The association of low socioeconomic status and the risk of having a child with Down syndrome: a report from the National Down Syndrome Project

PURPOSE

Advanced maternal age and altered recombination are known risk factors for Down syndrome cases due to maternal nondisjunction of chromosome 21, whereas the impact of other environmental and genetic factors is unclear. The aim of this study was to investigate an association between low maternal socioeconomic status and chromosome 21 nondisjunction.

METHODS

Data from 714 case and 977 control families were used to assess chromosome 21 meiosis I and meiosis II nondisjunction errors in the presence of three low socioeconomic status factors: (i) both parents had not completed high school, (ii) both maternal grandparents had not completed high school, and (iii) an annual household income of <$25,000. We applied logistic regression models and adjusted for covariates, including maternal age and race/ethnicity.

RESULTS

As compared with mothers of controls (n = 977), mothers with meiosis II chromosome 21 nondisjunction (n = 182) were more likely to have a history of one low socioeconomic status factor (odds ratio = 1.81; 95% confidence interval = 1.07-3.05) and ≥2 low socioeconomic status factors (odds ratio = 2.17; 95% confidence interval = 1.02-4.63). This association was driven primarily by having a low household income (odds ratio = 1.79; 95% confidence interval = 1.14-2.73). The same statistically significant association was not detected among maternal meiosis I errors (odds ratio = 1.31; 95% confidence interval = 0.81-2.10), in spite of having a larger sample size (n = 532).

CONCLUSION

We detected a significant association between low maternal socioeconomic status and meiosis II chromosome 21 nondisjunction. Further studies are warranted to explore which aspects of low maternal socioeconomic status, such as environmental exposures or poor nutrition, may account for these results.

Preconception folic acid supplementation and risk for chromosome 21 nondisjunction: a report from the National Down Syndrome Project

Both a lack of maternal folic acid supplementation and the presence of genetic variants that reduce enzyme activity in folate pathway genes have been linked to meiotic nondisjunction of chromosome 21; however, the findings in this area of research have been inconsistent. To better understand these inconsistencies, we asked whether maternal use of a folic acid-containing supplement before conception reduces risk for chromosome 21 nondisjunction. Using questionnaire data from the National Down Syndrome Project, a population-based case-control study, we compared the use of folic acid-containing supplements among mothers of infants with full trisomy 21 due to maternal nondisjunction (n = 702) and mothers of infants born with no major birth defects (n = 983). Using logistic regression, adjusting for maternal age, race/ethnicity, and infant age at maternal interview, we found no evidence of an association between lack of folic acid supplementation and maternal nondisjunction among all case mothers (OR = 1.16; 95% CI: 0.90-1.48). In analyses stratified by meiotic stage and maternal age (<35 or ≥35 years), we found an association among older mothers experiencing meiosis II nondisjunction errors (OR = 2.00; 95% CI: 1.08-3.71). These data suggest that lack of folic acid supplementation may be associated specifically with MII errors in the aging oocyte. If confirmed, these results could account for inconsistencies among previous studies, as each study sample may vary by maternal age structure and proportion of meiotic errors.

Lack of maternal folic acid supplementation is associated with heart defects in Down syndrome: a report from the National Down Syndrome Project

BACKGROUND

Maternal folic acid supplementation has been associated with a reduced risk for neural tube defects and may be associated with a reduced risk for congenital heart defects and other birth defects. Individuals with Down syndrome are at high risk for congenital heart defects and have been shown to have abnormal folate metabolism.

METHODS

As part of the population-based case-control National Down Syndrome Project, 1011 mothers of infants with Down syndrome reported their use of supplements containing folic acid. These data were used to determine whether a lack of periconceptional maternal folic acid supplementation is associated with congenital heart defects in Down syndrome. We used logistic regression to test the relationship between maternal folic acid supplementation and the frequency of specific heart defects correcting for maternal race or ethnicity, proband sex, maternal use of alcohol and cigarettes, and maternal age at conception.

RESULTS

Lack of maternal folic acid supplementation was more frequent among infants with Down syndrome and atrioventricular septal defects (odds ratio [OR], 1.69; 95% confidence interval [CI], 1.08-2.63; p = 0.011) or atrial septal defects (OR, 1.69; 95% CI, 1.11-2.58; p = 0.007) than among infants with Down syndrome and no heart defect. Preliminary evidence suggests that the patterns of association differ by race or ethnicity and sex of the proband. There was no statistically significant association with ventricular septal defects (OR, 1.26; 95% CI, 0.85-1.87; p = 0.124).

CONCLUSIONS

Our results suggest that lack of maternal folic acid supplementation is associated with septal defects in infants with Down syndrome. Birth Defects Research (Part A), 2011. © 2011 Wiley-Liss, Inc.

Variation in folate pathway genes contributes to risk of congenital heart defects among individuals with Down syndrome

Cardiac abnormalities are one of the most common congenital defects observed in individuals with Down syndrome. Considerable research has implicated both folate deficiency and genetic variation in folate pathway genes with birth defects, including both congenital heart defects (CHD) and Down syndrome (DS). Here, we test variation in folate pathway genes for a role in the major DS-associated CHD atrioventricular septal defect (AVSD). In a group of 121 case families (mother, father, and proband with DS and AVSD) and 122 control families (mother, father, and proband with DS and no CHD), tag SNPs were genotyped in and around five folate pathway genes: 5,10-methylenetetrahyrdofolate reductase (MTHFR), methionine synthase (MTR), methionine synthase reductase (MTRR), cystathionine beta-synthase (CBS), and the reduced folate carrier (SLC19A1, RFC1). SLC19A1 was found to be associated with AVSD using a multilocus allele-sharing test. Individual SNP tests also showed nominally significant associations with odds ratios of between 1.34 and 3.78, depending on the SNP and genetic model. Interestingly, all marginally significant SNPs in SLC19A1 are in strong linkage disequilibrium (r(2)> or = 0.8) with the nonsynonymous coding SNP rs1051266 (c.80A>G), which has previously been associated with nonsyndromic cases of CHD. In addition to SLC19A1, the known functional polymorphism MTHFR c.1298A was over-transmitted to cases with AVSD (P=0.05) and under-transmitted to controls (P=0.02). We conclude, therefore, that disruption of the folate pathway contributes to the incidence of AVSD among individuals with DS.

Genetic and environmental factors in the etiology of esophageal atresia and/or tracheoesophageal fistula: an overview of the current concepts

Esophageal atresia and/or tracheoesophageal fistula (EA/TEF) are severe congenital anomalies. Although recent years have brought significant improvement in clinical treatment, our understanding of the etiology of these defects is lagging. Many genes and genetic pathways have been implicated in the development of EA/TEF, but only a few genes have been shown to be involved in humans, in animals, or in both. Extrapolating data from animal models to humans is not always straightforward. Environmental factors may also carry a risk, but the mechanisms are yet to be elucidated. This review gives an overview of the current state of knowledge about both genetic and environmental risk factors in the etiology of EA/TEF.

Congenital gastrointestinal defects in Down syndrome: a report from the Atlanta and National Down Syndrome Projects

We report Down syndrome (DS)-associated congenital gastrointestinal (GI) defects identified during a 15 year, population-based study of the etiology and phenotypic consequences of trisomy 21. Between 1989 and 2004, six sites collected DNA, clinical and epidemiological information on live-born infants with standard trisomy 21 and their parents. We used chi-squared test and logistic regression to explore relationships between congenital GI defects and infant sex, race, maternal age, origin of the extra chromosome 21, and presence of a congenital heart defect. Congenital GI defects were present in 6.7% of 1892 eligible infants in this large, ethnically diverse, population-based study of DS. Defects included esophageal atresia/tracheoesophageal fistula (0.4%), pyloric stenosis (0.3%), duodenal stenosis/atresia (3.9%), Hirschsprung disease (0.8%), and anal stenosis/atresia (1.0%). We found no statistically significant associations between these defects and the factors examined. Although not significant, esophageal atresia was observed more often in infants of younger mothers and Hispanics, Hirschsprung disease was more frequent in males and in infants of younger mothers and blacks, and anal stenosis/atresia was found more often among females and Asians.

Non-VACTERL-type anomalies are frequent in patients with esophageal atresia/tracheo-esophageal fistula and full or partial VACTERL association

BACKGROUND

The VACTERL association is the nonrandom co-occurrence of Vertebral anomalies, Anal atresia, Cardiovascular malformations, Tracheo-esophageal fistula (TEF) and/or Esophageal atresia (EA), Renal anomalies, and/or Limb-anomalies. The full phenotype of patients with EA/TEF and other anomalies of the VACTERL spectrum of defects association is not well described in the literature.

METHODS

Data on patients with EA/TEF seen in two pediatric surgical centers in the Netherlands between January 1988 and August 2006 were evaluated for defects of the VACTERL spectrum as well as non-VACTERL-type defects. The presence of two or more defects of the VACTERL spectrum in addition to EA/TEF was the criterion for inclusion in this study. A detailed description was made of all defects.

RESULTS

Of 463 patients with EA and/or TEF, 107 (23.1%) fulfilled the inclusion criterion, of which seventeen cases had a recognized etiology and were excluded, leaving 90 cases (19.4%) for analysis. Other than the esophagus and the trachea, the vertebrae/ribs and the cardiovascular system were most commonly affected (68.9 and 65.6%, respectively). Interestingly, 70% of cases had additional non-VACTERL-type defects, with high occurrences for single umbilical artery (20%), genital defects (23.3%), and respiratory tract anomalies (13.3%).

CONCLUSIONS

Many patients with EA/TEF and at least two other defects of the VACTERL spectrum also display non-VACTERL-type congenital anomalies.

Esophageal atresia and tracheoesophageal fistula in children of women exposed to diethylstilbestrol in utero

OBJECTIVE

This study was undertaken to study the possible risk to mothers exposed in utero to diethylstilbestrol for offspring with esophageal atresia/tracheoesophageal fistula.

STUDY DESIGN

Information on the mothers' in utero exposure to diethylstilbestrol was obtained from 3 sources: questionnaires completed by members of the parents' association of children with esophageal atresia/tracheoesophageal fistula; records of patients with esophageal atresia/tracheoesophageal fistula from a hospital database; and files from the Northern Netherlands EUROCAT birth defects registry.

RESULTS

Three of 124 (2.4%) mothers from the parents' association and 6 of 192 (3.1%) mothers from the hospital cases reported in utero exposure to diethylstilbestrol. For 8848 children registered by EUROCAT, 33 (0.37%) mothers reported in utero exposure to diethylstilbestrol. Of 117 infants with esophageal atresia/tracheoesophageal fistula, 4 (3.4%) had a mother with in utero exposure to diethylstilbestrol; this association was statistically significant (P = .001).

CONCLUSION

We report a possible transgenerational effect of diethylstilbestrol exposure in the cause of some cases of esophageal atresia/tracheoesophageal fistula.

The National Down Syndrome Project: design and implementation

OBJECTIVE

The National Down Syndrome Project (NDSP), based at Emory University in Atlanta, Georgia, represents a multi-site, population-based, case-control study with two major aims: (1) to identify molecular and epidemiological factors contributing to chromosome nondisjunction and the consequent packaging of an extra chromosome into an egg or sperm, and (2) to identify risk factors for Down syndrome-associated birth defects.

METHODS

The six national sites represent approximately 11% of U.S. births. Cases were newborns with Down syndrome (trisomy 21), and controls were infants without major birth defects randomly selected from the same birth populations. Biological samples were collected from case infants and their parents, and genetic markers were typed to determine the parental origin of chromosome 21 nondisjunction. Each site interviewed parents of case and control infants addressing pregnancy, medical and family history, occupation, and exposures. Sites collected medical information on case infants.

RESULTS

The NDSP enrolled 907 infants as cases and 977 infants as controls (participation rates: 60.7% for cases; 56.9% for controls). Participation rates varied widely by site as did important demographic factors such as maternal age, race, and education. Nondisjunction during oogenesis accounted for 93.2% of the cases. Errors in spermatogenesis were found in 4.1%, and 2.7% were post-zygotic errors.

CONCLUSIONS

This exceptional compilation of questionnaire, clinical, and molecular data makes the NDSP a unique resource for ongoing studies of the etiology and phenotypic consequences of trisomy 21. The combined approach increases study power by defining subgroups of cases by the origin of nondisjunction. This report describes the design and successful implementation of the

Interaction between maternal smoking and malnutrition in infant risk of gastroschisis

BACKGROUND

Gastroschisis is a severe birth defect characterized by a tear in the infant's abdominal wall. Young mothers have the highest risk of having an infant with gastroschisis. In an animal model, the defect resulted from exposure of pregnant mice to carbon monoxide (CO) in combination with a low protein and low zinc diet.

METHODS

We evaluated this model in a study of 55 infants with gastroschisis and 94 age-matched controls that included maternal interview with a food frequency questionnaire. Smoking cigarettes (> or = 1 pack/day) or marijuana (more than once) 3 months prior to pregnancy indicated CO exposure. Low protein or zinc intake and a low body mass index (BMI) indicated maternal malnutrition.

RESULTS

When assessed separately, high CO, low protein, low zinc, and low BMI were each significantly associated with an increased risk of gastroschisis. Although we observed significant CO-BMI and CO-zinc interactions after adjusting for income, only a combination of high CO exposure and low BMI yielded a synergistic adverse effect. Compared to the low risk of having an infant with gastroschisis for mothers who did not have low BMI and did not smoke, the risk of having an infant with gastroschisis was 16.3 times (95% CI, 2.49-113.4) higher for mothers who did not have low BMI but smoked, and 19.7 times (95% CI, 4.33-89.6) higher for mothers who did not smoke but had low BMI. However, the risk was 26.5 times (95% CI, 7.85-89.4) higher for mothers who had low BMI and smoked.

CONCLUSIONS

Our results suggest that young mothers are at increased risk of having an infant with gastroschisis if they smoke and are also malnourished.

Selected gene polymorphisms and their interaction with maternal smoking, as risk factors for gastroschisis

BACKGROUND

Gastroschisis is a severe birth defect in which the infant is born with a portion of the intestines extruding through a small tear in the abdominal wall, usually to the right of the umbilical cord. Its etiology is unknown, but the prevailing hypothesis is that it results from a vascular accident at the time of involution of the right umbilical vein or of the development of the superior mesenteric artery.

METHODS

In a case-control study of 57 cases of gastroschisis and 506 controls, we tested DNA for polymorphisms of 32 genes representing enzymes involved in angiogenesis, blood vessel integrity, inflammation, wound repair, and dermal or epidermal strength.

RESULTS

In logistic regression, controlling for maternal ethnicity, and using the homozygote wild-type as referent, the following gene polymorphisms were associated with an increased risk for a gastroschisis for heterozygotes: ICAM1 gly241arg (odds ratio [OR], 1.9; 95% confidence interval [CI], 1.1 -3.4); NOS3 glu298asp (OR, 1.9; 95% CI, 1.1-3.4); NPPA 2238T > C (OR, 1.9; 95% CI, 1.0-3.4); and ADD1 gly460trp (OR, 1.5; 95% CI, 0.8-2.8). Additionally, for the NPPA and ADD1 single-nucleotide polymorphisms (SNPs), the homozygote variants had a significantly higher risk than the heterozygotes (OR, 7.5; 95% CI, 1.7-33.5 and OR, 4.9; 95% CI, 1.9-12.9, respectively). Three SNPs showed a strong interaction with maternal smoking. The risk for smokers with 1 or 2 variant alleles compared to nonsmokers with the wild-type allele were: NOS3 (OR, 5.2; 95% CI, 2.4-11.4); ICAM1 (OR, 5.2; 95% CI, 2.1-12.7); and NPPA (OR, 6.4; 95% CI, 2.8-14.6).

CONCLUSIONS

These results support the hypothesis of a vascular compromise as part of a multifactorial etiology of gastroschisis involving both genes and environmental factors.

Maternal meiosis II nondisjunction in trisomy 21 is associated with maternal low socioeconomic status

PURPOSE

We evaluated whether the association of socioeconomic risk factors for trisomy 21 differed by type of maternal meiotic error.

METHODS

We determined meiotic errors by DNA analysis for 150 trisomy 21 cases, and maternal lifetime exposures to low socioeconomic factors by questionnaire.

RESULTS

Mothers of meiosis II cases were significantly more likely to be exposed to four low socioeconomic factors than mothers of meiosis I cases (odds ratio = 9.50; 95% confidence interval = 1.8-49.8).

CONCLUSION

Maternal lifetime exposure to poor socioeconomic environment is a risk factor for a trisomy 21, particularly if nondisjunction leads to a maternal meiosis II.

Mutations in PITX2 may contribute to cases of omphalocele and VATER-like syndromes

Omphalocele is a congenital anomaly with substantial morbidity. Rieger syndrome, an autosomal dominant disorder, is characterized by craniofacial abnormalities and abdominal wall defects. PITX2 mutations are etiologic in >40% of cases of Rieger syndrome. We demonstrate that the birth prevalence of omphalocele is significantly higher in Rieger syndrome than in the general population, with omphaloceles found in 0.03% in the Iowa newborn population and 4.3% of patients with Rieger syndrome. Our objective was to screen coding and conserved non-coding regions of PITX2 for mutations in 209 patients with omphalocele. We identified remarkable evolutionarily conserved regions by comparing the 3'UTR of Pitx2 in 13 vertebrate and 3 invertebrate species. No mutations changing the amino acid sequence were found within the omphalocele population. In one case of omphalocele with VATER-like additional anomalies, a three nucleotide deletion was found in the 3'UTR. This deletion was not seen in 1,186 controls. Also in the 3'UTR, we identified a single nucleotide polymorphism at a highly conserved residue. Our findings suggest additional studies of PITX2 conserved regions will be valuable. We also screened the omphalocele cases for mutations in exon 5 of the gene FLNA. Mutations in FLNA have been shown to cause a broad range of congenital malformations, including otopalatodigital syndrome type 2 in which a missense mutation occurring in exon 5 of FLNA results in omphalocele as part of the phenotype. We did not find any mutations in exon 5 of FLNA in 179 omphalocele cases studied.

Association of congenital diaphragmatic hernia with limb-reduction defects

BACKGROUND

The pathogenesis of congenital diaphragmatic hernia (CDH), a severe birth defect, is not well understood; however, both developmental genes and environmental factors have been suggested to be involved. CDH is frequently associated with malformations of other structures, such as limbs, whose embryogenesis is better understood. An examination of the co-occurrence of developmental defects may provide clues as to the origin and timing of the insult to the diaphragm and limbs. Our focus was on CDH-associated limb-reduction defects (LRDs).

METHODS

For this descriptive study, we reviewed the medical records of infants with a posterolateral (Bochdalek) CDH and an associated LRD among 146 patients from the Sophia Children's Hospital, and among 810 infants and 36 stillbirths from the California Birth Defects Monitoring Program (CBDMP).

RESULTS

In the hospital group, 14 patients (10%) had an associated limb defect, of which about one-third were LRDs (of these, most were of a nonsevere type, such as hypoplasia of fingers). In the registry group, a limb defect was found in 162 cases (18.5%), 18 of which were mostly severe LRD (usually of the upper extremities). Additional congenital anomalies were observed in all CDH-LRD cases in both groups.

CONCLUSIONS

In the registry group, 77.8% of LRDs were either bilateral or ipsilateral, and were mostly preaxial, suggesting an early embryological insult affecting both precursor anlages. These results, from large numbers of cases, support the notion of a developmental association between CDH and LRD, as has been observed in several knockout mice. Future analyses of candidate genes from patients with CDH and LRD may elucidate this developmental association in humans.

Fetal Trisomy 21 and Maternal Preeclampsia

BACKGROUND

Placental trophoblast shedding into maternal circulation has been hypothesized as a potential cause of preeclampsia. Because pregnancies with a trisomy 21 fetus also have high levels of fetal cells and cell-free fetal DNA in maternal circulation, we examined whether trisomy 21 pregnancies have a higher risk of preeclampsia than euploid pregnancies.

METHODS

We used 2 population-based databases. We identified 7763 pregnancies with a singleton trisomy 21-affected fetus and 15,293 matched euploid gestations from the U.S. Natality files for the period 1995-1999. The second database consisted of 665 pregnancies with fetal trisomy 21 and 987 euploid controls in a population-based Down syndrome study in California. In the latter study, women were interviewed by telephone regarding characteristics and pregnancy complications. Gestational hypertension and preeclampsia are the outcomes of this study.

RESULTS

The U.S. Natality files showed that in nulliparous women fetal trisomy 21 was associated with a reduced risk of pregnancy-induced hypertension (adjusted relative risk [aRR] = 0.67; 95% confidence interval [CI] = 0.53 to 0.85). Findings from the California study confirmed this association in nulliparous women, and further revealed that the decrease in overall risk of pregnancy-induced hypertension was mainly the result of a large reduction in the risk of preeclampsia (aRR = 0.19; CI = 0.04 to 0.88) rather than in gestational hypertension by itself (0.83; 0.37 to 1.84). Neither dataset showed these effects among multiparous pregnancies.

CONCLUSION

Fetal trisomy 21 is associated with a reduced, rather than increased, risk of preeclampsia, specifically in nulliparous women.

Hypospadias in California

BACKGROUND

The occurrence of hypospadias has been reported to be increasing. The objectives of this study were to extend the literature on the descriptive epidemiology of hypospadias and to determine whether its birth prevalence increased in California in recent years. We used actively ascertained, population-based data for which detailed clinical descriptions permitted careful phenotypic classifications.

METHODS

We examined registry data on 5838 male live births and stillbirths that occurred in California from 1984 through 1997. To reduce pathogenic heterogeneity, cases were classified as mild, severe, or not otherwise specified based on the anatomic position of the urethral opening. We also classified cases as isolated or nonisolated based on the presence and type of accompanying malformations. We used multivariable Poisson regression analysis to examine time trends and risk factors.

RESULTS

There was no evidence for an increase in prevalence of any of the case groups between 1989 and 1997. The adjusted relative risk (RR) for change in prevalence per year of isolated severe cases was 0.99 (95% confidence interval = 0.96-1.03). Adjusted RRs indicated increased risks for specific types of hypospadias with maternal non-Hispanic white race-ethnicity, higher education, older age, and nulliparity. Delivery before 37 weeks and multiple births tended either not to be associated with risk or to be associated with reduced risk. Lower birthweight was associated with increased risk for all case groups.

CONCLUSIONS

This study suggests that hypospadias prevalence has not been increasing in California in recent years. Differences by phenotype suggest that examining certain phenotypes separately could help to understand hypospadias etiology.

Socioeconomic effects on the risk of having a recognized pregnancy with Down syndrome

BACKGROUND

Appoximately 95% of Down syndrome (DS) cases are caused by an error in germ cell division (meiosis), resulting in an extra chromosome 21. The meiotic error, predominantly of maternal origin, occurs either during the mother's fetal life (meiosis I) or at ovulation (meiosis II). Because maternal-age-specific DS prevalence rates vary between and within populations, it has been hypothesized that environmental factors can affect the risk for a DS pregnancy.

METHODS

In a population-based case-control study of 997 clinically recognized DS cases (including fetal losses) and 1007 controls without a birth defect, we examined the mother's socioeconomic status (SES) from the time of her fetal life to the time of conception. SES variables were considered as proxies for environmental factors. We used multiple logistic regression for the analyses.

RESULTS

We found associations with low levels of each SES variable examined: mother's education less than high school (OR, 1.29; 95% CI, 1.01-1.65), father's low occupation (OR, 1.23; 95% CI, 0.95-1.60), father's low education (OR, 1.28; 95% CI, 0.99-1.64), mother's father's low occupation (OR, 1.35; 95% CI, 1.06-1.71), and family income <$20,000 (OR, 1.31; 95% CI, 1.02-1.68) [corrected]. The risk for DS increased as the number of low socioeconomic factors present throughout the mother's life increased. With four factors present, the risk (adjusted for confounders) almost doubled (OR, 1.98; 95% CI, 1.30-3.01). Those associations persisted among young (< 30) and old (> or = 30) maternal age groups.

CONCLUSIONS

A mother's low SES during any period before conception increases her risk for a recognized pregnancy with DS. Because of the high birth prevalence of DS, the public health impact of maternal SES may be considerable.

Effect of maternal smoking and coffee consumption on the risk of having a recognized Down syndrome pregnancy

To evaluate the possible effects of maternal smoking and caffeine or coffee consumption on the occurrence of a recognized pregnancy with Down syndrome, the authors analyzed data from a case-control study of 997 liveborn infants or fetuses with Down syndrome ascertained in California from 1991 to 1993 and 1,007 liveborn controls without a birth defect. Interviews with mothers covered demographic information, pregnancy, and medical history, with detailed questions on the use of tobacco, alcohol, and caffeinated beverages. All analyses were age-adjusted. High alcohol consumption (> or =4 drinks/week) in the first month of pregnancy was associated with reduced risk for a recognized Down syndrome conceptus (odds ratio (OR) = 0.54; 95% confidence interval (CI): 0.34, 0.85). Maternal smoking during the periconceptional period was not associated with risk of recognized Down syndrome (OR = 1.04; 95% CI: 0.79, 1.37), but maternal consumption of four or more cups of coffee per day was inversely associated (OR = 0.63; 95% CI: 0.41, 0.96). In multivariate analysis, a significant interaction between coffee drinking and smoking was observed. The inverse association remained only for nonsmoking mothers who drank four or more cups of coffee per day (OR = 0.48; 95% CI: 0.28, 0.82). These results suggest that among nonsmoking mothers, high coffee consumption is more likely to reduce the viability of a Down syndrome conceptus than that of a normal conceptus.

Polymorphisms in genes involved in folate metabolism as maternal risk factors for Down syndrome

Down syndrome is a complex genetic and metabolic disorder attributed to the presence of three copies of chromosome 21. The extra chromosome derives from the mother in 93% of cases and is due to abnormal chromosome segregation during meiosis (nondisjunction). Except for advanced age at conception, maternal risk factors for meiotic nondisjunction are not well established. A recent preliminary study suggested that abnormal folate metabolism and the 677C-->T polymorphism in the methylenetetrahydrofolate reductase (MTHFR) gene may be maternal risk factors for Down syndrome. The present study was undertaken with a larger sample size to determine whether the MTHFR 677C-->T polymorphism was associated with increased risk of having a child with Down syndrome. Methionine synthase reductase (MTRR) is another enzyme essential for normal folate metabolism. A common polymorphism in this gene was recently associated with increased risk of neural tube defects and might also contribute to increased risk for Down syndrome. The frequencies of the MTHFR 677C-->T and MTRR 66A-->G mutations were evaluated in DNA samples from 157 mothers of children with Down syndrome and 144 control mothers. Odds ratios were calculated for each genotype separately and for potential gene-gene interactions. The results are consistent with the preliminary observation that the MTHFR 677C-->T polymorphism is more prevalent among mothers of children with Down syndrome than among control mothers, with an odds ratio of 1.91 (95% confidence interval [CI] 1.19-3.05). In addition, the homozygous MTRR 66A-->G polymorphism was independently associated with a 2. 57-fold increase in estimated risk (95% CI 1.33-4.99). The combined presence of both polymorphisms was associated with a greater risk of Down syndrome than was the presence of either alone, with an odds ratio of 4.08 (95% CI 1.94-8.56). The two polymorphisms appear to act without a multiplicative interaction.

A low pregnancy body mass index is a risk factor for an offspring with gastroschisis

A mother's prepregnancy obesity has been suggested as a risk factor for having offspring with an abdominal wall defect. We evaluated this hypothesis among 104 cases of gastroschisis--a severe birth defect of the abdominal wall most prevalent in infants of young women--and 220 controls with no defect. Using Quetelet's index (QI = weight in kg/height in m2) as a measure of body mass, we found a higher risk of gastroschisis (odds ratio (OR) = 3.2; 95% confidence interval (CI) = 1.4-7.3) for underweight mothers (QI<18.1 kg/m2) and a lower risk (OR = 0.2; 0.05-0.9) for overweight mothers (QI>28.3 kg/m2) as compared with mothers of normal weight. As QI was correlated to height, with the correlation varying according to mother's ethnicity and age, we adjusted for these factors in the analysis; the adjusted values approximated the unadjusted values. Evaluation of QI as a continuous variable showed that, for every unit increase in QI, the risk for gastroschisis decreased by about 11%. Sociodemographic, pregnancy, and nutrient factors did not confound the association. These results suggest that low prepregnancy body mass rather than obesity is a risk factor for gastroschisis.

Malrotation in conjunction with esophageal atresia/tracheo-esophageal fistula

Esophageal atresia or tracheo-esophageal fistula (EA/TEF) often occurs in association with a well-defined group of other anomalies. We report the prevalence of malrotation and other intestinal anomalies in a large data series comprising 632 nontrisomic infants with EA/TEF ascertained by the California Birth Defects Monitoring Program from January 1, 1983 to December 31, 1994. Consistent with findings reported previously in smaller case series, our findings showed a notable prevalence of imperforate anus (9.0%) and duodenal atresia (5.2%), among other gastrointestinal defects. They also showed a previously unrecognized high prevalence of intestinal malrotation (4.4%). Compared with other infants studied, the infants with EA/TEF and malrotation of the intestine had a higher proportion of other associated anomalies (in particular intestinal, central nervous system, vertebral and rib, renal and genital anomalies). These findings indicate that intestinal malrotation is more common in infants with EA/TEF than is generally perceived, and that intestinal malrotation in an infant with EA/TEF is associated with a higher burden of additional congenital anomalies, suggesting that this group of infants may have more pervasive developmental deficits and poorer prognosis than has previously been recognized.

Maternal risk factors and major associated defects in infants with Down syndrome

More than 50% of infants with Down syndrome have associated defects that cause considerable morbidity and mortality. We evaluated the hypothesis that the trisomic genome interacts with environmental factors to increase the risk for specific associated defects. We evaluated risk factors present during early pregnancy in a multiracial population of 687 infants with Down syndrome. Mother's cigarette smoking was associated with the grouped cardiac defects [odds ratio (OR)=2.0; 95% confidence interval (CI) = 1.2-3.2]. When adjusted for other cardiac defects and maternal race, the following specific defects were associated with smoking: atrioventricular canal (OR = 2.3; 95% CI = 1.2-4.5), tetralogy of Fallot (OR = 4.6; 95% CI = 1.2-17.0), and atrial septal defects without ventricular septal defect (OR = 2.2; 95% CI = 1.1-4.3). Hirschsprung disease was associated with mother's daily consumption of more than three cups of coffee (OR = 6.02; 95% CI = 1.2-29.7) and with mother's fever (OR = 3.4; 95% CI = 0.7-16.4), but the number of cases was small. Use of alcohol was not associated with any defect. Mother's race, age, parity, income, or education did not confound the associations. Results suggest that environmental factors can modify the occurrence of associated anomalies in the embryo with Down syndrome.

Association between mothers' nutrient intake and their offspring's risk of gastroschisis

The young age of mothers of infants with gastroschisis, a congenital defect of the abdominal wall, suggested that deficient nutrition, with maternal-fetal competition for nutrients, could be a risk factor for gastroschisis. This population-based hypothesis-generating study consisted of 55 cases of gastroschisis and 182 matched controls. We assessed maternal nutrient intake during the trimester before conception with a self-reported food-frequency questionnaire and screened 38 nutrients to identify those most likely to be associated with gastroschisis. We used statistical classification trees to empirically generate cutpoints that determined the low and high levels of nutrient intakes corresponding to the risk of gastroschisis; cutpoints for most nutrients were similar to the corresponding recommended daily dietary allowances (RDAs). In univariate analysis, low intake of several nutrients emerged as the leading risk factors: carotenoids, e.g., alpha-carotene (odds ratio (OR) = 4.6; 95% confidence interval (CI) = 2.2-9.5), beta-carotene (OR = 3.1; 95% CI = 1.6-6.0); amino-acid compounds, e.g., total glutathione (OR = 3.5; 95% CI = 1.7-7.2); vitamin C (OR = 2.2; 95% CI = 1.5-7.8); vitamin E (OR = 2.3; 95% CI = 1.2-4.4); and minerals, fiber, and the fruit-and-vegetable group (OR = 3.1; 95% CI = 1.5-6.2). High intake of nitrosamines (OR = 2.4; 95% CI = 1.3-4.5) was also a good candidate. Many nutrient values were correlated and, in multivariate analysis, those most associated with gastroschisis were low alpha-carotene (OR = 4.3; 95% CI = 1.9-9.8), low total glutathione (OR = 3.3; 95% CI = 1.4-7.6), and high nitrosamines (OR = 2.6; 95% CI = 1.3-5.4). Adjusting for variables associated with gastroschisis in previous analyses of this population did not substantially alter those risks. These results suggest that maternal dietary inadequacy may be a risk factor for gastroschisis, and the three nutrients that emerged from the nutrient screening appear to be the best candidates to examine in further epidemiological analyses or biological studies.

Anomalies in Down syndrome individuals in a large population-based registry

In a population of close to 2.5 million infants born from 1983 to 1993 registered in the California Birth Defects Monitoring Program, we compared the prevalence of structural birth defects among 2,894 infants with Down syndrome (DS) with that of infants without DS. Among 61 defects uniformly ascertained in affected and unaffected infants, 45 were significantly more common in DS, with atrioventricular canal (risk ratio = 1,009), duodenal atresia (risk ratio = 265), and annular pancreas (risk ratio = 430) being the most common. Most defects of blastogenesis and most midline defects were either nonsignificantly associated or not observed in infants with DS. Theories on the pathogenesis of defects in trisomies must account for the lack of and for the presence of specific defects.

Is there an association of Down syndrome and omphalocele?

The possible association of Down syndrome (DS) with omphalocele is controversial. We reviewed the 2,979 live births and stillbirths with DS born from 1983 to 1993 in the catchment area of the California Birth Defects Monitoring Program (CBDMP). We observed one infant with both defects, a number that did not differ significantly from what was expected (P < 0.40). We also reviewed the pathological reports of one of us (L.H.H.) from a series of 36 DS fetuses and neonatal deaths; none had an omphalocele. We then reviewed the literature for epidemiological studies of DS and for epidemiological, surgical, prenatal, and familial studies of omphalocele. Possible biases inherent in each type of study were evaluated. The majority of epidemiological studies showed no association of DS with omphalocele. In surgical series, the occasional infant with both defects was more likely to undergo surgery than infants with omphalocele and trisomies 13 and 18 or other severe birth defects. Inclusion of both omphalocele and umbilical hernia in the same ICD-9 code may explain some of the correlations with DS noticed in a few epidemiological studies. In conclusion, our data suggest that trisomy 21 does not predispose the fetus to an increased risk for an omphalocele.

The epidemiology of infantile hypertrophic pyloric stenosis

Infants with infantile hypertrophic pyloric stenosis (IHPS) born from 1983 to 1988 and recorded in the California Birth Defects Monitoring Program (CBDMP) database were compared with their birth cohort by demographic characteristics and selected associated birth defects. We identified 1963 cases of IHPS for a cumulative incidence of 1.9 per 1000 livebirths. The cumulative incidence per 1000 livebirths was 2.4 in White, 1.8 in Hispanic, 0.7 in Black, and 0.6 in Asian infants. Between weeks 3-12 after birth, 1871 (95%) IHPS cases were diagnosed. Premature infants were diagnosed with IHPS later than term or post-term infants. The incidence of IHPS declined for those born to maternal age groups of > or = 25 years and, independently, for successive birth ranks. The probandwise concordance rate for IHPS in monozygous twins was less than unity (0.25-0.44), although higher than the concordance for dizygous twins (0.05-0.10). The incidence of Smith-Lemli-Opitz syndrome (SLO) diagnosed in infants with IHPS (3 of 1963) was 157-fold higher than the incidence of SLO diagnosed in the CBDMP population. IHPS occurs in all of the largest racial and ethnic groups in California, most frequently in White and Hispanic infants. Pyloric stenosis presents only within a brief phase of development, which may be delayed in premature infants. A predominant discordance of disease state in monozygous twins implies an aetiological role for undetermined environmental factors. The association between SLO, caused by deficient cholesterol synthesis, and IHPS deserves additional study. Infants with suspected SLO require close observation for the onset of IHPS.

Maternal medications and environmental exposures as risk factors for gastroschisis

In a case-control study of gastroschisis, we evaluated the risks associated with mother's first-trimester use of medications and with hobby or occupational exposures for 110 cases and 220 controls without a birth defect. Mothers of cases and controls were age-matched. For hobby or occupational exposures, we found significantly elevated risks for high levels of solvents (odds ratio (OR) = 3.8; 95% confidence interval (CI) = 1.6-9.2) and for colorants (OR = 2.3; 95% CI = 1.3-4.0). For medications, we found significantly elevated risks for two strong cyclooxygenase inhibitors, aspirin (OR = 4.7; 95% CI = 1.2-18.1) and ibuprofen (OR = 4.0; 95% CI = 1.0-16.0), but not for acetaminophen, a weak cyclooxygenase inhibitor. Periconceptional exposure to X rays was also associated with gastroschisis (OR = 2.5; 95% CI = 1.2-5.5), but exposure to antibiotics, antinauseants, sulfonamides, or oral contraceptives was not. We also found elevated risks for two decongestants, pseudoephedrine (OR = 2.1; 95% CI = 0.8-5.5) and phenylpropanolamine (OR = 10.0; 95% CI = 1.2-85.6). For the group of all decongestants, including also oxymetazoline and ephedrine, the risk was significantly elevated (OR = 2.4; 95% CI = 1.0-5.4). Controlling in multivariate analyses for several demographic and pregnancy variables associated with gastroschisis in a previous analysis [Torfs et al. (1994) Teratology 50: 44-53] did not substantially change the level or direction of the associations. Most of these associations are for vasoactive substances, which supports a vascular hypothesis for the pathogenesis of gastroschisis.

Sex ratios in fetuses and liveborn infants with autosomal aneuploidy

Ten data sources were used substantially to increase the available data for estimating fetal and livebirth sex ratios for Patau (trisomy 13), Edwards (trisomy 18), and Down (trisomy 21) syndromes and controls. The fetal sex ratio estimate was 0.88 (N = 584) for trisomy 13, 0.90 (N = 1702) for trisomy 18, and 1.16 (N = 3154) for trisomy 21. All were significantly different from prenatal controls (1.07). The estimated ratios in prenatal controls were 1.28 (N = 1409) for CVSs and 1.06 (N = 49427) for amniocenteses, indicating a clear differential selection against males, mostly during the first half of fetal development. By contrast, there were no sex ratio differences for any of the trisomies when comparing gestational ages < 16 and > 16 weeks. The livebirth sex ratio estimate was 0.90 (N = 293) for trisomy 13, 0.63 (N = 497) for trisomy 18, and 1.15 (N = 6424) for trisomy 21, the latter two being statistically different than controls (1.05) (N = 3660707). These ratios for trisomies 13 and 18 were also statistically different than the ratio for trisomy 21. Only in trisomy 18 did the sex ratios in fetuses and livebirths differ, indicating a prenatal selection against males > 16 weeks. No effects of maternal age or race were found on these estimates for any of the fetal or livebirth trisomies. Sex ratios for translocations and mosaics were also estimated for these aneuploids. Compared to previous estimates, these results are less extreme, most likely because of larger sample sizes and less sample bias. They support the hypothesis that these trisomy sex ratios are skewed at conception, or become so during embryonic development through differential intrauterine selection. The estimate for Down syndrome livebirths is also consistent with the hypothesis that its higher sex ratio is associated with paternal nondisjunction.

Population-based study of tracheoesophageal fistula and esophageal atresia

From a multiracial population of 1,035,384 births monitored by the California Birth Defects Monitoring Program (CBDMP) from 1983 to 1988, we ascertained 34 cases of esophageal atresia (EA), 204 cases of tracheoesophageal fistula (TEF) with an EA (TEF/EA), and 54 cases of TEF without EA. The total prevalence rate was 2.82 per 10,000 live births and stillbirths and showed no secular trend nor marked seasonal variation. Rates of multiple birth were high for each defect (TEF 3.7%, TEF/EA 4.9%, EA 8.8%; population 1.1%). Non-Hispanic whites were overrepresented for TEF and TEF/EA, but not for EA. Excluding trisomies, mean maternal age was above the population mean (26.8 years) for TEF (27.9 years) and TEF/EA (28.0 years), but not for EA (26.2 years). The proportion of trisomies was significantly higher for EA (23.5%) than for TEF (9.3%; P < 0.02) or for TEF/EA (7.4%; P < 0.003). We subdivided each defect into five mutually exclusive types: isolated, multiple, syndromic, chromosomal, and trisomic. Male-to-female (M/F) ratios varied considerably between types, both within and between defects. The highest M/F ratios within each defect were for the multiple type (TEF 2.29, TEF/EA 1.44, EA 1.33; population 1.05), and the lowest for trisomies (TEF 0.25; TEF/EA 0.25, and EA 0.60). All types except trisomies were significantly associated with a single umbilical artery. We found an association of EA and TEF/EA with dextrocardia (3.1% of cases), and confirmed the association of primary hydrocephalus with TEF and TEF/EA (2.7% of cases). The proportion of cases with additional midline defects or VATER or VACTERL type anomalies was similar for all three defects, suggesting a common developmental pathogenesis. Epidemiologic differences between defects, and between types within defects, may reflect differences in timing of the pathological process or differences in susceptibilities (e.g., by sex or aneuploidy) and emphasize the need to evaluate each defect and its types separately in epidemiologic studies.

A population-based study of gastroschisis: demographic, pregnancy, and lifestyle risk factors

Gastroschisis, an abdominal wall defect, most often occurs in infants of young mothers. To identify risk factors for gastroschisis, we conducted a case-control study in the population surveyed by the California Birth Defects Monitoring Program (CBDMP). From structured questionnaire data, we compared sociodemographic, reproductive, and lifestyle factors for 110 mothers of infants with gastroschisis with those for 220 age-matched mothers of normal infants. Univariate matched-pair analysis showed significant associations of gastroschisis with mother's education, yearly family income, marital status, a history of mother's mother smoking, mother's father's absence from home during the mother's youth, more than one elective abortion, a short interval between menarche and first pregnancy, siblings from different fathers, and use of either a recreational drug (either cocaine, amphetamine, marijuana, or LSD), alcohol, or tobacco during the trimester preceding pregnancy. For cocaine, amphetamine, and marijuana, use of more than one drug showed a stronger association than single drug use. The association was stronger if both parents used drugs. Although many variables were correlated, odds ratios (OR) were significant (95% confidence intervals) in multivariate conditional logistic analysis for: yearly family income < $10,000 [OR = 4.34 (1.54, 12.22)] or $10,000-$49,999 [OR = 3.93 (1.43, 10.80)]; mother's mother's smoking status not known [OR = 3.99 (1.66, 9.56)]; mother's father's absence from home during her youth [OR = 3.11 (1.14, 8.46)]; and drug use by mother [OR = 2.21 (1.21, 4.03)], father [OR = 1.66 (1.02, 2.69)], or both [OR = 3.05 (1.48, 6.28)]. The best predictive model explained 32% of the deviance. Young, socially disadvantaged women with a history of substance use were at highest risk for a child with a gastroschisis.

Possible association between the hernia of Morgagni and trisomy 21

Of the 5 liveborn infants with the hernia of Morgagni recorded in the California Birth Defects Monitoring Program, 3 had trisomy 21. This significant association (P < 10(-6)) between the hernia of Morgagni and trisomy 21 may reflect defective dorsoventral migration of rhabdomyoblasts from the paraxial myotomes, caused by increased cellular adhesiveness in trisomy 21.

A population-based study of congenital diaphragmatic hernia

From 1983 through 1987, in a California population of 718,208 births, 237 infants were born with a congenital diaphragmatic hernia (CDH), a birth prevalence of 3.30 per 10,000 total births (live births and stillbirths). We proposed that the various types of this defect, characterized by their different pathogeneses, would be reflected in differences in their descriptive epidemiologies. We evaluated various demographic, maternal, and infant characteristics for three major types of defects, the Morgagni hernia, the pars sternalis hernia, and the posterolateral hernia, categorizing the latter type into isolated defect (N = 129), multiple congenital anomalies including nonchromosomal syndromes (N = 86), trisomies (N = 10), and chromosomal anomalies other than trisomies (N = 2). For the posterolateral hernia, we present the distribution of associated anomalies (43%) and specifically of midline defects (19%). Although the number of cases for the Morgagni hernia (N = 5) and the pars sternalis hernia (N = 5) were small, comparisons with the posterolateral hernia suggested lower sex ratios, of borderline significance for the pars sternalis hernia (P < 0.09), and higher mean maternal ages for both groups. Within the posterolateral type, we found a significantly higher male to female ratio (M/F = 1.58) only for the isolated subgroup compared to the population (P < 0.03), and a borderline significant rural/urban difference in prevalences (2.12 vs. 1.45 per 10,000) (P < 0.06). Additionally, the distribution of monthly prevalence rates adjusted for gestational age suggested opposite seasonal trends between the isolated and the other posterolateral hernias; within this latter subgroup the difference between the highest monthly rate (1.68) and the lowest (0.96) was of borderline significance (P < 0.09). Our results suggest the need to consider the respective types and subgroups of CDH separately in epidemiologic studies.

Familial cases of gastroschisis in a population-based registry

Only a few familial cases of gastroschisis have been reported. Consequently, the risk of a recurrence has been thought to be very small. In a population-based study of gastroschisis that included an extended pedigree of all probands, 6 (4.7%) out of 127 families had more than one affected relative. The relationships of the affected were: sib, half-sib (2), first cousin, second cousin once removed, and great uncle. Sib recurrence was 3.5%. Our results suggest that pregnancies occurring in a family with a history of gastroschisis may be at higher risk of recurrence than previously thought.

A population-based study of congenital diaphragmatic hernia

From 1983 through 1987, in a California population of 718,208 births, 237 infants were born with a congenital diaphragmatic hernia (CDH), a birth prevalence of 3.30 per 10,000 total births (live births and stillbirths). We proposed that the various types of this defect, characterized by their different pathogeneses, would be reflected in differences in their descriptive epidemiologies. We evaluated various demographic, maternal, and infant characteristics for three major types of defects, the Morgagni hernia, the pars sternalis hernia, and the posterolateral hernia, categorizing the latter type into isolated defect (N = 129), multiple congenital anomalies including nonchromosomal syndromes (N = 86), trisomies (N = 10), and chromosomal anomalies other than trisomies (N = 2). For the posterolateral hernia, we present the distribution of associated anomalies (43%) and specifically of midline defects (19%). Although the number of cases for the Morgagni hernia (N = 5) and the pars sternalis hernia (N = 5) were small, comparisons with the posterolateral hernia suggested lower sex ratios, of borderline significance for the pars sternalis hernia (P < 0.09), and higher mean maternal ages for both groups. Within the posterolateral type, we found a significantly higher male to female ratio (M/F = 1.58) only for the isolated subgroup compared to the population (P < 0.03), and a borderline significant rural/urban difference in prevalences (2.12 vs. 1.45 per 10,000) (P < 0.06). Additionally, the distribution of monthly prevalence rates adjusted for gestational age suggested opposite seasonal trends between the isolated and the other posterolateral hernias; within this latter subgroup the difference between the highest monthly rate (1.68) and the lowest (0.96) was of borderline significance (P < 0.09). Our results suggest the need to consider the respective types and subgroups of CDH separately in epidemiologic studies.

Thyroid antibodies as a risk factor for Down syndrome and other trisomies

To test whether the presence of thyroid antibodies in a parent is a risk factor for meiotic nondisjunction, we measured the levels of thyroid antibodies in serum samples drawn during early pregnancy from 101 gravidas who delivered a child with a trisomy, from 11 gravidas who had had a trisomic child in a previous pregnancy, and from 44 of their husbands. For each case mother, three controls were randomly selected from the same population and matched for age, race, sex of the child, and hospital of birth. Cases and controls came from two longitudinal populations, the Child Health and Development Studies (CHDS) and the national Collaborative Perinatal Project (CPP), together comprising more than 70,000 live births. All cases with both a definite diagnosis of trisomy-Down syndrome (DS) or other-and available serum were included. Overall, there was no association between the presence of thyroid antibodies in a mother and a trisomy in her offspring (odds ratio [OR] = .98, confidence interval [CI] = .54-1.85). The lack of association was seen in all three subgroups (DS only, other trisomies, and DS in a previous pregnancy), in all ethnic groups, and in the age groups of white mothers either less than 30 years of age (OR = .80, CI = .40-1.6) or greater than or equal to 30 years of age (OR = 1.26, CI = .82-1.9). In the CHDS population, case fathers, as compared with control fathers, did not have a higher prevalence of thyroid antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)

Prenatal and perinatal factors in the etiology of cerebral palsy

Among 19,044 children born to mothers with monitored pregnancies and followed medically for at least 5 years, 41 (0.2%) had cerebral palsy that was not the result of a progressive disease or of a neural tube defect. All children without cerebral palsy were entered as controls subjects in the analysis. Significant prenatal or gestational predictors of cerebral palsy were a severe or nonsevere birth defect other than cerebral palsy or its sequelae, low birth weight, low placental weight, abnormal fetal position, and premature separation of the placenta. Maternal antecedents of cerebral palsy were unusually long or unusually short intervals between pregnancies and unusually long menstrual cycles. Perinatal risk factors were delayed crying as a measure of birth asphyxia and abnormal delivery. Children who had seizures within 48 hours of birth were at high risk for the development of cerebral palsy. Seventy-eight percent of children with cerebral palsy did not have birth asphyxia, and the 22% who did had other prenatal risk factors that may have compromised their recovery.

Genetic interrelationship between insulin-dependent diabetes mellitus, the autoimmune thyroid diseases, and rheumatoid arthritis

To investigate the possible coinheritance of autoimmune diseases that are associated with the same HLA antigen, we studied 70 families in which at least two siblings had either type I diabetes mellitus (IDDM), autoimmune thyroid disease (ATD), rheumatoid arthritis (RA), or a combination of these diseases. HLA-A, B, and C typing was performed on all affected sibs in one generation or more. First, we estimated by sib-pair analysis the disease allele frequency (pD) and the mode of inheritance for each disease. According to the method of ascertainment entered into the analysis, the pD for ATD ranged from .120 to .180, for an additive (dominant) mode of inheritance. For RA, the pD ranged from .254 to .341, also for additive inheritance, although recessive inheritance could not be excluded. For IDDM, the pD ranged from .336 to .337 for recessive inheritance; additive inheritance was rejected. Second, we examined the distribution of shared parental haplotypes in pairs of siblings that were discordant for their autoimmune diseases. The results suggested that the same haplotype may predispose to both IDDM and ATD, or IDDM and RA, but not to both RA and ATD. Analysis of pedigrees supported this hypothesis. In 16 families typed for HLA-DR also, the haplotype predisposing to both IDDM and ATD was assigned from pedigree information to DR3 (44%), DR4 (39%), or DR5, DR6, or DR7 (5.5% each). In some families, these haplotypes segregated over several generations with ATD only (either clinical or subclinical), suggesting that in such families, ATD was a marker for a susceptibility to IDDM. In several families, an IDDM haplotype segregated with RA but not with ATD. This suggests that ATD- and RA-associated susceptibilities to IDDM may be biologically different and thus independently increase the risk of IDDM.

The relationship between hormonal pregnancy tests and congenital anomalies: a prospective study

In a prospective study of some 20,000 pregnancies in the Child Health and Development Studies in the San Francisco East Bay area, 226 gravidas were tested for pregnancy with estrogen/progestogen preparations. The two control groups were women who were tested for pregnancy by either a serum or urine test. There were no statistically differences (p greater than 0.05) in the rates of severe congenital anomalies between the hormone test group and the two control groups. The relative risks and the 95% confidence intervals were 1.01 (0.47-2.19) for the hormone/serum test comparison and 1.60 (0.60-4.18) for the hormone/urine test comparison.

Epidemiologic research in hypertension: a critical appraisal

Epidemiologic studies of blood pressure have been conducted for over twenty-five years, but the results of this research can only be described as modest. The basic epidemiologic and demographic description of blood pressure distributions in human populations remains problematic and psychosocial studies have not yielded clear and solid hypotheses pointing the way to future research. There is no doubt that blood pressures vary among and between population groups, and there seems little doubt that variations in life-style are associated with these differences. It is puzzling that we have failed to discern systematic and patterned relationships among these variables. It is suggested that a more useful approach to research in this field would be to distinguish factors that affect general susceptibility to becoming ill from those that initiate or maintain particular disease states.