from the
present study (szalues = .43 and 2.00 respectively).

In the studies in which encephaloceles were examined

separately, incidences were 0%33, 5.6%43, and 6.0%22.

Holmes gt gt.128 made the point that inclusion of Meckel's
Syndrome will artificially increase the recurrence risk,
since Meckel's Syndrome is an autosomal recessive disorder

and has a recurrence risk of 25%. Neither Lorber gt gt.22

nor Carter gt gt.43 make any mention of any consideration
being given to ruling out Meckel's Syndrome in their data
collection. Since Holmes gtgt.128 found that 4.7% of all
NTD (in the U.S.) are caused by Meckel's Syndrome, and en-
cephaloceles are 10% of all NTD ( in the U.S.), then the
inference can be made that 21% of encephaloceles are due to

Meckel's Syndrome (provided that Meckel's Syndrome always

has an encephalocele as opposed to some other NTD). If this

131

were the case, then the recurrence risk among sibs of en—
cephalocele affected individuals (without making the dis—
tinction between Meckel's and "multifactorial" cases) would
be 5.3%, if the "multifactorial" cases had a 0% recurrence
risk. The risk would change based on the actual proportion
of Meckel's cases which have an encephalocele and the risk
to the sibs of the "multifactorial" cases.

Among second degree relatives, the incidences in the
literature ranged from .2 - .5%, with a pooled value of .4%.
In the present study, the incidence among second degree rel—
atives was .5%, not significantly different from the pooled
value (X2 = .061). Among third degree relatives, reported
incidences ranged from 0% to .7%, with a pooled value of
.5%. The present study found an incidence of .1% for third
degree relatives, which is significantly less than the pooled
value (X2 = 10.358, p< .002). The reason for this difference
is that the published incidences are almost exclusively from
Great Britain, where a higher risk of NTD exists among the
relatives.

In addition to the actual numerical risk figures, it is
important to note that in the present study, affected sib-
lings of lumbo-sacral affected individuals also had lesions
of the lumbo-sacral area, whereas affected siblings of T and
OE affected individuals had anencephaly. Although previous
studies had found that siblings of affected individuals were

almost as likely to have anencephaly as spina bifida,

132
Cowchock gt gt.66 illustrated that the defect in affected
siblings is usually the same as that in the proband. This
implies that either siblings of more severely affected in—
dividuals tend to be more severely affected themselVes, in
keeping with the multifactorial model; or that heterogeneity
exists among the NTD and families are prone to only one

type of NTD, possibly on an embryological basis.

FAMILY HISTORY OF ABORTION
Some studies have noted a slight increase in the inci-

dence of abortions in sibships (McDonald81, Record gt gt.76)’

while others (Carter28, Richards67, Williamson31, and

Lippman-Hand gt_gt.38) have not. Overall, the incidence of
abortions in the NTD group was 25.4% as compared to 20.51%
in the controls; when probands are also considered, then the
percentage of pregnancies aborted was 16.4% among the index
group and 13.1% among the controls. However, the T and OE,
but not the LS groups accounted for the increased incidence
of abortions, with that increased incidence being signifi-
cant. These data are difficult to compare to previous
studies, since either control data were not given, or the
general population abortion incidence Of 15% was given for
comparison. When the percentage of siblings which were abor-
ted was calculated, the derived figure was not a representa-
tion of the mother's reproductive history since the proband,

which was always a term pregnancy, was not included in the

calculation. Therefore, the number of term pregnancies were

133

not taken into account when deriving the abortion incidence.
When probands were included in the calculated incidence of
abortion, this could not be compared, since the population
figure includes couples all of whose pregnancies have abor-
ted, whereas the index group is biased because the mother
has had at least one term pregnancy.

In the two studies which did obtain comparable data, it
was shown that the incidence of abortion among siblings is
3.5 - 4.2% greater when the index patient has a NTD. In the
present study, the incidence of abortion in the NTD group
was 4.8% greater than in the controls (not significant) and
was attributable solely to families of probands of T, O and
E type defects (individually significant). The difference
in the present study is based on the larger contribution
from families with T, E and 0 level defects. Since other
studies had pooled all NTD, it can be speculated that whether
or not abortion incidence is significant in that study de-
pends on the proportion of the total sample made up of the
subgroups with high abortion rates. This study clearly de-
monstrates that the overall small increase in abortion rates
is attributable to small subgroups of NTD.

Although it is apparent that the abortion incidence is
higher in OE and T sibships than in LS sibships, it cannot
be discerned whether the basis for the excess is the same in
the two groups. Since a suggestion had been made that ex-

cess abortions in sibships are similarly affected fetuses,

134

and that affected males may be more likely to miscarry than
affected females, the paucity of males and excess of abor-
tions in T sibships may be due to affected males being mis-
carried. Since OE sibships had an almost equal sex distri-
bution among probands and sibs, it is likely that the basis

for the excess abortions in these sibships is different.

FAMILY HISTORY OF OTHER DEFECTS

In the present study, none of the siblings of any pro-
band group were reported as having isolated hydrocephalus,
although previous studies have indicated that the incidence
of hydrocephalus is increased among siblings of NTD pro—
bands. However, the small number of siblings in each of the
present groups was the most likely explanation for this
lack. The expected number of affected siblings with hydro-
cephalus would be .54, given the observed incidence of .22%
among siblings of NTD affected individuals.

The incidence of other birth defects with a multifac-
torial cause has also been noted by other studies. Com—
bining the findings from prior studies, it was apparent that
oral clefting may be the most likely to be increased in the
siblings of NTD affected individuals. However, no increase
in clefts was noted among sibs of any of the groups, per-
haps due to the small sample size. The expected number of
affected siblings was 1.04, given the observed incidence of

.42% found by other studies.

135

Since the incidences of both hydrocephalus and
clefting, although significantly increased, are still small,
it would be pertinent to further characterize the families
with both NTD and the above-mentioned defects. It may be
possible that hydrocephalus is more likely to occur in sib-
lings of probands whose NTD is of a rupture type of defect,
which could be the smaller subgroup of NTD. Since clefting
and NTD have had similar environmental factors suggested as
being important (e.g., folate deficiency, hyperthermia,
hormone imbalance), it can be postulated that there exist
genes which confer susceptibility to a specific teratogen,
and that the type of defect depends on the timing of the in-
sult. In this case a genetic component could be concerned
with neural tube and lip and palate closure (both mid-line
closure processes). The only significant finding in the
present study was that fewer than expected relatives of LS
affected individuals had pyloric stenosis.

In previous studies as well, there was a small defi-
ciency of pyloric stenosis affected siblings, although the
difference was not significant. The reason for this is un—
known, and whether it is due to under-reporting by the
relatives, as opposed to a genuine negative relationship

between the two defects cannot be discerned at this point.

BLOOD TYPES

Since some studies had found higher incidences of blood
type 0 in mothers of anencephalics, and others had found
higher incidences of mothers having Rh- blood type, the data
from the present study were examined. Mothers and fathers of
the LS group were reportedly more often of blood type B and
less often of blood type A than expected. Although the
studies by Carter gtgtfl+3 and Czeizel gtgt.33 nOted no sig-
nificant differences in blood type distribution, when index
groups were compared to controls, both studies showed fewer
mothers of spina bifida affected individuals having blood

type A. When Carter's and Czeizel's data were put in the

form A vs. not A,the numbers were:

Carter A not A Czeizel A not A
observe 104 161 61 121
expect 110 155 76 106
2 2
X = .56, NS X = 5.08, p< .05

Since Carter included encephaloceles with the spina
bifida group, it is possible that his data may not be com-
parable.

Since the incidence of blood type A is the same in Great
Britain as it is in the U.S., a higher proportion of indivi-
duals in the index group would not account for the skewed
blood type distribution. Therefore the reason for this
finding is unclear, but since the deficiency exists in
Carter and Czeizel's data, further investigation is merited.

Baker and Sherry86 found the incidence of Rh- blood to

137

be higher in mothers having children with a NTD (n=28, signi-
ficant at the .02 level). Czeizel gt gt.33 found the inci-
dence of Rh- blood type in mothers of spina bifida probands
was 25%, whereas it was not significantly increased in mothers
of anencephalics or encephaloceles. Other authors have noted
an increased incidence of Rh- blood type in mothers of SBC
affected offspring. In the present study as well the inci-
dences of Rh- blood type in mothers were higher in all NTD
groups (21% for T, 22% for LS, and 19% for OE) although the
difference was not significant.

When the data from the present study were partitioned
by parity, it was found that the incidence of Rh- mothers
decreased with parity, although not significantly so. This
is in contradiction to the observation by Golding and But-

ler87

, who had proposed that Rh isoimmunization may be etio-
logically significant. The present study noted that the in-
cidence of Rh incompatibility among parents of index cases
was not increased over the incidence among controls. If Rh
antibodies were involved in causing NTD, then an excess of
Rh incompatibility should be observed. The incidence of Rh
incompatibility was lower than expected.

Secondly, if Rh isoimmunization were an important
factor, then a primaparity effect which was been found
reasonably consistently in other studies should not be

noted. It seems that the Rh- blood type may be related in

some other, more obscure fashion than by isoimmunization.

138

FEBRILE ILLNESS

Overall, 19.0% of index mothers reported having a fe-
brile illness during the first two months of pregnancy.
Previous studies examining the percentage of mothers having
febrile illness during pregnancy have not used the same cri-
teria. Miller gt gt.98 found that 11% of mothers of anen-
cephalics reported hyperthermic episodes at or near the time
of anterior neuropore closure. Chance gtgt.99 found that
3/43 (6.98%) of mothers having spina bifida affected infants
(level L-5 or higher) reported hyperthermic episodes at or
near the time of posterior neuropore closure. In a prospec-
tive study, Coffey gt gt.96 found that 74% of mothers having
children with NTD reported having influenza during pregnancy
(34% during the first trimester). The present data are still
not inconsistent with their findings. Although Kleine—
brecht gt gt.97 did not find a significant difference for
influenza or febrile illness during the first twelve weeks,
it is possible that their time frame was too large. Their
data showed that the incidence of NTD among mothers having
influenza was .9% and .7% among mothers having febrile ill-
mass as compared to .5% and .4% of controls. This finding
is not significantly different from Coffey's incidence of
1.2% of NTD among mothers having influenza (X2 = 1.21).

Whereas it is apparent that hyperthermia may be signi—

ficant in the etiology of some NTD, it appears that it is

onlgr important in causing LS and T type defects. Since LS

139

and T defects are consistent with neural tube non-closure,
it is possible that hyperthermia interferes with mid—line
closure rather than neural tube rupture. The finding that
hyperthermia in the tenth week of pregnancy is related to
clefting supports the hypothesis that hyperthermia affects

mid—line closure processes.

ORAL CONTRACEPTIVES

19.9% of index mothers reported oral contraceptive
usage within three months of conception as compared to 11.1%
of controls. When partitioned by level, it was found that
usage was reported by 19.4% of T mothers, 21.1% of LS mothers,
and 13.6% of OE mothers. Significantly more mothers of pro-
bands with LS defects reported using oral contraceptives
within three months of conception or during pregnancy as com-
pared to normal sibs. None of the other comparisons were
significant. This data supports the prospective findings of
Kasan gt gt.106 which showed that women who took oral con-
traceptives within three months of conception were more than
twice as likely to have a child with a NTD. It is especially
noteworthy that when the encephaloceles and iniencephalics
were considered separately, there was no significant differ-
ence in incidence of these defects, while the incidence of
anencephaly and spina bifida affected infants remained ele-
vated with a X2 value of 9.8. Together with the present
study, it suggests that oral contraceptive usage within

three months of conception may influence the risk of having

140

a child with a NTD of a certain type.

Since the usage of oral contraceptives at most triples
the risk of NTD, it is likely that oral contraceptives are
peripherally, but not directly, involved. The could possibly
alter the vitamin and mineral levels in susceptible indivi-

duals, which in turn would disrupt neural tube closure.

ANTI-EMETICS

Overall, 29.8% of mothers of NTD probands reported anti-
emetic ingestion during pregnancy. However, only mothers of
OE and T probands reported ingestion of anti-emetics more
often than did control mothers. Although mothers of the T
group also reported taking anti-emetics more often than did
mothers of the LS group, the difference was not significant.
Whereas the LS vs. sib comparison was significant, the T vs.
sib and OE vs. sib comparisons were not. Comparisons re-
vealed that mothers of OE and T groups took anti-emetics more
often during all pregnancies than did LS mothers.

The OE vs. LS proband comparison supports the findings
by Cordero gt 31.117, who had found that anti-emetic usage
was significant for encephaloceles, but not for other NTD.
However, the observation that OE and T mothers took anti—
emetics more often in all pregnancies makes the conclusion
tenuous. It is impossible to discern whether the cause of
hyperemesis, hormone fluctuation, or the result of hyper-
emesis, mineral imbalances, is significant. It is also dif-

ficult to discern whether the mechanism is the same for both

 

141

OE and T defects. However, it is possible to state that
since Cordero found that the incidence of encephaloceles was
only doubled, anti-emetics are unlikely to be teratogens
which directly affect neural tube formation, but rather are
peripherally involved by reflecting another process or pro-

cesses which are more closely related.

HORMONE USAGE

Significantly more mothers reported ingesting hormone
preparations during pregnancy than did LS or control mothers.
There is a paucity of research done on whether hormones play
a role in NTD etiology. The only studies encountered in the

literature were by Greenberg gt gt.103, who examined the hor-

monal pregnancy tests; and Ahlgren gt gt.125 who noted that
clomiphene may be a significant factor. Neither study
clearly indicated hormones as important causative factors
in NTD, although mothers of the index groups had a higher in-
cidence of usage as compared to controls in each study. The
present study suggests that hormones are significant only
for OE type defects.

Since OE type defects make up a small percentage of
all NTD, it is not surprising that other studies have not
identified definitive relationships between hormones and
NTD. It should be noted that since a strong relationship
was not found in the present study, it seems likely that

hormones in themselves are not teratogens, but rather re-

flect an underlying process such as hormonal imbalance.

142

GYNECOLOGICAL PROBLEMS

Overall, 9.3% of the index mothers reported gyneco-
logical problems as compared to 4.8% of controls. Only
mothers of the OE group significantly more often reported
gynecological problems, including infertility, anovulation,
highly irregular periods, or hypothyroidism. Ahlgren125
noted that women prone to having NTD children were subfer-
tile; while others believe that mothers of NTD affected
children are more fertile, based on their observation that
dizygous twinning rates and anencephaly rates are positively

39 reported that half of the mothers

correlated. Wynne-Davies
of spina bifida children reported gynecological problems, in-
cluding irregular periods, infertility, or other menstrual
disorders, as compared to less than one quarter of controls:.
Although the numbers are different in her study and the pre-
sent study, the proportions are the same. This implies

that mothers who have children with certain NTD are also

more likely to have gynecological problems that are hor-
monally caused. This is consistent with the previous hy—
pothesis regarding the use of anti-emetics and hormones and
OE type defects. This also implies that hormonal imbalances

may be significant in causing neural tube rupture, but not

neural tube non—closure.

IPG AND ABORTION PRECEDING CONCEPTION
A short IPG and occurrence of conception following an

abortion are significant factors in the OE group. These

143

support the fetus-interaction theory proposed by Knoxlls.
This theory states that NTD are the result of unfavorable
interaction between residual trophoblast from a miscarriage
and a subsequent pregnancy. Support for this theory comes
from the findings of Gardiner gt gt.129, who described an
increased incidence of malformations in pregnancies follow-
ing an abortion, as compared to pregnancies following viable
births. They also found that the IPG tended to be shorter
for the index cases, especially where the result of the
pregnancy was a NTD. However, the authors did not mention
if a specific type of NTD was noted.

Record gt gt.76 noted a shorter IPG preceding the birth
of a proband with a NTD as compared to controls (29.9% vs.
33.6%), although they did not comment on the significance.
When separated by type of NTD, they found that the shortest
mean IPG was for the spina bifida group (25.9), followed by
anencephalics (30.4) and hydrocephalics (37.3).

It was possible to examine the data of Williamson3l,
Carter gt gt.28, and Nevin gt gt.74 regarding the abortion
rate (see Table 86). When their data were pooled, 14.9%
of spina bifida probands followed an abortion as compared
to 9.8% of anencephalics, which was significant at the .05
level (X2 = 6.481). In the present study, 19.2% of all NTD
probands followed an abortion as compared to 14.3% of con-

trols. Only the OE group was significant in having a

shorter IPG or following an abortion when compared to the

 

144

TABLE 86

 

 

 

PROPORTION OF PREGNANCIES PRECEDED BY AN ABORTION
Reference Defect in proband: SB
yes no yes no
31 9 59 4 24
28 60 363 24 337
74 24 110 19 73
Total 93 532 47 434

 

 

145

other groups or controls. When the present data were com-
pared to the data of Williamson, Carter and Nevin, the T and
LS groups were not significantly different (X2 = 1.919 and
.243 respectively), whereas the OE comparison was signifi-
cant at the .001 level (X2 = 12.652). It is unfortunate that
the appendix in the Carter gt gt.43 study which listed en-
cephaloceles separately did not give information on miscar-
riages in the sibship.

The implication from these findings are that whereas
NTD individuals are more likely as a whole to follow an

abortion and to have a shorter IPG, that tendency is more

prominent in the OE group.

SUMMARY

The present study has attempted to show that differences
in either epidemiological or etiological factors exist when
NTD are divided according to level of the defect. In gen—
eral, the significant factors for the OE group were hormonal
or maternal in that siblings were aborted more frequently,
hormone ingestion was reported more often during pregnancy,
the mothers more often had hormonal gynecological problems,
the inter-pregnancy gap tended to be shorter, and the con-
ception of the affected individual occurred after an abor-
tion more often. For the LS and T groups, significant fac-
tors included febrile illness and oral contraceptive use
within three months of conception. The ABO blood type dis-
tribution was also significant in the LS group and the 0
group.

The significant differences which reflect heterogeneity
(intra-group comparisons) are as follows:

T vs. LS elevated in

1. Abortion incidence of

sibships T
T vs. OE
1. Shortened IPG OE
2. Febrile illness T

146

147

LS vs. OE elevated in

1. Abortion incidence in

sibships OE
2. Anti-emetic usage OE
3. Maternal hormonal usage OE
4. Shortened IPG OE
5. Conception after abortion

frequency OE

Differences which reflect significant etiological fac-
tors were found by doing inter-group comparisons. These
were as follows:

T vs. control

1. Febrile illness T
2. Anti-emetic usage T

LS vs. control

1. Febrile illness during first

two months LS
2. Blood type B frequency LS
3. Blood type A frequency control
4. Incidence of pyloric sten—

osis in relatives controls

OE vs. control

1. Incidence of abortions in

sibships OE
2. Anti-emetic usage OE
3. Hormone usage OE
4. Gynecological problems OE
5. Shortened IPG OE
6. Conception after abortion

frequency OE

T vs. siblings

1. Febrile illness during first
two months T

LS vs. siblings
1. Febrile illness LS

2. Anti-emetic usage LS
3. Oral contraceptive usage LS

148

OE vs. siblings elevated in
1. Hormone usage OE
2. Shortened IPG OE
3. Conception post ab OE

Another accomplishment of the study was to demonstrate
that clefting and hydrocephalus are more frequent among the
siblings of NTD probands, when the data from the literature
survey were pooled.

In conclusion, this study has demonstrated that hetero-
geneity apparently exists between different levels of NTD.
One basis for the heterogeneity could be based on embryolog-
ical occurrences such that T and LS type defects could be
caused by neural tube non-closure whereas OE type defects
could be the result of neural tube rupture. This would ex-
plain not only the heterogeneity observed in this study, but
the inconsistencies between previous studies. Hopefully new

avenues of research have been suggested for the future.

APPENDIX A

FAMILY HISTORY

149

KEY TO ABBREVIATIONS AND SYMBOLS
USED IN APPENDICES OF FAMILY HISTORY

Abbreviations:

ASB = Anencephaly and/or Spina Bifida
CHD = Congenital Heart Defect
PS = Pyloric Stenosis

CE = Clubfoot

CLP = Cleft Lip/Palate
Symbols:

# = number

0 = degree relative

0 = negative history

+ = positive history

- = not available or unknown

150

 

 

m N m H o o o o 0 mm MH q NH
0 o o o o o 0 HM o q HH
0 o o o o o m N mN w q OH
o o o o o o 0 NM w m m
o o o o o o o NH HH m m

N H

H N o o N H o o 0 ON a q n

N H o o o o o o mH m m o

N c o o o o o 0 MN m m m

H H o N H o o o q H no ON a w

m H

H q o o o o o H H mm OH m m
H
o o o o o o o Nq 0H m N
o o o c o o 0 mm OH w H

o a o H 0 1H 0 1H 0 a.» o «H o i.»

mU<Hmm<omH£ mHU mo mm Qmu mDH<mmmoomnwm mm< QMHSH OZOUMm HmmHm * .Hm
"mo wmoemHm wHH2<m mm>HH<Hmm ho mmmzaz

mumn :meson I oHomuonH "macaw

 

wMOHmH: MCHHHSNM

 

151

 

H H O O O O O O we OH q OH
H N O O O O O O «N m m OH
H N O O O O O O mN m q NH
O H m H m m O O O O I I N OH
O O O O O O O OH c m mH
O O O O O O O mN m N «H
O O O O O O O ON c N mH
N N
N H O O O O O N H MO mH N NH
O O O O O O O mm O q HH
m H
N N O O O O O O «N w m OH
O O O O O O O on OH q o
N H O O O O O O mm m N m
m H O O O N H O O Nq NH N N
O O O O O O O HO NH N O
H H O O O O O O HN mH N m
O O O O O O O O ON O ¢ q
O O O O O O O O OH O N m
H ¢ O O O O O O ON m N N
O O O O m H O O NH O N H
o «H o a» o a» o H» o a» o a o H
mw¢Hmm¢umHz mHU mu mm Qmo mDH<mmmoommwm mm< OmHmH QZOUMm HmmHm N .H@
mm>HH<Hmm mmmwma mam .QZN .HmH ozoz< MMOHmHm VHHZ<M mm>HH<Hmm ho mmmZDz

mumn .m .D I oHomuonH ”mDOMO

 

meHmHm wHHz<m

152

 

 

o o o o o o a H No 0H s 0N
N H o o o o o o H NN oH N NH
N N o o o o o o NH NH N NH
N H
H H o o o N H o o NN HH m NH
0 c o H H o o o «H oH N 0H
N N
H o o o o o o NN N N NH
o o o H H c o 0 mm HH N «H
o o o o o o o NN OH H NH
H N o o o o o o HN N N NH
H H o o o o o. o NN NH a HH
o o o o o o o «N N s 0H
0 o o o o o o NH N N N
N m o o o o o o NN a N N
o o o o o o o NN OH H N
o o o o o o o Ha N N o
H H o o o o o o NN NH N m
o o o o o o 0 NH NH N a
o o o o o o o NH 0 a N
o o o o o o 0 mm N N N
H N o o o N H o o NN N N H
o a o H» o N o H o H o a o H
mo<Hmm<oNHz NHo mo NN amo NpHamNmoomaNm mm< amHmN nzoomm NNNHN N .HN
“No NmoamHm NHH2<N Nm>HH<Hmm No mmmzsz
moan ammHnon . umnasH “Naomo

 

MmOHmHm NHH2<R

 

153

 

w H
m N m H O O O O N H mm HH N mm
N m
H H O m m O O O O m« MH « mm
H H O O O H H O O o« OH m Nm
H H O O O O N H O NN m m cm
O O O O O O O Om MN « mm
O O O O O O O HN w « «m
O O O O O O O mm mH N mm
H H O O O O O O Om N m Nm
m H O O O m H O O N« MH m Hm
m N
H H O O O O O O O« «H m on
N N O O O O O O HN O m ON
O O O O O O m H MN m m ON
m N m m
H H O O O N H « H O Hm w « NN
H N O O O O O N N NH HH « ON
O O O O O O O m N « mN
O O O O O O O O« OH m «N
O O m H O O O O mm HH N mN
N H O O O O O m N HN O m NN
N H O O O O O O OH O « HN
o H» 0 «H 0 NH 0 H» 0 NH 0 H» o H»
MO4Hmm<omHE mHU mu mm nmo mDH<mmmuomnwm mm< QmHmH Ozoomm HmmHm § .Hm
”mo MMOHmHm WHHE<m mm>HH<Hmm ho MmmZDz
Au.coov mama cmeson I HmnaaH umbomo

 

WMOBMHm

MHH2<m

154

 

 

H O O O O O O O OH OH O OO
O O O O H H O O OO mH N O«
N H
H H O O O O O m H ON OH O O«
O O O O O O O O« OH O N«
O O O O O O N H NO O n O«
O H
N H O O O O O m H «N O « m«
N N O O O O O N H O« NH N ««
O O O O O O O «H O m m«
H H O N H O O O O mm OH O N«
O O O O O O O Om OH O H«
O O O O O O O «« NH O O«
o «H o H» o H o «H o H» o H» o «H
OOOHOOOOOHZ mHO mu Om emu ODH<mmmOOmnwm Om< OmHmH Ozoomm HmmHm O .HO
"mo NOOHOHO MHszm mm>HH¢Hmm mo mmmzbz

Hu.coov mama ammHnon I unnasH "macaw

 

NmOHmHm WHHZ<m

155

 

 

O O O O O O N H HN NN N ON
O O O O O O O NO NH N NH
O O O O O O O NH N N NH
O O O O O O ON N N NH
O O O O O O O NH N O NH
N H O N H O O O O NN OH N NH
O O O O O O N H HO OH N OH
O O N N O O O O H NN N N NH
O O O O .O O O NN OH N NH
N N O O O O O O NH O O HH
N H O O O O O O NN OH N OH
H H O O O O O O HN N N N
OH H
N H O O O O O N H NN HH N N
N H
H N O O O O O O H HH HH N N
N H
H H O O O O O O ON N N N
O O O O O O O ON N N N
H H O O O O O O NH N N O
O O O O O N H O NN HH N N
N N O O O O O ON HH O N
O O O O O N H O HN NH O H
o «H. o «H. o O 0 NH 0 N o N. o N1
NONHNN<ONHz NHO NO ON ONO NOH<ONNOONONO NON ONHON Ozoomm NNNHN O .NN
“NO NNONNHO NHHzNN Nm>HN<Hmm NO Nmmzpz
«ONO .N.O I NunasH “NOONO

 

MMOHOHS VHHZ<m

 

156

 

 

N H

H H O O O O O O «H O m H«
O O O O O O O ON O N O«
O O O O O O O NO «H N on
O O O O O O O O N O OO
O m H . O O O O O NO O N NO

H O O O O O O O Om O N Om
O O O O O O « H NH « N mm

H H O m H o m H O O NO N m «m

H H O O O O O O NH O O NO
O O O O O O O NH O O NO
O O O O O O O N« OH N HO
O O O O O O O NH O N on
O O O O O O m H N« HH m ON

N N O O o o O O ON NH N ON
O O O O O O O m« HH m NN

H H O O O O O NO NH « ON

H H O O O o O O ON O « mm

m H

H H O O O O O N H HN m N «N
O o O O O O O «O OH O ON
O O O O O O O N« NH O NN

N H O O O O m H m H ON O m HN

o N o N o N o N o N o H o H

mO<Hmm<OOHZ OHO mo Om Ono OOHdmmmoomme OO< QOHOH ozoomm HmmHm O .HO
"mo MOOHOHO wHHz<m mm>HH<Hmm mo OMOZDZ
Au.coov mama .0.0 I HOOEDH umbomw

 

VMOHOHm MHHZ<M

 

157

 

 

O O o o o o o 0 ON O O OO
H H o o o o o 0 ON O O ON
H H o o o N H o o NN O O NO
0 o o o o o o OO O O HO
N H o c o o o o HO HH O on
o o o o o o o O NH O OO
N N o o o o o O H ON O N OO
H H o o o o o o NN N O NO
N H o o o o o c HN O N OO
o o o o o o 0 OO O O NO
o o o o o o o ON NH O OO
o o o o o o o OO O O OO
o o o o o o o NN O O NO
0 O o O o O» o O o O o O o O
OOOHOOOUOHz man no ON nmu OOOOONNUOOOOO OOO OOHON ozoomO HOOHN O .Nm
"mo OOONOHO OHHSOO OO>HHOHOO mo Ommzpz
Au.aouV muma .O.: n umnasq "Naomc

 

WMOHmHm NHHZ<W

 

158

 

 

o o o o o o o ON O O N
H H o O H o o o H H 0N O O O
o o o o o o o NO OH N O
H H o o o o o o ON O O O
o o o o o o o NO NH O O
o o o o o o H H O O . O N
H H o o o o o o OH O N H
o O o O o O o O o O o O o O
OOOHOOOOOHz ago no Om amo OONOOOOUOOOOO OOO OOHOO azoomm HOOHO O .HN
"mo OOOOOHO OHHzOO OO>HOOOOO no OOOzpz
mumn cmOHOUOz . HmuomO “mpomo

 

VMOHmHm VHHZ<m

 

159

 

 

O O O O O O O HN OH O NH
O H

H H O N H O O O O H NOH OH O OH
O O O O m H O m H OH O O OH
O O O O O O O NO HH O NH
O O O O O O N H HO O N HH
O O O O O O O Om OH N OH
O O O O O O O ON n O O
O O O O O O O Om NH N O
O O O O O O OH OH N m

m O

N H O O O O O N H HN n N O
O O O O O O O OO OH O O
O O O O O O m H ON 5 O O
O O O O O O O NO O O O
O O O O O O O OO OH O N
O O O O O O O HN O O H

o O o O o O o O o O o O o O

mO<Hmm<omHz OHO mo mm emu mDH<mmmoOmawm mmfi OmHmH azoomm HmmHm O .HO
"mo OMOHOHE VHHS<O mm>HH<Hmm mo ammZDz
mama .m.D I Hmuumm umbomu

 

WMOHmHm.WHHZ<m

160

 

 

O O
H N O H O H o O H o o HO O N HH
H H o o o o o o OH O O oH
H O o o o o o N H OO OH O O
H N o o o o o o O O O O
H H o o o o O H o NN O O O
o o O H o o o o NO NH N O
O H c o o o o o NN NH N N
o o o o o o O H I I O O
N H o o o o o 0 ON O O O
o o o o o o 0 ON O N N
H H o o o o o o OO O N H
o O o O o O o O o O o O o O
moOHOOOOOHz ONO mo Om emu NDNOOOOOOOONO ONO OOHOO nzoomm ONOHO O .OO
"mo OOoNOHO ONH2<O NO>HO<HOO No OOOZOZ
mama cmOHOUOz u “mane "maomu

 

wmoamHm WHHZ<M

161

 

 

H O o o o N H o 0 ON O ,N O
N H o o o o o o HO O O O
H H o o o o o NO O O N
O N
H H O H o o O H o o OO NH O H
o O o O o O o O o O o O o O
OOOHOOOONHz OOO mo NO Omu NONOOOOOOOOOO ONO OOHOO Ozoomm HNOHO O .OO
“mo OOOOOHO ONHOOO OO>HOONNO mo OmOzaz
mama .N.: u umguo "Opomo

 

NMOHmHm MHHZ<h

162

 

 

O O O O m H m H O NO NH O O
N N
H H O O O O O O NO O N O
m H
N H O O O O O O OH HH N N
N O
H H O O O O O O OO O O O
H N O O O O O O HN O O O
O O O O O O O Om O N N
O O
N O
H N O O O O O O ON O m H
o O o O o O o O o O o O o O
mO<Hmm¢OmHz OHO mo mm omo ODH<mOmOOmme Om< OmHmH Ozoomm HmmHm O .HO
"mo MOOHOHO NHHE<O Om>HH<Hmm mo mmmzbz
name amenon I mHmuonnamucm “ODOOO

 

WMOHmHm MHHZ<h

163

 

 

O O O O O O O ON O O ON
H H O O O O O O ON OH O OH
N O O O O N H O O OO O O OH
H H O O O O O O ON HH O OH
N H O O O O O O ON O N OH
O O O O O O O ON N O NH
O O O O O O O OO OH O OH
O O O O O H O O OO OH N OH
O O O O O O O OO OH N NH
N H
H H O O O O O O OH O O HH
O O O O O O O HN O N OH
O O O O O O O OO NH O O
O H
N H O O O O O O OO HH O O
O O O O O O O NO ON O O
N H O O O O O O OO O O O
H H O O O O O O ON OH O N
H H O O O O O O OH O N O
H H O O O O O O NO O O O
N O
H H O N H O O O O HO HH O N
H H O O O O O O NH O N H
o O o O o O o O o O o O o O
MO<HMO<UOHZ OHO mo Om Qmu ODH<mmmoomme OO< QmHmB azoomO HOmHh O .HO
”mo OOOHOHO VHHZ<m mm>HH<Hmm mo OOOZDZ
Houucou ”ODOOO

 

WOOHOHm MHHZ<m

 

164

 

O O O O O O O I HH O NO
O O O O O O O H OO O O HO
H O O O O O O O ON NH N OO
O O O O O O O OH OH O OO
H N O O O O O O NH N O OO
O O O O O O O OH O O NO
O O O O O O O HN OH O OO
N H
H H O O O O O O NN HH O NO
H H O O O O O ON O N OO
O O O O O O HO OH N OO
O O O O O O N H NN OH O NO
O O O O O O O ON O O HO
O O O O O O O ON N O OO
O O O O O O O ON NH N ON
H N O O O O O O O N O ON
O O O O O O O ON O O NN
H H O O O O O O ON OH O ON
H H O O O O O O OH O O NN
H N O O O O O O HN O O ON
N H O O O O O O OO O N ON
O O O O O O O OO OH O NN
O O O O O O N H OO OH N HN
o O o O o O o O o O o O o O
mu<Hmm<omHZ mHU m0 Om emu ODH<mmmoomawm OO< QMHSH onumm HOmHm O .HO
”mo MMOHOHm NHHZ<M OM>HH<HMM mo MMOZDZ

Au.aoov Houuaoo "OOOOO

 

MMOHOH: NHH2<h

165

 

 

O N

o o o o N N o o OO OH O ON

O H o o o o o O H OO O O mm
o o o o o o o NN O O NO
0 o o o o o 0 NH N N ON
o o o o o o 0 ON O N mm
o O H O H o o o o HO OH O ON

O H o o o o o 0 ON OH O OO
O O O O O O O OH N N NN
o o o o o o o HN HH O HO
0 o o o o o o HO N O on

N H O O O O O O HN OH N OO

H H o H H o o o O H HN OH N OO
o o o o O H o 0 OO N O NO
I I I I I o o ON O O OO
O O O O O O H O NN O N NO

O H

N H

H H O O H O O O O ON N O OO
o o o o o o o NO OH O OO

0 O o O o O o O o O o O o O

mu<Hmm<OmHz mHo mo mm OOO ODH<mmmOOmme Om< OmHmH OZOOOO HmmHm O .HO
"mo NMOHOHO wHHz<m mm>HH4Hmm mo MOOZDZ
Au.aoov Houucou "mbomo

 

MMOHmHm VHHZ<m

APPENDIX B

PREGNANCY HISTORY

166

KEY TO ABBREVIATIONS AND SYMBOLS
USED IN APPENDICES OF PREGNANCY HISTORY

Abbreviations:

* = proband
ab = abortion
B.D. = birth date (month-year)

CC = oral contraceptive usage

time time of infection
Anti-em. = anti-emetic usage

other = other medications

Symbols:

# number
= degree relative

negative history

-+ O o
u

= positive history

- = not available or unknown

 

167

 

ON + o .a OOH + .e OOH + o + IN O 2*

OH o o + o o o IN O O

O o o + o o o IH N N O
I o o + o o o H Om

OHH o + o o o o O NO

ON 0 + O o + o N OO

O o + o o + o O OO

OH o + o o + o O O

ON 0 + o o + o O N O
O o + o o + o O O

NH o + o o + o N pm
I o + o o + o H Om

OO o o o o o o OOIOH m I

NH o o o .a OON + o 0 IO N :O N
I o o o o o + H Om

OO o o o o o o IN N NO

ON 0 o o o o o IOH O O

OO o o o o o o IHH O 2

ON 0 o o o o o IOH O z

o o o o o o o IHH O O H

O o o o o O H IN N z
I o o o o o o IO H m

OOH Ommeo .zNIHNZO mzHN mmmzng mzHN DON mmzozmom oo .a.m O .OO xmm O .NN

«Own OOONOUN: I UHomuoON "Noomo

 

NmoemHm NOZOZONOO

168

 

 

NN O O O .a NIH + o O IO O OO

HH O O O O O O IO N O OH
I O O O O O O IOH H m

NH O O O O O O IO O I
HH O O O O O O IO O I
HN O O O .mOB N + O O IN N m« O

I O O O O O O IH H I

NN O O O O O O IOH N 2*

I O + O O O O IO H E O
00 I... O O O O + IH m Wyn

NN O O O O O O I O am

NH O O O O O O IO O m N
NH O O O O O O IN N z

I O O O O O O I H mm
HN O + O O O + IN N mO

I O O O O O O IO H O O
O O O O O O O N I
I + + O O O + IN H m« N
OOH OmmHo .zmIHHz< mzHH mmOZQHH OSHH Dam mmzozmom 00 .0.0 O .OO NON O .HO
Nu.couV mama amwwnowz I oHomuozH umOOOO

 

MMOHOH: woz<zummm

169

 

 

I O O O O O O O I
I O + O .E NIH + O O N m« NH
I O + O O O O H I
OO O O O O O O IO O I
O O O O O O O IO N I HH
.xcs
I + O O mBHu + O O INH H 2*
omH mmmeo .SMIHHZ< mzHH mmmquH OZHH DHm mmzozmom UO .O.m O .wm me O .Hm
Au.c00v mama amOHOUHz I oHomuone umpomo

 

wMOHmHm woz¢zummm

170

 

.xc:

 

I + O mEHu + O O O NNIO H 2* O
I O + .mxs O + O O O ONIO H I« N
I O O O O O O ONIOH H 2* O
O O + O O + O ONIN N 2*
I O + O .a N + O O ONIH H an N
HN + O O O O O ONIHH O m«
Hq + O O O O O OOIN N 2 v
I O O O O O O OOIO H z
I + O O O O + H m« O
I O O O O O O N am
I O O O O O O O pm
I O O O O O O O nm N
I O O O O O O N am
I O O O .8 N + O O ONIHH H Ex
I O + O O O O IH H m« H
omH mmmHo .ZOIHHZ< mzHH mmmZHHH mzHH DAN mmzozmom OO .o.m O .Om xmm O .Hm
wumn .O.D I UHumuonH "macaw

 

MMOHOHS Moz<z0mmm

 

171

I O O O O O O ONIO H HH« OH

«m o O O o wcHuuoam + + «NIm N .m«
I o o o o o + HHIN H z mH
I O + O O . O O H I* OH
I O O O O O O ONIO H m* OH
ON + .8 N + OHou .mxB N + .8 N + + O ONIN N m«
I O O O .8 OIN + O O NNIN H Om NH
NO + + O .m&3 c + O O ONIO O z«
HN O + O O O O ONIO N h HH
I O + O O O O OOIO H m
NN + + umouOu Omuum + .8 OIN + O O OOIO N m*
I O + O O O O NNIO H O OH
O O O O O O O HNIOH O O
O O O O O O O ONIN N m m
I + O O O O O OOIO H m«

 

omH mmmHO .ZMIHHZ< mZHH OOMZHHH mZHH DHm mmzozmom UO .Q.m k .Um mum * .Hm

Hu.aoUV mums .m.O I UHumuonH “macaw

 

WMOHmHz Woz<zummm

 

172

 

OO O + O O O O ONIHH q S

NN O + O O O O ONIO O m

ON O + O O O O HNIN N hi OH
I O + O O O O NOI H am

ON O + O O O O OOI q 2*

I O O O O O O NOI O am
I O O O O O O OOINH N O OH
I O O O O O O OOI H am

HN + O umounu .8 N + O O O OOIO N I
I O O O O O O NNIO c I
I O O O O O O O Ow NH
I + O .8 OCN + O O O HNIO N m«
I O O O O O O H pm

OOH mmmHO .ZMIHHZ< mZHH mmeHHH mEHH OHm OMZOZMOm Do .Q.m O .OO Nmm O .HO

Hu.coov mama .m.: I UHomuose “maomo

 

wMOHmHz wuz¢zwmmm

173

 

 

HH O O O O O O IN N O

I O O O O O O IH H 2* O
OH O O O O O O INH N OO

OH O O O O O O IN O O

OO O O O O O O I O OO

OH O O O O O O IHH O O O
OH O O O O O O IN O O

OH O O O O O O IO N O

I O O O O O O IO H O

O O + O O O O IO N z

I O + O O O O IN H z« O
OO O O O O O O IO O I

OH O O O O O O In N I O
I O O O O O O IO H O«

I O O O O O O IHH H O« N
HN O O O O + + IHH O NO

ON O -O O O O O IO O 2
O O O O O O O In N am H
I O O O O O O IO H Om
OOH OOONO .zOIHHZO OzHa OOOZHHH mzHe OOO OOZOzOOO OO .0.0 O .OO ONO O .NO

mama cmOHOUHz I umnasq "OOOOO

 

VMOHmHm woz<zwmmm

 

174

OO O + O O O O IN N *mIm

I O O O O O O IO H 2 OH
O + O O O O O IO O m«

ON O O O O O O N am NH

I O O O O O O H OO
O O O O O + O INH O O
OO O O O O + O INH N m HH

I O O O O + O IHH H OO
OOH O O O O O O IN N 2*

I O O O O O O H 2 OH
O O O O O O + IO H 2« O
NO + + O O O + IH O 2*

O + + O O O O IO O O
NH + O O O O O IN N 2 O

I + O O O O O IO H m
HN + O O O O + IO O OO
NN O O O O O + IN N z N

I O O O O O O IN H z

 

OOH mmmHo .ZmIHHZ< mXHH mmmZHHH mZHH DHh mmzozmom UO .Q.m O .O@ Nmm O .HO

Au.coov mumO GOOHOUOZ I HOOBSH umDomO

 

VmOHmHm Woz<zummm

175

 

 

NH O + O .a OOH + O O IHH O 2*
NO O O O + O O IO N I HN
I O O O O O O IO H O
NN O O O O O O IH O 2*
OO O O O O O O IO N O ON
I O O O O O O IHH H z
HH O O O O O + IHH N z
I O O O O O + IH H OO OH
.38:
I O O O maHu + O O H OO OH
I O O O O O O O O«
I O O O O O O O I
I O O O O O O O I NH
I O O O O O O N I
I O O O O O O H I
I O O O O O O IO H OOIN OH
I O O O O O O IO H N« OH
ON O O O O O O IO N z
I O O O O O O IO H OO OH
OOH OOONO .OOIHNZO OzHO OOOZOHH OOHN OOO OOZOOOOO OO .O.O O .OO NOO O .NO
AUOGOUV NHGQ fimwflfiUfiz I HQQSDQ “OH—HOMO

 

WMOHmHm.MQZ<ZomMm

176

 

 

I o o o o o o m I
wH + o o o o 0 Im O z*
N o o o o o o N am NN
N o o o o o o N am
I + o o o o o H z
o o o o o o o m m«
mO o o o c o o O am
mH o o o o + 0 Im m m ON
I o o o o o o N am
I o o o o o o INH H m
cm 0 o o .8 N + o 0 IN N MO
mu 0 o o o o o IO N m mN
I o o o o o o Io H z
O o o o o o o IHH O z
o o o o o o o IoH m x
O o o 0 .mx3 w + o o IN N m« ON
I o o o o o 0 I0 H z
o o o o o o o IN H 3% mN
NH O o o o o o INH N m
.m&3 O
I o + wHou + o o 0 IN H 2* NN
omH mmmeo .ZMIHHZ< mzHH mmMZHHH mzHH :Hm mmzozmom uo .n.m O .um xmm O .Hm
Au.:00v mama ammHnon I umnfisH “macaw

 

WMOHmHm Nozfizummm

177

 

 

I o o o o o + IHH H h* mm
mN o o o o o 0 IO m z
m o o o o o 0 IO O m
mH o o o o o o IOH m 2 NM
O + o o o o o INH N 2*
I o o o o o o IHH H m
.xcs
I o o o waHu + o o Io N m*
I o o o + o o H 2 HM
I + o o o o + m 2*
m o o o o o o N am om
I o o o o o o In H m
HN o + o + o o IN N I
I o + a m cHou + o o o IH H m« mN
OH o o o o o + Io O 2
NH o o o o o + Iw m 2
OH O o o o o + IOH N m« mN
I o o o o o + Im H m
omH mmmeo .zmIHHz< mzHH mmMZHHH mzHH DHm mmzozmom oo .a.m O .om xmm O .H&
Au.co0v mama cmeSUHz I quSSH “mpomu

 

WMOHmHm Noz<zummm

178

 

 

I o + o o o o H MO mm
nN o o o + o o IOH O 2*
Nm 0 o o o o o In N z
I o o o o + o INH N m mm
I o o o o o o H pm
mNH o o o o o 0 Im n 2*
OH o o o o o o In O m
cm 0 o o o o o IO N 2* On
I o o o o o o IH N m
I o o o o o o H pm
ON 0 o o o o + IO N 2*
wH o o o o o 0 IO N E on
I o o o o o o IH H mm
m o + o .E N + o + In m 2*
HN o o o o o o IHH N 2 nm
I o o o o o o In H z
I o o o o c 0 Im N m
I o + o o o o IH H «SI: Om
omH mmmyo .zmIHHz< mzHH mmmZHHH mZHH DHm mmzozmom oo .m.m O .um me O .H&
Au.coov wumn :menon I umnasH "macaw

 

wMOHmHm woz<zommm

179

 

 

I o + o .8 N + o o H :« OO
mn o o o + o o IHH N z
.5 NIH
I o o um>mm + o o + H 2« MO
m o o o o o o IH w m
ON + o o o o 0 IO N MO
H o o o o o 0 IO 0 z
O o o o o o o I n nm
N o o o o o 0 IN O 3 NO
n o o o o o o IOH m z
o o o o o o o Iw N m
I o o o c o o In H z
w o o o o o o INH N z
I o 0 .mx3 9 once + o o o IN H 2* HO
.xcs
mn o + o maHu + o + Io O m«
N o o o o o 0 IO m I
HO 0 o o o o o INH N I 0O
I o o o o o o IOH H I
omH mmzeo .ZmIHHz< mzHH mmMZHHH mzHH DHm mmzoxmom oo .a.m O .om xmm O .Hm
Au.aoov mama cmmHSUHz I umnasH umbomu

 

VMOHmHm woz¢20mmm

180

 

 

I o o o o o o n z
I o o o o o o O m
MN 0 o 0 .mx3 O + o o IOH m m« mO
I o o o o o o N m
I o o o o o o H m
HH 0 o o o o o IN n m«
I o o o o o o I O pm
NH o o o o o o IHH m 2* OO
n o + o o o 0 Im N I
I o o o + o 0 IN H I
mH o + o o o o INH N I
I o + o o c + IH H OO NO
0O 0 o o o o o IH O I
OH o o o .a NIH + o 0 IO m m«
OH 0 o o o o o IH N I OO
I o o o o o 0 Im H I
O o + o o o 0 IO m 2
cm 0 + o o o o In N 2* nO
I o + o o o o INH H m
umH ammwo .ZMIHHZ< mzHH mmmZHHH mzHH DHm mmzozmom uo .a.m O .um .xmw O .Hm
Hu.:ouV wumn cmesUHz I umnaaq “maomu

 

OmoemHm OOZOzummm

181

 

 

I o o o o o o OH I
I o o o o o o O I
I o o o o o o w I
I o o o o o o N I
I o o o o o o O m«
I o o o o o o n nm on
I o o o o o o O I
I o o o o + o m I
I o o o o + o N pm
I o o o o + o H pm
omH mmmHo .ZMIHHZ< MZHH mmmZHHH mZHH DAM mmzozmom oo .m.m O .Um xmm O .Hm
Au.c00v mama cmeson I umnEDH umDomo

 

OmoemHm.wuz<zummm

 

182

 

 

I o o o o + + ONIO m 2*
I o o o o o o N nm N
I o o o o o o H pm
mN o o o o o o HNIN m m .
ON 0 o o o o o NOINH N 2* O
I o o o o o o H pm
I o o o o o o owIO H 2* n
om o o o o o o m am
On 0 o o o o o ONINH N m* O
I o o o o o o mOIm H S
m o 0 .mx3 nIO + o o o wNIN N 2%
I o o o o o o NNIN H m m
I o o o o o o m I
I o o o o o o nOI N m* N
I o o o o o o H I
mH o + o o o o mOIO m z
w o o o o o o OOINH N m H
I o o o o o o nOIn H 3*
omH mmmao .ZmIHHz< mZHH mmmZHHH MZHH DHm mmzozmom UO .Q.m O .Um NMm O .Hm
Mama .m.D I HmnEDH umbomu

 

VMOHmHm Wuz<zcmmm

183

 

.xa:

I o o 0 mafia + o o mNIHH H O OH
O o o o o o o owIM O M
I o o o o o + MNIN M Z
I o + o o o + I N M« MH
I o o o o o + NNIO H 2
I o o o o o o ONIHH H 2% NH

MO 0 o o o o o ONIN M 2%

nN o o o o o o NNIM N z HH
I o o o o o o mOIn H z

+ooH + + o o o o nNI O M«

NN o + o o o o NOIH M 2

O o + o o o o man N M OH
I o + o o o o anm H M

nH o o o o o o nOIM M 2

OH o o o o o o MOIM N an m
I + o 0 .mx3 OIH + o o HOIHH H .z«
I + 0 0 .HH» umH + o o ONIH H 2* w

 

UMH mmmHo .XMIHHZ¢ mZHH mmmZHHH mZHH DHM mmzozmom UO .Q.m O .UM me O .HM

Hu.aouv mama .O.p I unnasa “macaw

 

NMOHmHm Woz<zummm

184

 

 

I O + O O O + OOIO H «:Iz ON
+ON + + O O + O NNI N 2*
I O + O O O O ONINH H z NN
ON O O O O O + ONIO N z
I O O O O O + ONINH H 2% HN
I O O O .5 N + + O ONIN H O« ON
I O O O O O O ONIOH H O« OH
I O O O O O O ONIH O 2*
I O O O O O O ONI N am OH
I O O O O O + HNIN H 2
OH O O O .OOO OOH + O O OOIHH N OOO
I O + O .a O + O + ONIN H 2 NH
N O O O O O O ONIO O OO
HO + O O O O O NNIO N I OH
I O O O O O O OOINH H I
OH O O .OO: O O O + NNIHH N O
I O O mafia + O O + ONIN H zO OH
OOH OOOOO .xOIOOZO OzHO OOOZHOO OzHO OOO OOzonOm Oo .O.O O .OO xOO O .OO
Nu.cooO mama .0.0 I Omnasg "OOOOO

 

WMOHmHm wuz¢zommm

185

 

 

I o o o o o o MNIHH H MO cm
I + o o o + o ONIN H MISO ON
on o o o o o o OOIOH O MO
N o + o o o o NnIN M M
O o o o o o o OnIm N M ON
I o o o o o o nnIN H 2
MN 0 o o o o + ONIO N M«
I o o o o o o nNINH H M NN
NH 0 o o o o o ONIH O a«
ON 0 o o o o o NNI m an
OH o o o o o o ONIO N M ON
I o o o o o o NNIN H z
I o + o o o o O MO
O o o o o o o OOIO m z
O o o o o o o OOIO N M nN
I o o o o o o H on
.uamucoo
O + O I OH00 + O + O ONIN N OO
I o o o o o o H mm ON
OMH mmmHo .ZMIHHZ< OSHH mmMZHHH mzHH DHM mmzozmom uo .D.m O .OM xmm O .HM
Au.:oov mama .O.D umOSSH "MDOMU

 

WMOHmHm woz¢zummm

186

 

 

OO O O O O O O ONIOH N 2*
I O O O O O O NNIN H O OO
I O + O .OO3 O + O O OOI H OO NO
I + O O O O O ONINH O 2*

I O O O O O O NNI O am
I O O O O O O N Om OO
I O O O O O O H Om
.xc:
I O O O mafia + O + H O« OO

O O + .a O + O + O ONIOH O O«

N O O O O O O ONINH N am OO
I O O O O + O ONIO H O

OH + O O O O O ONINH O 2*

I + O O O O O N am OO
I O O O O O O NNIO H 2

NO O + O O O O ONINH N O«

I O O O O O O NNIO H 2 NO
I O O O O + O H 2* HO
OOH OOOOO .ZOIHOZO OzOO OOOZOOO OzOO OOO OOzonOm OO .O.O O .OO xOO O .OO

Hu.couv OOOO .O.O I OOOasg “OOOOO

 

wmoamHm NUZ<ZUMMM

187

 

 

ON 0 o o o o OnIN m 3*
N + o o o o o onIOH N 2 OO
.xc:

I o o o meOu + o o OOIO H M

OH + + o .a N + o o ONIn N z«

I o o .a N + o o + NNIH H 2 OO
I o o o o o o m MO

on o o o o o o OOIOH N M MO
I o o o o o o nOIHH H M

I o + o o o o NNI O M«

OH o o o o o + ONIO N M NO
I o o o o o o HNIHH H z

O o o o o o o OOIn O SIS

ON 0 o o o o o ONIOH m pm

HN o o .a H + o o o ONINH N M HO
I o o o o o o oNIO H 2*

OO + + o .a O + o o nNI N 2*

I + + o + o o HNIN H M 0O
I o + o o o o H 2* mm
OMH mmmHo .ZMIHHZ< OZHB mmMZHHH MzHH DHM mmzozmom oo .Q.O O .OM me O .HM

Au.a00v mumn .m.D I HOLESH "MDOOO

 

MMOHmHm Wuz<zommm

188

 

 

OH O OHoU .a H + O O O ONIO O OO
ON + O .OO9 + O O O NNIN O I
HO + O mafiu + O O O ONIO N I NO
I O O O O O O OOIO H Om
I O O O O O O NNINH H O HO
NO O O OHO .s H + O O O ONIHH O OO
NN O O O O + O ONIH N O OO
I O O O O O O NOIO H O
OH I I I I I I NOINH O O
OH I I I I I I OOIO N O« OO
I I I I I I I OOIO H O
.35:
I + O O OsOu + O O ONIN H :O OO
OH + O O O O O OOIO O OO
.xc:
I O O meOu + O O + ONIO O O
I O O O O O O I N OO NO
I O O O O O O OOIOH H O
I O O O O O O NNI H O« OO
OOH OOOOO .zOIHOZO OzHO OOOZHHH OzHO OHO OOzonOO OO .O.O O .OO xOO O .OO
Hu.aouv OOOO .O.O I Ompasq "OOOOO

 

MMOHmHm WUZdzommm

189

 

 

OH + + O O O + ONIO N 2*
I O + O O O O ONIHH H 2 OO
O + + O .s NIH + O O ONIO O 2*
ON O O O O O O NNIN N Om OO
I O + O O O O ONIHH H O
OOH OOOOO .zOIHOZO OzHO OOOzOOH OzHO :HO OOzonOO uo .O.O O .OO xOO O .OO
Nu.:ouv OOOO .O.O I Omnasq "OOOOO

 

MMOHmHm woz<zummm

 

>~.C.~.uJ. O... >nvz<zugw~ Z L

190

 

 

OH o + o o o o M I«

I o o o o o + IO N I N

I o o o o o + In H I

I o o o o o o O I

mm o o o o + o m z«

I o o o o o o N 2* O

I o o o o o o H am

I o o o o + + IH H MO n
ON 0 o o o o o M Om

HH 0 o o o o o IN N z O

I o o o o o c IO H 2*
OMH o o o o o 0 IO m MO

NN o o o o o 0 IO N x M

I o o o o O o In H 2
OH 0 o o o o o IO N M«

I o o o o o o IOH H M« N

O + o o o o o N M«

I o o o o o 0 mm H
OMH mmmao .ZMIHHZO OZHH OOMZHHH OZHH DHM mmzozmom uo .M.O O .OM xmm O .HM

muma cmOHnon I Hmuomm "Msomo

 

NMOHMHS WUZdzummm

191

 

 

+00 + + o o o + MMI q MO
MM + + o o o + MMIm m 2
O o o o o o o OOIO N M M
I o o o o o o NOIOH H z
.e NIH
I + o I wMou + o o o H MO O
NO 0 o o o o o oMIMH m MO
m o o o o o o OOIO N z m
I o o o o o o MOIO H 2
«M + + o o o o MMIM N MO
I o o o o o o OMIO H M O
OHM o o o + o o omIm m M
N o o o .e M + o o OMIOH N M m
I o o o + o + MOIM H MO
MO 0 o o o o o OMIH N MO
I o o o o o o mMIm H z N
I o o o o o o OMIM m M
I + o o o o o NMI N 2O H
I o o o o o o oMIm H z
oMM MMMMo .zMIMMz< MzMM mmszMM MzMM MAM mmzonom oo .M.M O .uM MMm O .MM
mumn .m.: I Hmpomm "Maomu

 

MMOHmHm Wuz¢zwmmm

192

 

 

HH O O O .a N + O O OmIM N 2O

I O O O O O O «nIN O z

I O O O O O O MOI M pm

OH O O O O O O OOIO q z

.xa:

HH O O O meHu + O O MOIN M M «H
N O O O O O O HOIHH N z

I O O O O O O OOINH H M

NH O O O O O O OMIO N MO

I O O O O O O OmIm H 2 MH

.8 H

m + + an“ “on + o o o mMIO N MO

I + O O O O O nnIHH H M NH
I O O O O O O NMIN H 2O HH
I O O O .E H + O O HnIN H MO OH
NN O O O O O + mmINH N zO

I O O O .a m + O + nnIm H z m

I o o o o o o OOI O H MO w
OMH Mmmeo .ZMIHHZ< mzHH OMMZHQH mzHH OHM mmzozmom oo .O.m M .UM xmm M .HM

Au.:ouv muma .m.: I Hmuumm ”MDOMU

 

MOOMmMM Moz<zummM

193

 

 

HM + O .mM3 MH + O O O OOIM N h?
I O O O O O O HnIM H z OH
OMH mmmeo .ZMIHHZ< MzHH mmMZHHH mzHH DAM mmzozmom OO .O.m O .OM xmm M .MM
Au.coov mama .m.: I Hmuomm “MDOMO

 

MMOMmHO Moz<zommm

 

194

I o o O o o o N I O
I O O O O O O H I
M o o o o o o omIM N 2
l + + O O O + anlm H h# m
OM o o o o + o M I
O o o o o + o N I q
uuma
I + o o MHumm + + o H MO
«N o o o o o o In M IO
OM o o o o o o IN N M M
I o o o o o o H z
I o o O o o o H 2O N
HH 0 o o o o o In q 2
OH + + O o o o IHH M M
.E N
H + + I OHou + o o o In N MO H
I O O O O O O H am

 

DMH mmmHO .ZMIHHZ< mEHH mmmZHHH mZHH DAM mMZOZMOm UO .Q.m * .UM Nmm M .HM

mumn ameLUHz I uwnuo “MDOMO

 

MmoemHm Moz<zummM

195

 

 

NN + + O O + + OOIM M MO
mH + O O O + O nnIO N am HH
I + O O O O + MnIO H Om
ON I I O O O O OOIN M M
M + + O O + O OOIOH N MO OH
I I I O O O O OOIOH H Om
ON O O O O O O m pm
ON O + O O O O O SO
ON O O O O O O M an O
OH O O O O O O N M
I O O O O O O H pm
I O O O O O O O Om
.OCM Mao
H + O .mxa M + O + O M IO
I O O O O O + O N am O
I O O O O O O H I
OO O O O O O O IM O 2
NH O O O O O O IM M Om
OM O O O O O O IHH N z N
.x:: weflu
I o o mOuOsuaoun + o o o INH H 2O
UMH mmmeo .ZMIHHZ< mEHB OOMZHHH mZHH DHM mmzozmom DO .Q.m O .UM Nmm O .HM

Au.:00v muma :mOHSUHz I umsuo

"MDOMU

 

MMQMMHOOMOzOZOOOM

196

 

 

I + o o o o o NMIOH M MO
I o o o o o o O OO

I o o o o o o O OO

I o o o o o o O OO O

I o o o o o o O OO
O o o o o o o MOIO N x

I o o o o o + OOIO H 2

OH o o o o o o HOIO m z

N + o o o o o OOIH N 2O m

I o o o o o o MOIm H M
HO o + o o o o OOIN O M
Hm + o o o + o ONI m MO
OH o + o o + o HNIO N M N

I o o o o o o H Om

I + o o o o o m MO

I o o o o o o N an H

I o o o o o o OOIO H M
OMH MMMMo .zmIHMz< MzHH OOMZOHH MzHM OHM OMzozmom uo .M.M O .OM MMO O .HM

«Own .m.: I Omnuo ”Macao

 

MOOMOHO.MOz<2OMMM

197

 

NH

0000000+ 00

0

0000

+-+-+

+-+-++-+-++-+ +-+

0

0000

.xc: mEHu
maeas

000

00

0000000+

.xc:
wEHu

0

0000

00000000 00

+

0000

00

0000000+

0

000+

00+00000 00

0

0000

OOIM
ONIOH
NNI

IO

M
N

HNNfil-fiOhw 00
H

H

HNMN‘!’

2O

am

pm H
M

 

OMH

MMMHO

.ZMIHHZ<

MZHH OOMZHHH

MZHH DHM

mmzozmom

numn ameDUHZ I meUOHmnamucm

Do

.o.m

O .UM xmm O .HM

"MDOMU

 

MMOMOH: Moz<zommm

198

 

 

NM O O O O O O HMIO O I
M + O O O O O OOIN M MO
O O O O O O O OOIN N M N
I O O O O O O OOIH H I
O O + + O O O OOIO O I
H O + .xc: + O O O ONI M MO
+ON O O mEHu + O O O ONI N am O
I O + OH00 + O O O ONINH H z
I O + O O O O H zO m
OMH OMMHO .ZMIHMz< MzHM OOOZHHH OZHH DAM mmzozmom OO .O.m .OM me O .HM
Au.aouv mumO dmOHnon I OHOUOHmanocm "MDOMO

 

MMOMOHM MonZOmOM

199

 

 

0O 0 o o .e OIO + o + OOIO N 2O
I o o o o o o ONINH H MO N
ON + + o o o + N I
I + + o o o o NNIO H OO O
O o o o o o o OOIO O I
HH 0 o o o o o ONINH N OO O
I o o o o o o ONIN H 2O
OO + o o o o o NNIO O 2O
O o o o o o o ONI N OO O
I o o o o o o ONI H Om
OO o o o o o o OOIH O OO
ON 0 + o o o o ONIO N OO O
I o + o o o o OOIO H M
H o o o o o o OOIN O I
OH o o o o o o ONIO N M N
I o o o o o + NNIO H MO
OH + + o o o o NNIO N zO
.xc: mEHu
I o o I OH00 + o o o ONIN H Om H
OMH OOOOO .zMIHMz< MzHM OOMZOOM OzHO DOM OMzonom oo .M.O O .OM xMO O .OM
Houuaou "Msomo

 

MOOHOHM,MOz<zOmmM

200

 

NH O O O O O O ONIOH M M

MH O + O O O O ONIO N MO OH

I O O O O O O ONIOH H M

I O + O O O O NNIOH H 2O MH

I O O O O O + ONIH H 2O NH

O O O O O O O ONINH M MO

H O O O O O O ONIN N Om HH

I O O O O O O ONIO H M

I + O O .E OIm + O O ONIO H MO OH

NN O O O O O O OOIM m I

ON O + .OMO N + O O O NNIM O MO

O O + O O O O ONIN M M O

HN O + O O O O NNIO N z

I O O O O O O ONIM H M

O O O O O O O OOIN N MO

I O O O O O O ONIHH H 2 O

OMH MMMHO .ZMIHHZ< OZHH OOMZHHH OSHH OHM mmzoZMom oo .a.m O .OM Nmm O .HM
Au.coov Houucou ”MDOMU

 

MOOMOHM MuzOZOMMM

201

 

 

OO o o o o + o OOIO N MO

I o o o o o + ONIN H M oN
OO O o o o o o ONIO O OO

NO 0 o o .s O + o o ONIN N MO OH
I o o o + o o OOIO H 2

OO o o o o o o OOIO O MO

OO o o o o o o OOINH O 2
oH o o o o o o OOINH O M OH
O o o o o o o OOIO N z

I o o o o o o OOIN H z

NN + o o o o o OOIO O MO

I + o o o o o NNIO N NH
I + o o o o + H Om

I o + o o o o H 2O OH

.x:: mEHu

I o o I OH00 + o o o N

I o o o o o o MMIH H MO OH
OMM OOOMO .zMIHOZO MzHO OOOZOOH OzHM :OM OMzonom oo .M.O O .OM xMO O .OM

AUOGOUV HOHUGOU "WDOMU

 

MMOHmHm MUZ¢ZUMMM

 

202

O o o o o o o OOIHH O MO

HO o o o o o o OOIN O M
I o o o o o o OOI N Om ON
I o o o o o o OOIN H 2

OH o o o o o o OOIO O OO

H o o o o o o ONIN O MO

NO 0 o o o o o ONI N am ON
I o o o o o o ONIO H M

OO o o o o o o OOIO O z

NN o o o + o o OOIO O M

OH o o o o o o OOIO N MO ON
I o o o o o o NOIO H M

OH o o o o o o OOIO N MO
I o o o o o o NOIH H z NN
I o o o o o o HNI O z
I o o o o o o OOI O M

O o o o o o o OOI N MO HN
I o o o o o o NOI H z

 

UMH MMMHO .ZMIHHZ< MZHH meZHHH MEHH DAM mmzozmom oo .Q.m O .OM Nmm O .HM

Hu.aouO Houuaoo ”MDOMO

 

MMOHOHM MUZ<ZUMMM

203

 

 

I O + o o o O OOIO H SO HM
ON O o o o o O MMIO N M

I O o o o o O NOIO H OZIZ OM
OH O O O O o o OOIO O M

M O o o O O o NOIO M MO

O O o O O o O HOIO N MO ON
I O O o O O O OOIO H M

MN 0 O O O + + OOIHH M SO

O O o O o + O OOIM N M ON
I o o O o O O NOIOH H 2

MO 0 o O O o + ONIN M zO

MN O o O o o + MNIN N M NN
I O O O O O + ONIO H M

O O o O O o O ONIM O MO

OM o O O o O O ONIN M z

OM O o O O O O MNI N am ON
I O o O O O o ONIM H z

OMH MMMHO .ZMIHHZ< MSHH OOMZHHH MZHH DHM mmzozmom uo .m.m O .QM me O .HM

Au.couV Houudou "MDOMU

 

MMOHmHE WUZ<ZGMMM

204

 

 

OO + O O O o O HOIO N MO
I + O O O O O OOIO H 2 NM
ON 0 O O O O + OOIN N I
I O O O O O + NNIM H 2O OM
MH O O O O O O ONIHH N MO
I O O O O O + ONIHH H M MM
O + O O O O O OOINH O M
O + O O O O O MOIN O SO
MH + O O O O O NOI M an MM
I + O O O O O HOINH N M
I + O O O O O OOIN H M
I + O O O O O ONIM H zO MM
MN O O O O O O NNIM M M
OH O O O O O O OOIN N 2 NM
I O O O O O + NOIO H zO
OMH MMMHO .SMIHHZ< mzHH OOMZHHH mzHH DHM mmzozmom UO .Q.m O .UM NMO O .HM
Au.aoov Houuaou ”MDOMU

 

NMOHmHm WUZ<ZUMMM

 

205

OH O + O o O o OOIOH M S
HH O + O O O O NOINH N MO NO
I O + O O O O OOIOH H M
OOH + + O O O o OOIM M MO
ON O + O O o O OOIO N M HO
I O O O O O o HMIN H M
I O O O o O o O Om
I O O O O O O M pm
OO O o O O O O OOIHH N MO OO
I O O O o O O H pm
ON O O O O O o M SO
ON O O O o O O N M OM
I O O O O O O H M
NH O O O O O o OOI N am
HO O O O O O O MOIm O SO
NH O O O O O O OOIM m S
O O O O o O O NMIH O M OM
NH O O O O O o OmIH M M
NH O O O O O O OOIO N M
I O O O o O o NOI H am

 

UMH MMDHO .SMIHHZ¢ MSHH mmMZAAH MSHB DAM mMZOSMom Uo .D.m O .UM me O .HM

Au.couV Houucoo "MDOMO

 

MOOMOHO_O97«OOMMM

206

 

 

m O O O O O O OOIO N 2O
OO o O O O O O MOIN O pm
ON + O O O O O OOIOH m z
N O O O O O O OMIm O 2 OO
NH O O O o O O NnIH m 2O
Hm O O O O O O mmIO N z
I O O O O o O HmINH H M
OO O + O O O O MMINH M M
mO O O O O O O NOIm N 2O mO
I O O O O O O NOIHH H 2
NH o + O O O O OOIm N z
I O + O O O O Oan H MO OO
I O o O O O O wan H MO mO
m + O .mxs OH + O O O OOIO m 2O
ON O O O O O + mnIm N am OO
I O O O O O O NNINH H M
NH O + O O O O HOIO O z
N O + o o O o omIm m MO
NN O + O O O O OMIO N M MO
I O + O O O O omIN H M
OMH Mmmeo .ZMIHHZ< MZHH mmMZHHH MZHH OHM mmzozmom OO .O.M O .OM NMm O .HM
Au.a00v Houuaou "MDOMO

 

MmOMmHm Muz<zomg

207

 

.xas

 

I + O O waHu + O O mnINH H 2O cm
I O O O O O O ONIM H zO mm
OM O O O O O O mOIN N M
I O + O O O O NOIO H SO Om
mNH O O O O O O ONIN O MO
ON O O O O O O HOIHH m M
MH O O O O O O mmIO N M mm
I O O O O O O NmIO H M
I O O O O O O mnIM H MO Nm
NH O + O O O O mnIm m 2
OO O + o O O O OnIHH N 2O Hm
I o + O O O O HnIH H z
Nm O O O O O O ONIN N z
I O O O .a m + O O HNIH H MO cm
I O O O O + O H MO OO
OMH mmmeo .ZMIHHZ< MZHH mmmZHHH mZHH OHM mmzozmom oo .Q.m O .UM Nmm O .HM
Au.couV Houucoo ”Maomo

 

NMOHMHM VUZ¢ZUMMM

 

208

NH O O O O O O OOIHH M 2O

amounu

m + o amuum + o o + NNIO N M an
I O O O O O O mnINH H M

OM O O O O O O OOIM M MO
OH O O O O O O OOIO O M
O O O O O O O MOIO M 2O OM
O O O O O O O NOIO N z

I O O O O O O HOIO H 2

OH O O O O O O OnlO N z

I O O O O O O OnlM H SO MM

 

UMH OMMHO .ZMIHHZ< MZHH OOMZHHH MZHH DAM mmzozmom UO .Q.m O .UM NMO O .HM

Au.coov Houucou ”MDOOO

 

NMOHmHmrwuz<ZOMMM

APPENDIX C

BACKGROUND INFORMATION

209

KEY TO ABBREVIATIONS AND SYMBOLS
USED IN APPENDICES OF BACKGROUND DATA

Abbreviations:

GYN Problems = gynecological problems

Symbols:

# = number

0 = degree relative
0 = negative history
+ = positive history

not available or

unknown

210

 

 

xHB oHOG< aomeIoHOa< I +< O NH
cmHHMuH :mHHMuH I I O HH

amaumu xHE OHOc< +m +¢ O OH

cmaumu I anHoM cmaumu +< IO< O O
:mHchm nmfiHwam +< +0 0 m

amaumo anchm I nuamuM +m +m o N

anuH SmHHoM +O +O O O

cmHamO .Omcmo I amaumu I +4 O m

cmHHmuH xHa oHOc4 IO< +< O O

sauna sauna I I O M

sauna
:mHMH I :mHHmuH I anmz I anuH I IO O N
:mHchm I nmfiamo gmHHmam I nmfivmzm I I o H
HOZOMH<M H<ZOMH¢Z H<ZOMH<M H<ZMMH<X OZMHMOMM zww O .HM

ZHOHOO UHZMHM OMMNH GOOHm

muma unmanagz I uaomuona “MOomu

 

onHOOOOMzH OzOOmOMOOO

211

 

mOoHumO

 

amoaxmz comeIoHOa< +O I< ustwmuuH + OH
coxmmIOHOc< coxmmIoHOc< +0 +0 O NH
:chNuma<: :cmoHuma<: +0 +< O OH
xm>oHO :mHumOcsm IO I< O OH
smHm3 comeIoHOG< +0 +0 O OH
anHwam cmEumO I andem I I O OH
OmaHmcm
I sauna I cmauwu .Omsuoz I nocmuM O +< O NH
cmaumo cmaumo 0 +0 O HH
:cmowuma<: :cmoHuma<: +< +< O OH
:cmoHumaO: :cmoHuma<: I I O O
comeIOHOa< comeIona< IO +O O O
cmOOaHIona< OocmuM I OmfiHwam +< +< o N
cchmsnuHH
smHuH I anHH +< +< O O
comeIOHOc< comeIoHOG< I I O m
smHHoM I :mHHmuH coxmmIOHOc< +< I< O O
I I I +O< O O
cmaumouo cmHumouO I I O N
I I I +O O H
H<ZOMH<M A¢zmmw<z H<ZOMH<M H<zmma<z OEMHOOOM zwo .HM
zHOHOO OHzmHm OOMVH OOOHO
mama .O.D I UHumuonH ”MDOMO

 

onHOzmoMzH OzOONOMOOO

212

 

Omfiwmsm

 

I cmaumo I OwHuH I0 I o NH
nocmgm I OmHchm OmOHom I I o OH
I I I I I NH
cowaIoHOS4 Sousa I I O OH
. OmHuH
Inouaa I OmOHwam Omfiacfim Io +o o MH
Ochmn OmficaOM IO +O o OH
anuH OmHHom +o +m o mH
OmOHmcm OmHchm I m o NH
nmfluH I cmaumu cmEumu I +0 I HH
cmaumo cmaumo I SmHHoM m< +O O OH
cmEumu
IOmHHH I Omfiuuoum nmfipH I OusmuM +O +m + a
sauna sauna IO IO 0 m
I amaumo I I O N
chHumE< chHuw8< +0 +0 0 O
I I +mO +0 0 m
GmEHmO .SUONO II +4 0 O
anHOM OmHHom +O IO 0 m
pagan
Icmfiuuoum I xmmuo OmHHom IO Im + N
OmOHmcm I OmHOmsm xfia oncO +O +O I H
OOzmmMOM OOzmmMOz OOzmmMON gOzmmMOz mzmqmomm zwo .MM
zHono onmam mmmwe nooqm
mumn cmONnowz I H«OBSH "MDOOO

 

onNOzmomzH azaomumoOm

213

 

 

OmfiHmam OmHHwam I I 0 mm
anuHuO
I amaumw cmauwu I :mHHoM +4 +4 O NM
I cmaumo I anHOGM 0 +4 0 OM
amoHumE4 cmoHuma4 I I 0 mM
:mHum
OmHHom Iwasm I amagmo +o IO 0 ON
GMHHmuH GMHHmuH I I 0 MM
SmHHOcm xHa oHOc4 +4 +0 O NM
augumo OmHHwam +o +mO O HM
anuH I cmHOGH
I nucwHM xm>0HO m 0 0 OM
cmfimem I sauna sauna I cmeHmm +O +0 0 ON
:oamuM I anuH xHa oHOc4 I +0 0 ON
sauna I nuamuM cmaumu I nocmuM +0 +4 0 NN
amaumo I OmHuH :mHuuoum Im +o O ON
smHHOcm I cmaumo coxmmIoHOa4 0 4 0 ON
nocqu Sousa I4 I0 0 ON
OmHHoM mmmuHmz I I O MN
cmaumu I anHOM xHE onc4 +4 +0 0 NN
noamuM
IamEHmO I anHOM amaumo I socmuM +4 +4 0 HN
amaumu cmaumu +4 +O O ON
H4zmmH4M H4zmmH4Z H4ZOMH4M H4ZOMH42 OEMHOOOM zwu O .HM
zHOHOO OHzmHm OOMOH OOOHO
Au.coov mama cmOHsoHE I umOEDH "MDOOO

 

232523 OZOOOOMOOM

214

 

 

OmHHmam mmfizm I nmfiuuoom +O +m + om
cmaumw cmEHmO I nuamuM +O +4 I OO
OmHHom I amaumu xfla onaO +mO +o o OO
amHuum=4
I Smfiaom fimfiHH +m +m O NO
deumo I gmHHOGM xHE oHOa4 +0 +0 0 OO
anuuooO :mHuH +m +0 0 OO
cmEumO :maumo I 0 O OO
cmaumo
I anOmsm
I OmHHmam coxmmIonaO +m +0 0 mO
amaumo deHmuH +0 +O O NO
cmHHmuH cashmo I :mHuH m +4 0 HO
nocmuM
coxmmIOHOC4 IanuH I :mHOcH +0 +0 0 OO
casumo
anHOM IsocmuM I smHHOcM +4 IO 0 OM
H4ZMMH4M H4ZMMH4E H4ZMMH4M H4ZMMH4Z OZMHOOMM ZWU O .HM

ZHOHMO UHZMHM OMMVH DOOHm

Hu.aou0 mumo ammHOUHz I “Open; ”Macao

 

onNOOMONzH azaomOMOOm

215

 

 

:mHHwam :mHHmam I cmauoo I I0 O ON
cmaumo cmaumo I +0 0 OH
OHDA

fimHuH I LmHamOO ImeDH I cmaumu I I O OH
I I I +4 0 NH

Sousa LmHHoM I cmaumu +0 IO4 O OH

anuuoum
anuH I :mHOGH .umE4 +0 +0 0 MH
cmHuu

Ims4 I amaumu amaumu I :mHHOcm +0 +0 0 OH
GmEumu aoxmmIoHOC4 +0 +0 0 OH
cmaumo I OmHuH :mHamuxO O +m4 O NH
xHB oHO:4 sauna I4 +0 + HH
xwmuo anuH +O4 +0 0 OH

casumu cwaumu I :mHHH + I O O

Sousa I cmaumu Sousa I cmEumo I +O O O
anHOCM OmHHOcM I amaumo +0 +4 0 N
:mHHwam I sauna nmfiufium IO +O O O
I I +0 I4 0 m

I I +0 IO4 O O

cmEumu amaumo +O4 +4 0 M
cmmaounm .3.z cmmmonsm .3.z I I O N
:mHHmuH smHHOM I I O H

H4ZOMH4M H4zmm94z H4ZMMH4M H4zmme4z OEMHOOMM ZOO .HM
zHoHOO OHZMHM OMMMH OOQHO
"MDOOU

 

282533 OZOOOOOOOM

216

 

 

comeIoHOc4 aonOIoHOc4 0 +O4 0 MO
I I I I O NO
:mEumu coxmmIoHOc4 +4 +4 0 HO
I I I I + OO
I I +0 +0 0 OM
I I I I O OM
I I +0 +m4 0 NM
:mEumO I anHOcm amHOGH I zmHuH 4 +4 0 OM
I I I I 0 MM
casumo I OmHHom OmHHOam I Ooamum +o +O + ON
I I I I0 0 MM
I I IO I4 0 NM
I I +4 +0 0 HO
I I I I O OM
OmHHwam comeIoHOa4 I +0 0 ON
NHE ona4 NHB oHOa4 I4 +0 0 ON
I I I +0 0 NN
cmHOnH I Locqu :chmO I cmaumo +4 +0 0 ON
I I I I 0 ON
I I +O +0 0 ON
GOOHumE4 GOUHHOE4 +0 I + MN
anuH I :OEHOO sousn I :mHHwam +O +O + NN
cwaumo I anHOGM zmHHOGM I amaumu +0 +O 0 HN
H4ZOMH4M q4zmme4z H42MOH4M H4zmmw4z OZMHOOOM zwo O .HM
zHOHOO OHzmHM OMMWH OOOHO
Au.aouO muma .m.: I umnasH "MDOOO

 

ZOHHSEOMZH OZDOOOM04O

217

 

 

amEumu I cmHOHmO comeIOHOG4 I I 0 On
cashmo :mHOw3O I cmaumu +0 +0 0 mm
amHHmuH

I anHOcm cmfiumo I :mHHOcm I4 I4 0 NM
cmoHum84 amoHumE4 I +4 O HO

socqu I cmaumu oHO:4 I cmauwu +O +O 0 0m
OmHHOGM I cmsumu aonOIoHOc4 I I I OO
:meumo I :mHHOam cmEumu I :mHnH +O +O O OO
cmaumu NHE ona4 +0 +0 0 NO

cmaumc LwHHOcm +O I + OO

GOUHqu4 amoHnw84 I0 I4 0 OO

xHE OHOG4 .cuwmu I noamuM +4 I0 0 OO
H4zmmH4M H4zmme4z H4ZOMH4M H4zmme4z OXMHOOOM ZOO O .HM

zHOHOO OHZMHM OOMOH OOOHO
Au.aouO mumm .0.0 I umnEDH uMDOOO

 

zOHHOmeMzMIOZOOOOMOg

218

 

OmHHOam I cmaumu OmHHmam I amaumo +O +O O N

 

anOmam >mHmoO=O
I :mHuH I cmEumo I I O O
OHS oHOc4 cmEumu I anHom +O IO 0 M
anmmsm
cocmuM I oHO:4 Ismaumo I :mHHom +O +4 + O
amHOaH
I nucmuM amHOaH
I amHOmaqu IanHOcm I nucmuM 4 I O M
I cmHOaH I nocmuM I I O N
OmOHwam nmfiHwam I I O H
H4ZOOO4M H4ZOMH4Z H4ZOMO4M H4ZOOO4Z OZOHOOOM ZOO O .OM
ZHOHOO OHZMOO OOMOO O00HO

mama chHnon I kuomm ”MDOOU

 

ZOHH<Z&OMZH QZDomomodm

219

 

 

OmHHOcO :mHuuooO I anuH O4 +O O OH
oHOc4 I amaumu amHOm3uoz I I O OH
amHHmuH
I .OOONO Omfiamam +m +O O OH
:mNHom amonmz +0 I4 O NH
coaqu I zmHuH anHom I :mHuH +0 I 0 HH
xHE oHOa4 cmEumo I :mHamO +0 +0 + OH
:cmowuma4: ::MUHumE4: +0 +4 0 O
amonwz :amoHqu4: +4 +O4 + O
I +4 0 N
OmHHOOO ammaousm .z +O +O O O
unaumu :mBqu 0 0 O O
cmsumu :mHuH I cmaumO O O O O
:omeIoHOc4 coxmmIoHOc4 +0 +O 0 m
cmaumu cause I amEumO +O +4 0 N
:cmowum84: :amoHuma4: I I O H
A4ZOOO4O O4ZOOH4Z O4ZOOO4M O4ZOOO4Z szHOOOM ZOO O .OO
ZHOHOO OHZOOO OOOOO OOOOO
.0.0 I Hmuomm "OOOOO

 

ZOHH<ZMOMZHIQZDOO0M04O

220

 

 

comeIOch4 anuH I noamuM +O +4 + HH
:mHumOaam
:mHHom I cmsumw I OmfiuH I I + OH
COUHNmB4 GOUHHm84 I4 IO4 O O
:mHHom OmHHH I amfiuwu
I cmfiHmuH I cmficmanusq +O +O O O
amaumu
I OOOHOOH xfia onaO +O +O O N
I I +O4 +4 0 O
sauna st OHOOO +O IO + m
sauna sauna +O +4 + O
cmaHmuH sauna
I ancaHM ILOHHH I anacHM +O +0 0 m
:mHOOBO
I :MEHQO nmficcHM I +O O N
cmEumw :wHHoM I amaumu I4 +4 0 H
O4ZOOO4M O4ZOOH42 O4ZOOH4O O4ZOOO4Z OzOOOOOM ZOO O .OM
ZHOHOO OHZOOO OOMOO Ooqu
. mumO ammfinofiz I “mayo "OOOOO

 

ZOHH4ZOOMZH QZDOMUMU4O

221

 

 

xHE oHO:4 xHE oHOc4 I +0 0 O
Ouuao
:oxmmIonaO IOmHuH I :mOOaH +O IOO O m
amoHuma4 GOUHHOE4 +0 +4 + N
:mHHOaO
:mHHOCO I :mEumO I :mHOmam +0 IO4 O H
OOZOOH4O O4ZOOH4Z A4ZOOO4M H4ZOOH4Z OZOOOOOM ZOO O .OO

ZHUHOO UHZEHM

OOMOO OOOHO

wuma .0.0 I Hmsuo "OOOOO

 

ZOHH<ZOOMZH DZDOMQM04O

222

 

 

ONE oHOa4 conOIoHOG4 +0 +0 0 N

cmEuwo I :mwwm3m comeIoHOc4 +O4 +0 0 O

xfis OHOOO xfis oncO +O +O + m

cmaumu ONE oHOc4 I +4 + O

xHE oHO:4 xHE oHOc4 I +0 + m

sucmuM xm>0HO +4 +0 O N

comeIOHOc4 comeIoHOc4 +0 +4 0 H
O4ZOOO4O O4ZOOO4Z O4ZOOO4O O4ZOOO4Z OZOOOOOM ZOO O .OO

ZHOHOO OHZOHO OOOOO nooHO

mama cmOHaowz I OHOUOHmsmmucm "ODOOO

 

ZOHH4SOOMZH.QZDOO0M04O

223

 

 

OmfiHom anHoM I nocmuM I I 0 MN
amHHmOH I I I + NN
cmaumo I OmHHOcO xHa oHOa4 +0 +0 0 HN
anHom SOHmmsm I +O 0 ON
cmfiHmuH cmaumO +4 +4 0 OH
sauna sauna I amBumu I +0 + OH
cmHHmuH OONHH + +4 0 NH
cmaumu sauna I +4 + OH
+4 +4 0 OH
+0 +0 0 OH
+4 +4 0 OH
+O +0 0 NH
+ +4 0 HH
amHHmuH I cmeumo cmHmmam +4 +0 0 OH
I +0 0 O
+O4 +4 0 O
I I 0 N
+0 “0 O
+ I O O
I I O O
I0 I0 0 O
I I O N
+O +O + H
O4ZOOH4O O4ZOOH4Z O4ZOOH4O O4ZOOO4Z OSOHOOOO ZOO O .HO
ZHOHOO OHZOHO OOOOH OOOHO

Houuaou “MDOOU

 

ZOHH<ZMOM2H QZDOOUMU4O

224

 

 

Sousa I I I 0 OO
:oxmmIoHOc4 :mHHOcO I I 0 NO
sauna nouan +0 +O4 O HO
I I I +4 0 OO
I I O O I OM
OHS oHOc4 aoxmmloHOc4 I + O OM
cowaIoHOc4 :omeIoHOc4 0 4 O NO
I I + + I OM
Sousa cmuauma4 I0 +0 O OO
I I I I + OM
cmanww socmuM +O IO 0 OO
GOOHHOE4 :mofium84 0 0 0 NM
OmOHOam I sauna cause I ameumo +O +O O HO
OmHuuoum
I LucmuM cmaumu I sauna I I + OM
OmHuH OmOHom I +O O ON
smHHom cwHHmuH I 4 O ON
ONE oHOc4 :OEHOO I0 +4 0 NN
cmOHumE4 Sousa +0 +0 0 ON
cmaumo cmHumwcsm I I 0 ON
cchmsnuHH
cmBumO I amaumu +4 +4 0 ON
H4ZOOO4O O4ZOOH4S H4ZOOO4O A4ZOOO4$ OZOHOOOO ZOO O .OO
ZHOHOO OHZOOO OOOOH OOOHO
Au.coov Houucou “ODOOO

 

ZOHH42MOMZH QZDOMUMU<O

225

 

 

nmfluH I amauou nouns +o +< o ,mn
Sousa sauna + + + Om
I I I I 0 um
I I I +0 0 mm
sauna sauna I +4 0 Om
nmfiamcm cmaumu Io Io o mm
sauna sauna IO4 +0 0 NM
sauna I amaumo Sousa I +4 0 an
cmEumO amauwo +4 I4 0 Om
amaumu :mHHH +O4 I + OO
sauna amfiwsH I nmfiawcm +o +m< o wO
Sousa amaumu I zmwvm3m IO +4 + BO
nousm I smHHom smfiwmam I Ouamum O O O OO
chHuma4 cmowume4 I I 0 MO
cmaumo I cmfiuums4 nmficafim I cmaumo +4 +0 0 OO
O4ZOOH4O O4ZOOH4X O4ZOOH4O O4ZOOH42 mEOOOOOm 2M0 .HO
ZHOHOO OHZOHO mOOwH O004O
Au.coov Houucoo "ODOOO

 

ZOHH4ZOOOZH.QZDOOOM04O

APPENDIX D

QUESTIONNAIRE

 

ummwnsau
no uoomnnau

 

uummmv no mmmmmfiv
uummn Hauwamwaou

 

wafiam msu mo mu5u
Im>u50v mwmoqaoum

 

226

Amwaasww no mummo

mvaaoawv Ocfix haw
mo mamanoum MUMO

 

msamnmmuouwhm

 

 

 

 

 

mHmuoamsmwucm
no .mamnawucmam

.mwfimfin mafigm

 

 

muwwuu ouoaz uwmco um mw4 mumwnuuHO manmcoaumawu wcm wamz

mmH<zonemmao

aoguficaou

wOOHmHm NAHZ4O

227

 

knoumfin Hmuavwa
haaamm ucm0fim
Iaawwm uwzuo ma4

 

maouwchm m.a300

 

Acaoax OH .mmsmu
muoav :uuHOHHHum

 

mmoa

mnu mo mega man
um macaw HMO Bo:
muoav coauuonm
no mwmwuumomaz

 

Anamocmum uauoahm
..m.mv muummmw
acumhm m>HumwwHO

 

 

 

 

muaamm\afia ummao

 

 

 

Omummuu mumnS

ummco um mw4

mumvnuuHO NflnmaoaumHmH Ocm mamz doauwvaoo

A.u.aou0 wmoamHm OAHZOm

mmH<zonHmmoo

228
QUESTIONNAIRE

PREGNANCY HISTORY AND BACKGROUND INFORMATION

1. What is the ethnic origin of the affected person's
mother? father?

 

 

2. What are the parents' blood types? Mother Father

3. Was the mother of the affected child exposed to any
of the following environmental agents before or during
the pregnancy that resulted in the birth of the child
with spina bifida? At which point in the pregnancy or
how long before conception?

(check one)
agent yes no when?

 

birth control pills

 

fertility drugs
(e.g., clomid)

 

hormones (any
kind)

 

flu

 

any viral ill-
ness

 

anti-morning sick-
ness medication

 

any other medication

 

 

 

 

 

If the mother was exposed to any of the above-mentioned
agents during other pregnancies, please note that in the
space below.

4. How long did it take for the parents to conceive?

5. Has the mother had any gynecological problems for
which she has had to seek treatment?

6. Have either parent had back X—rays? What
were the results of those X-rays?

229

QUESTIONNAIRE

TOTAL NUMBER OF FAMILY MEMBERS

Total number of children (brothers and sisters of
the child with spina bifida

 

List below:

Birthdate Sex

For each side of the family, please list the number of
blood relatives in each category.

Relative Mother's side Father's side

 

Brothers

 

Sisters

 

Nieces

 

Nephews

 

Aunts

 

Uncles

 

 

 

 

Comments:

Mother's birthdate

 

Father's birthdate

 

230
QUESTIONNAIRE

This page is to provide information on your child's spina
bifida. In order for this study to be informative, I need
to know where the level of the spina bifida is )e.g., T-9
to T-12, T-lO through the sacrum, occipital encephalocele,
etc.).

What is the level of your child's (or the affected
person's) spina bifida?

 

What is the extent of involvement of the spina bifida?
(E.g., does it include all of the lumbar spine and sacral
spine if it is an L-2 level, or does it just include

L-2 and L-3?)

If you do not know the level or extent of involvement,
describe as best as you can where the spina bifida is
located on the back, and what functions of the child
are affected (e.g., does he/she have bowel or bladder
control? Can he/she walk with braces? Can he/she walk
at all?) Whatever information you can provide would
be useful.

231
QUESTIONNAIRE

STATEMENT OF CONSENT

I heretofore agree to provide Helga Toriello and
the Michigan State University Genetics Clinic with all
pertinent medical records and my family history for
the study entitled "Investigation of Heterogeneity
Among Neural Tube Defects". I understand that there
are no benefits to me, but that the results could be
of use to medical science in the genetic counseling
of other families. I also understand that all infor-
mation gathered will be completely confidential, and
that if published, all persons will remain anonymous.
I am aware of the fact that I can withdraw from the
study at any time, and all information gathered on
my family will be accessible to me or my family
physician, if we so desire.

Signature of participants

 

 

 

(parents of child and child if over the age of seven)

BIBLIOGRAPHY

BIBLIOGRAPHY

1. Tuchmann-Duplesis, H., Auroux, M., and Haegel, P.
Illustrated Human Embryology Vol. III, Nervous System and
Endocrine Glands, pp. 1-29, 84-86. Springer-Verlag, N.Y.,
1974.

 

 

 

2. Linville, G.P., and Shepard, T.H. Neural tube closure
defects caused by cytochalasin B. Nature New Biol. 236:
246-8, 1972.

3. Anderson, F. Occult Spinal Dysraphism: A series of 73
cases. "Pediatrics" SS: 826—834, 1975.

4. Parke, W.W. "Development of the Spine" in The Spine
Vol. 1 ed. Rothman, R.H. and Simeone, F.A. W.B. Saunders
Co. 1975, Philadelphia, pp. 1—12.

 

5. Simpson, D. Congenital malformations of the nervous
system. Med. J. Aust. 1: 700-2, 1976.

6. Alter, M. Anencephalus, hydrocephalus, and spina bifida.
Arch. Neurol. and Psychiat. 7: 411, 1962.

7. Epstein, 8.8. The Spine. Lea and Lebiger, Phila., 1953.

 

8. Matson, D.D. Neurosurgery of Infancy and Childhood.
Chas. Thomas, Springfield, 111., 1969.

 

9. Harris, H.W.,and Miller, O.F. Midline cutaneous and
spinal defects. Arch. Dermatol. 112: 1724-28, 1976.

10. Recklinghausen, F. Untersuchungen fiber die spina bifida
Virchows. Arch. Path. Anat. 105: 243, 1886.

11. Gardner, W.J. The Dysraphic States, 1973. Elsevier.

 

12. Patten, B.M. Overgrowth of neural tube in young human
embryos. Anat. Rec. 113: 381-393, 1952.

13. Vogel, F.S.,and McClennahan, J.L. Anomalies of major
cerebral arteries associated with congenital malformations
of the brain; with specific reference to the pathogenesis of
anencephaly. Am J. Path. 28: 701, 1952.

232

233

14. Caviness, V.S.,and Evarard, P. Occipital Encephalo-
cele: A Pathologic and anatomic analysis. Acta Neuro-
pathol. (Ber1.) 32: 245-55, 1975.

15. Leong, A.S.Y.,and Shaw, C.M. The Pathology of occipi-
tal encephalocele and a discussion of the pathogenesis.
Pathology 11: 223-34, 1979.

16. Gardner, W.J. Myelomeningocele, the result of rupture
of the embryonic neural tube, Cleveland Clin. Quart. 27:
88, 1960.

17. Kalter, H.,and Warkany, J. Experimental production of
congenital malformations in strains of inbred mice by mater-
nal treatment with hypervitaminosis A. Amer. J. Pathol.

38: 1-14, 1961.

18. Marin-Padilla, M., and Lerm, V.H. Somite necrosis and
developmental malformations induced by vitamin A in the
golden hamster. J. embryol. exp. Morph. 13: 1—8, 1965.

19. McCredie, J. Embryonic Neuropathy: A Hypothesis of
neural crest injury as the pathogenesis of congenital mal-
formations. Med. J. Australia 1: 159-63, 1974. (Feb. 9)

20. Sever, L.E. Letter: Pathogenesis of congenital mal-
formations. Med. J. Aust. 2: 178, 1974.

21. David, T.J., and Nixon, A. Congenital malformations
associated w/anencephaly and iniencephaly. J. Med. Genet.
13: 263-5, 1976.

22. Lorber, J., and Schofield, J.K. The Prognosis of occi—
pital encephalocele. Z. Kinderchir 28: 346—51, 1979.

23. Lichtenstein, B.W. Distant neuroanatomic complica-
tions of spina bifida (spinal dysraphism); hydrocephaly,
Arnold-Chiari deformity, stenosis of aqueduct of Sylvius,
etc.; pathogenesis and pathology. Arch. Neurol. and
Psychiatr. 47: 195-214, 1942.

24. Barry, A., Patten, B.M., and Stewart, B.H. Possible
factors in the development of the Arnold-Chiari malforma-
tion. J. Neurosurg. 14: 285-301, 1957.

25. Duckett, S. Fetal Arnold-Chiari malformation. Acta
Neuropath. 7: 175-

26. McLennan, J.E. Rib anomalies in myelodysplasia. An
approach to embryologic inference. Biol. Neonate 29:
129-41, 1976.

234

27. VanWent, J.J., VanWent, G.P., Delleman, J.W., and
Becker, A.C. Spina bifida and so-called asplenia syndrome
occurring separately in sib. Teratology 15: 195-8, 1977.

28. Carter, C.0., and Evans, K.A. Spina bifida and anen-
cephalus in greater London. J. Med. Genet. 10: 209-34,
1973.

29. Anderson, A.B.M., Pierepoint, C.G., Griffiths, K., and
Turnbull, A.C. Steroid metabolism in the adrenals of fetal
sheep in relation to natural and corticotrophin induced par-
turition. J. of Reprod. and Fertil. 16 (suppl.): 25-38,
1972.

30. Elwood, J.H. and Nevin, N.C. Factors associated with
anencephalus and spina bifida in Belfast. Br. J. Prev. Soc.
Med. 27: 73-80, 1973.

31. Williamson, B.M. Incidence and family aggregation of
major congenital malformations of the central nervous system.
J. Med. Genet. 2: 161-72, 1965.

32. Silberg, S.L., Watson, F.R., and Martin, J.C. Seasonal
variation of congenital malformations. Can. J. publ. Hlth.
59: 239-43, 1968.

33. Czeizel, A. and Revesz, C. Malformations of the CNS.
Br. J. Prev. Soc. Med 24: 205-222, 1970.

34. Laurence, K.M. Spina bifida research in Wales. J. R.
Coll. Physicians Lond. 10: 333-46, 1976.

35. Singer, H.A., Nelson, M.M., Beighton, P.H. Spina bifida
and anencephaly in the Cape. S. A. Med. J. 53: 626-7, 1978.

36. Odeku, E.L., Grant, I.H., Ekop, A.C. Congenital mal-
formations of the cerebrospinal axis seen in W. Nigeria.
The Spinal Meningoceles. Int. Surg. 47: 580-95, 1962.

37. Biggar, R.J., Mortimer, E.A, and Haughie. Descriptive

epidemiology of neural tube defects, Rochester, N.Y. 1918-
38. Am. J. Epidem. 104: 22-7 , 1976.

38. Naggan, L. Anencephaly and spina bifida in Israel.
Pediatrics 47: 577-86, 1971.

39. Wynne-Davies, R. Congenital vertebral anomalies; aeti-
ology and relationship to SBC. J. of Med. Genet. 12:
280-8, 1975.

40. Sandahl, B. Seasonal incidence of some congenital mal-
formations in the CNS in Sweden, 1965-1972. Acta Paediatr.
Scand. 66: 65-72.

41. Elwood, J.M. Seasonal variation in anencephalus in
Canada. Brit. J. Prev. Med. 29: 22-26, 1975.

42. Naggan, L., MacMahan, B. Ethnic Differences in the

prevalence of anencephaly and spina bifida in Boston, Mass-
achusetts. NEJM 277: 1119-1123, 1967.

43. Carter, C.0., David, P.A., and Laurence, K.M. A Family
study of major CNS malformations in S. Wales. J. Med.
Genet. 5: 81-106, 1968.

44. Leck, J. Causation of Neural Tube Defects: Clues from
epidemiology. Br. Med. Bull. 32: 158-63, 1974.

45. Fedrick, J. Anencephalus in Scotland 1961-72. Brit. J.
Prev. Soc. Med. 30: 132-37, 1976.

46. Elwood, J.M., Raman, S., and Mousseau, G. Reproductive
history in the mothers of anencephalics. J. Chron. Dis. 31:
473-81, 1978.

47. Kurent, J. and Sever, J.L. Perinatal infections and
epidemiology of anencephaly and spina bifida. Teratology
8: 359-62, 1974.

48. Warkany, J. Congenital Malformations: Notes and Com-
ments. Chicago: Year Book Medical Publishers, Inc., 1971.

 

49. Suwanwela, C. and Hongsaprabohas, C. Frontoethmoidal
Encephalomeningocele. J. of Neurosurg. 25: 172-182, 1966.

50. Carter, C.0. Spina Bifida and Anencephaly: A Problem
in genetic-environment interaction. J. Biosoc. Sci. 1:
171-83, 1969.

51. Elwood, J.M. and Mousseau, G. Geographical, secular
and ethnic influences in anencephalus. J. Chron. Dis. 31:
483-91, 1978.

52. Birth Defects Monitoring Program, 1960-1979. Personal
Communication.

53. Janerich, D.T. and Piper, J. Shifting genetic patterns
in anencephaly and spina bifida. J. Med. Genet. 15: 101-
05, 1978. 1

236

54. Schwidde, J.T. Spina Bifida: Survery of two hundred 25
encephaloceles, meningoceles, and myelomeningoceles. Am. J.
Dis. Child. 84: 35-51, 1952.

55. Alter, M. Anencephalic births in a northern and south-
ern community. Am. J. Dis. Child. 106: 536-44, 1963.

56. Yen, S., MacMahon, B. Genetics of anencephaly and
spina bifida? Lancet 2: 623-26, 1968.

57. Horowitz, J., McDonald, A.D. Anencephaly and spina bi-
fida in the Province of Quebec. Can. Med. Assoc. J. 180:
746-55, 1969.

58. Lippman-Hand, A., Fraser, F.C., and Cushman-Biddle, C.J.
Indications for prenatal diagnosis in relatives of patients
with neural tube defects. OB-GYN Sl: 72-76, 1978.

59. Frezal, J., Kelley, J., Guillemot, M.L., and Lamy, M.
Anencephaly in France. Am. J. Hum. Genet. 16: 336-50,
1964.

60. Hagberg, B., Sjogren, 1., Bensch, K. The incidence of
infantile hydrocephalus in Sweden. Acta Pediatr. 32: 588-
94, 1963.

61. Stevenson, A.C., Johnston, H.A., Stewart, M.I. and
Golding, D.R. Congenital Malformations: A Report of a
study of series of consecutive births in 24 centres. Bull.
WHO (suppl. to Vol. 34) Geneva.

62. Odeku, E.L. Congenital malformation of the cerebro-
spinal axis seen in W. Nigeria. The African child with en-
cephalocele. Internat. Surg. 48: 52-62, 1967.

63. Verma, 1.0. High frequency of neural tube defects in
North India. Lancet 1: 879-80, 1978.

64. Neel, J.V. A Study of major congenital defects in
Japanese infants. Am. J. Hum. Genet. 10: 398-445, 1958.

65. Penrose, L.S. Familial data on 144 cases of anenceph-
aly, spina bifida, and congenital hydrocephaly. Annals of
Eugenics 13: 73-98, 1946.

66. Cowchock, S., Ainbender, E., Prescott, G., Crandall,
B., Lau, L., Heller, R., Muir, W.A., Kloza, E., Fligelson,
M., Mennute, M., and Cederquist, L. The Recurrence Risk
for Neural Tube Defects in the United States: A Collabora-
tive Study.

237

67. Richards, I.D.G., McIntosh, H.T., Sweenie, S. A
Genetic study of anencephaly and spina bifida in Glasgow.
Devel. Med. Child. Neurol. 14: 626-39, 1972.

68. Carter, C.0. and Evans, K. Children of adult survivors
with spina bidida cystica. Lancet 2: 924-6, 1973.

69. Lorber, J. The Family history of spina bifida cystica.
Pediatrics 35: 589-595, 1965.

70. Bergsma, D. Birth Defects Compendum 2nd ed. Alan R.
Liss, N.Y., 1979.

 

71. Behrman, R.E. Neonatology: Diseases of the fetus and
infant. C.V. Mosby, 1973.

 

72. Timson, J. A Study of the first degree relatives of
the parents of Spina bifida children. "Clin. Genet." 3:
99-102, 1972.

73. Edwards, J.H. Letter: Risks of malformed relatives.
Lancet 1: 1348, 1976.

74. Nevin, N.C. and Johnston, W.P. A Family study of spina
bifida and anencephalus in Belfast, Northern Ireland. J.
Med. Genet. 17: 203-11, 1980.

75. Book, J.A., and Rayner, S. A Clinical and genetical
study of Anencephalus. Am. J. Hum. Genet. 2: 61-84, 1950.

76. Record, R.G., and McKeown, T. Congenital malformations
of the central nervous system. I. Maternal reproductive
history and familial incidence. Br. J. Soc. Med. 4: 26-50,
1950.

77. Polman, A. Anencephaly, spina bifida, and hydrocephaly,
a contribution to our knowledge of the causal genesis of
congenital malformations. Genetica 25: 29-

78. Smithells, R.W., D'Arcy, E.E., and McAllister, E.F.
The Outcome of pregnancies before and after the births of
infants with nervous system malformations. Devel. Med.
Child. Neurol. Suppl. 15, 6-10, 1968.

79. Cohen, T., Stern, E., and Rosenmann, A. Sib Risk of
Neural Tube Defects: Is Prenatal diagnosis indicated in
pregnancies following the birth of a hydrocephalic child?
J. Med. Genet. 16: 14-16, 1979.

9238

80. MacMahon, B., Pugh, T.F., Ingalls, T.H. Anencephalus,
spina bifida, and hydrocephalus. Br. J. Prev. Soc. Med. 7:
211-9, 1953.

81. McDonald, A.D. Abortion in neural tube defect fraterni-
ties. Br. J. Prev. Soc. Med. 25: 220-1, 1971.

82. Creasy, M.R. and Alberman, E.D. Congenital malforma-
tions of the central nervous system in spontaneous abortions.
J. Med. Genet. 13: 9-16, 1976.

83. Evans, R. Neural Tube Defects: Importance of a history
of abortion in etiology. Br. Med. J. 1: 975-6, 1979.

84. Warburton, D., Fraser, F.C. Spontaneous Abortion Risks
in Man: Data from reproductive histories collected in a
medical genetics unit. Am. J. Hum. Genet. 16: 1-25, 1964.

85. Coffey, V.P. and Jessop, W.J.E. A Study of 137 cases
of anencephaly. Brit. J. Prev. Soc. Med. 11: 174-
1957.

86. Baker, D.A. and Sherry, C.J. Spina bifida and maternal
Rh blood type. Arch. Dis. Child. 54: 567, 1979.

87. Golding, J. and Butler, N.R. Spina bifida and maternal
Rh blood type. Arch. Dis. Child. 55: 244-

88. Collmann, R.D., Stoller, A. Relation of congenital ab-
normalities of the CNS to the blood group of the mother.
Aust. NZ J. OB—GYN 2: 38-40, 1962.

89. Wilson, T.S. A Study of congenital malformations of
the CNS among Glasgow births 1964-8. Health Bull. (dinb.)
29: 79-87, 1971.

90. McKeown, T., Record, R.G. Malformations in a population
observed for 5 years. In: Wolstenholme, G.E.W.. O'Connor,
C. Meds. CIBA foundation symposium on congenital malforma-
tions. London: Churchill, 1960.

91. Bobrow, M., Bodmer, J., Bodmer, W., McDevitt, H.0.

The Search for a human equivalent of the mouse T - locus -
negative results from a study of HL-A types in spina bifida.
Tissue Antigens SC: 234-7, 1975.

92. DeBruyere, M., Kulakowski, S., Malchaire, J., Delire,
M., and Sokal, G. HLA gene and haplotype frequencies in
spina bifida. Population and family studies. Tissue Anti-
gens 10: 399-402, 1977.

239

93. Schacter, B., Gyves, M., Muir, A., and Tasin, M.
HLA-A, B compatibility in parents of offspring with neural
tube defects or couples experiencing involuntary fetal
wastage. Lancet 1: 796-99, 1979.

94. Doll,, R., Hill, A.B., Sakula, J. Asian influenza in
pregnancy and congenital defects. Brit. J. Prev. Soc. Med.
14: 167-72, 1960.

95. Wilson, M.G. and Stein, A.M. Teratogenic effects of
Asian influenza. J.A.M.A. 210: 336-7, 1969.

96. Coffey, V.P. and Jessop, W.J.E. Maternal Influenza and
Congenital Deformities: A Follow up study. Lancet 1: 748-
751, 1963. ’

97. Kleinebrecht, J., Michaelis, H., Michaelis, J., Koller,
S. Fever in prengnacy and congenital anomalies. Lancet 1:
1403, 1979.

98. Miller, P., Smith, D.W. and Shepard, T.H. Maternal
Hyperthermia as a possible cause of anencephaly. Lancet 1:
5-19-20, 1978.

99. Chance, P.F., Smith D.W. Letter: Hyperthermia and
meningomyelocele and anencephaly. Lancet 1: 769-70, 1978.

100. Halperin, L.R. and Wilroy, R.S. Maternal hyperthermia
and neural tube defects. Lancet 2: 212-13, 1978.

101. James, W.H. Letter: Hyperthermia and meningomyelocele
and anencephaly. Lancet 1: 770, 1978.

102. Rapola, J., Saxen, L., and Granroth, G. Anencephaly
and the sauna. Lancet 1: 1162, 1978.

103. Greenberg, G., Inman, W.H.W., Weatherall, J.A.C. and
Adelstein, A.M. Letter: Hormonal pregnancy tests and con-
genital malformations. Brit. Med. J. 1: 191-2, 1975.

104. Rothman, K.J., and Louik, C. Oral contraceptives and
birth defects. New Engl. J. Med. 299: 522-24, 1978.

105. Ortiz-Perez, H.E., FuertesdelaHaba, A., Bangdiwala,
1.8., and Roure, C.A. Abnormalities among offspring of oral
and non-oral contraceptive users. Am. J. OB-GYN 134: 512-
17, 1979.

106. Kasan, P.N. and Andrews, J. Oral contraception and
congenital abnormalities. Br. J. OB-GYN 87: 545-51, 1980.

240

107. Smithells, R.W., Sheppard, S. and Schorah, C.J.
Seller, M.J., Nevin, N.C., Harris, R., Read, A.P. and
Felding, D.W. Possible prevention of neural tube defects by

periconceptual vitamin supplementation. Lancet 1: 339-40,
1980.

108. Wynn, V. Vitamins and oral contraceptive use. Lancet
1: 561, 1975.

109. Cohlan, S.Q. Congenital anomalies in the rat produced
by excessive intake of vitamin A during pregnancy. Pedia-
trics 13: 556-567, 1954.

110. Warkany, J. and Petering, H.J. Congenital malforma-
tions of the CNS in rats produced by maternal zinc defic-
iency. Teratology 5: 319-34, 1972.

111. Tfinte, W. Zur frage der jahreszeitlichen Haufigkeit
der anencephalie. Humangenetik 6: 225-36, 1968.

112. Hibbard, E.D. and Smithells, R.W. Folic acid metab-
olism and human embroypathy. Lancet 1: 1254, 1965.

113. Walker, F.A. Familial spina bifida associated with
anti-emetic ingestion in the first semester (sic). Birth
Defects 10(7): 17-21, 1974.

114. Yerushalmy, J., Milkovich, L. Evaluation of the
teratogenic effect of meclizine in man. Am. J. OB-GYN
93: 553-61, 1964.

115. Pettersson, F. Meclizine and congenital malformations.
Lancet I: 675, 1964.

116. Smithells, R.W., Chinn, E.R. Meclizine and Fetal
Malformations: A Prospective study. Brit. Med. J. 1: 217-
18, 1964.

117. Cordero, J.F., Oakley, G.P., Greenberg, F., James,
C.M. Is Bendectin a teratogen? J.A.M.A. 245(22): 2307-10.

118. Knox, E.G. Twins and neural tube defects. Br. J.
Prev. Soc. Med. 28: 73-80, 1974.

119. Rogers, S.C. Anencephalus, spina bifida, twins and
teratoma. Br. J. Prev. Soc. Med. 30: 26-8, 1976.

120. Clarke, 0., Hobson, D., McKendrick, C.M., Rogers, S.C.,
Sheppard, P.M. Spina bifida and anencephaly 'miscarriage as
possible cause'. Br. Med. J. 4: 743-6, 1975.

241

121. Arias-Bernal, L. and Jones, B.W., Jr. An Anencephalic
male with XX sex chromosome complement. Am. J. OB-GYN 99:
877-8, 1967.

122. Wiesli, B. Comparison of the phenotype and nuclear
morphological sex in 3029 newborn infants. Acta Anatomica
51: 377-83, 1962.

123. Roberts, C.J., and Lloyd, S. Area differences in spon-
tenaous abortion rates in S. Wales and their relation to
neural tube defect incidence. Brit. Med. J. 4: 20-2, 1973.

124. Elwood, J.H. Aetiology of anencephaly and spina bi-
fida. Br. Med. J. 1: 218, 1976.

125. Ahlgren, M., Kallen, B. and Rannevik, G. Outcome of
pregnancy after Clomiphene therapy. Acta OB-GYN Scand. 55:
371-5, 1976.

126. Elwood, J.M. Clomiphene and anencephalic births.
Lancet 1: 31, 1974.

127. Nightingale, E.O., Scribanu, N., McCullough, D.C.
Observations in Patients with Neural Tube Defects in a Met-
ropolitan hospital clinic: An Epidemiological history.
Dev. Med. Child. Neurol. 17: 574-79, 1975.

128. Holmes, L.B. Etiologic heterogenity of neural tube
defects. N. Engl. J. Med. 294: 365-9, 1976.

129. Gardiner, A., Clarke, C., Cowen, J., Finn, R. and
McKenrick, O.M. Spontaneous abortion and fetal abnormality
in subsequent pregnancies. Br. Med. J. 1: 1016-18, 1978.