A case-control study of nonsyndromic oral clefts in Maryland.

PURPOSE: Isolated, nonsyndromic oral clefts cases (n = 171) and unaffected controls (n = 182) were used to identify both genetic and environmental risk factors. METHODS: Infants born in Maryland between 1992 to 1998 with an isolated, nonsyndromic oral cleft [cleft lip (CL), cleft lip and palate (CLP), or cleft palate (CP)] were recruited and exposure plus family history data were collected. Controls were unaffected infants. DNA was collected from all cases and their parents, plus controls. RESULTS: No statistically significant association was found between any of the following: maternal smoking, vitamin use, urinary tract infection, or recreational drug use in either univariate analysis or after adjusting for maternal age and education. More control mothers reported alcohol use during the critical time period of pregnancy (one month before conception through the first trimester) as compared to case mothers. There was a 10-fold increase in risk to siblings of cases as compared to siblings of controls. Markers at four candidate genes were examined: transforming growth factor alpha (TGF alpha), transforming growth factor beta 3 (TGF beta 3), MSX1, and BCL3. Only MSX1 showed significant differences in allele frequencies between CP cases and controls. MSX1 also showed significant evidence of linkage disequilibrium with a susceptibility gene controlling risk for CP. CONCLUSION: Most environmental risk factors examined here gave little evidence of association with risk to isolated, nonsyndromic oral clefts, although any alcohol consumption seemed protective. MSX1 showed evidence of linkage disequilibrium in both case-control and case-parent trio analysis.

Association between homeobox-containing gene MSX1 and the occurrence of limb deficiency.

Animal studies have suggested an important role for the homeobox-containing gene MSX1 in limb, oralfacial, and cardiac malformations. In this study of 516 Caucasians with isolated birth defects registered in the Maryland Birth Defects Reporting and Information System (BDRIS), we report an association between a dinucleotide repeat polymorphism in MSX1 and isolated limb deficiency. Frequencies of rare alleles at the MSX1 locus are significantly higher among 34 infants with limb deficiency compared to 482 infants with other isolated birth defects (oral clefts, dislocation of hip, clubfoot, hypospadias, polydactyly, or syndactyly) (chi2 = 11.0, df = 3, P = 0.012). Infants carrying the rare alleles had a 4.81-fold higher risk of a limb deficiency when the mother reported smoking during pregnancy, compared to infants who are homozygous for the common allele and whose mother did not smoke. The significance of this apparent gene-environment interaction is attributed to infants with malformation of the lower limb. The statistical association and potential gene-environment interaction observed in this study (which was originally designed to investigate oral clefts) are compatible with results from animal studies involving the MSX1 gene, and suggests that further investigation into biological mechanisms is warranted.

Testing for interaction between maternal smoking and TGFA genotype among oral cleft cases born in Maryland 1992-1996.

OBJECTIVE: Infants born in Maryland between June 1992 and June 1996 were used in a case-control study of nonsyndromic oral clefts to test for effects of maternal smoking and a polymorphic genetic marker at the transforming growth factor alpha (TGFA) locus, both of which have been reported to be risk factors for these common birth defects. DESIGN AND SETTING: Cases were infants with an oral cleft ascertained through three comprehensive treatment centers, with additional ascertainment through a registry of birth defects maintained by the Maryland Health Department. Controls were healthy infants. Medical history information on infants and mothers were collected, along with DNA samples. PATIENTS, PARTICIPANTS: Among 286 cases contacted (72% ascertainment), there were 192 nonsyndromic isolated oral clefts (106 M; 86 F) available for this case-control study. MAIN OUTCOME MEASURES: The largest group of 149 Caucasian nonsyndromic cases and 86 controls was used to test for association with maternal smoking and genotype at the Taq1 polymorphism in TGFA. RESULTS: While this modest sample had limited statistical power to detect gene-environment interaction, there was a significant marginal increase in risk of having an oral cleft if the mother smoked (odds ratio = 1.75, 95% CI = 1.01 to 3.02). We could not demonstrate statistical interaction between maternal smoking and TGFA genotype in this study, however, and the observed increase in the C2 allele among cases was not statistically significant. CONCLUSIONS: We could not confirm either the reported association between oral clefts and TGFA genotype or its interaction with maternal smoking. However, these data do show an increased risk if the mother smoked during pregnancy, and this effect was greatest among infants with a bilateral cleft and no close family history of clefts.

Guidelines for the retention, storage, and use of residual dried blood spot samples after newborn screening analysis: statement of the Council of Regional Networks for Genetic Services.

These guidelines provide scientific information for policy development by state health departments considering appropriate use of newborn screening specimens after screening tests are finished. Information was collected, debated, and formulated into a policy statement by the Newborn Screening Committee of the Council of Regional Networks for Genetic Services (CORN), a federally funded national consortium of representatives from 10 regional genetics networks. Newborn screening programs vary widely in approaches and policies concerning residual dried blood spot samples (DBS) collected for newborn screening. Recognition of the epidemiological utility of DBS samples for HIV seroprevalence surveys and a growing interest in DBSs for DNA analysis has intensified consideration of issues regarding retention, storage, and use of residual DBS samples. Potentially these samples provide a genetic material "bank" for all newborns nationwide. Their values as a resource for other uses has already been recognized by scientists, administrators, and judicial officials. Programs should promulgate rules for retention and use of residual newborn screening DBS samples based on scientifically valid information. Banking of newborn samples as sources of genetic material should be considered in light of potential benefit or harm to society.

Chorionic villus sampling and transverse digital deficiencies: evidence for anatomic and gestational-age specificity of the digital deficiencies in two studies.

Several but not all studies indicate that chorionic villus sampling (CVS) is associated with an increased risk for transverse limb deficiencies, including digital deficiencies. It has been suggested that variations in results regarding the transverse digital deficiencies (TDDs) may be due to the use of different classification criteria. We present the combined analysis of two case-control studies, the U.S. Multistate CVS (US) study and the Italian Multicentric Birth Defects (IP-IMC) study, using two different definitions of TDDs. We compared the frequency of CVS exposure in control infants with that among those infants with any number of affected digits (any TDD), and those with all five digits of at least one limb affected (extensive TDDs). The estimated relative risk (RR) for any TDD following CVS was 10.6 (IPIMC) and 6.6 (US). For the extensive TDDs, the RR was 30.5 (IPIMC) and 10.7 (US). In both studies, extensive TDDs were less than 25% of all TDDs. Compared to all TDDs, extensive TDDs were more likely to occur after CVS performed earlier in the first trimester (before 10-11 weeks' gestation). These findings suggest a relationship between the timing of CVS and the severity of TDDs; indicate that using a restrictive definition of TDDs (all five digits affected) may limit the ability to evaluate the association between CVS and TDDs in populations in whom CVS is usually performed at or after 10 weeks' gestation; and highlight the necessity to consider gestational age in any evaluation of the relative risk for limb deficiencies associated with CVS.

Association study of transforming growth factor alpha (TGF alpha) TaqI polymorphism and oral clefts: indication of gene-environment interaction in a population-based sample of infants with birth defects.

In this study of infants with isolated birth defects, 69 cleft palate only cases, 114 cleft lip with or without cleft palate cases, and 284 controls with noncleft birth defects (all born in Maryland between 1984 and 1992) were examined to test for associations among maternal exposures, genetic markers, and oral clefts. A significantly higher frequency of positive family history of birth defects among both groups of oral cleft cases compared with controls was seen in these data. While there was a modest increase in the less common C2 allele at the TaqI site in the transforming growth factor alpha (TGF alpha) locus among cleft palate only infants compared with the birth defect controls, the association appeared to reflect an underlying interaction between maternal smoking and infant genotype. This apparent gene-environment interaction was also found among those reporting no family history of any birth defect. Infants carrying the rarer C2 allele who were exposed to maternal smoking of 10 or fewer cigarettes per day showed a 6.16-fold increase in risk for cleft palate only (95% confidence interval 1.09-34.7), while similar infants whose mothers smoked more than 10 cigarettes per day showed an 8.69-fold higher risk (95% confidence interval 1.57-47.8). However, the dose-response relation was not significant.

HIV antibody seroprevalence among childbearing women surveyed in Maryland.

Because blood specimens from newborns reflect the antibody status of the mother, seroprevalence rates among childbearing women are obtainable from analysis of the specimens. A blinded survey of human immunodeficiency virus (HIV) antibody seroprevalence among childbearing women was conducted in Maryland. The survey used 31,273 dried filter paper blood spot specimens obtained from newborns screened for hereditary disorders. Overall, 99 specimens were positive on two enzyme-linked immunoassays and on Western blot, providing a seroprevalence rate of 0.32 percent. The rate for child-bearing women residing within the City of Baltimore, 0.7 percent, was significantly higher than the rate for those residing elsewhere in Maryland, 0.1 percent. The statewide rate for nonwhite women, 0.8 percent, was higher than for white women, 0.007 percent. No statistically significant associations were found with residence in an inner city area, as opposed to residence in other areas of the city; birth weight group; reported health of the infant; or the infant having received a transfusion.

Characteristics influencing informed consent on a congenital malformations registry.

Maryland law requires that all babies born with "sentinel birth defects" be reported to the State Department of Health, but mothers may deny consent for further contact. Consent was not strongly related to maternal age, race, or self-reported data on exposures, smoking, and drugs but was much less likely if the infant was dead. Selection bias in congenital malformations research may lead to underrepresentation of lethal defects, but self-reported data appear to be unbiased.

Residential mobility during pregnancy: implications for environmental teratogenesis.

Although most teratogens are suspected to act early in the first trimester of pregnancy, birth defects monitoring programs and etiologic studies usually use residence at birth as a proxy measure for residence in the first trimester in searching for environmental teratogens. Because of the high mobility of the U.S. population, residence misclassification can potentially alter inferences concerning environmental teratogens. To evaluate this potential bias, data from the population-based Maryland Birth Defects Reporting and Information System were analyzed. In 1984, the system ascertained 295 infants with one or more of 12 sentinel defects. Of these cases, 59 (20%) mothers reported they have changed address between the time of conception and the time of birth, and 22 have moved to a different county. The residential mobility rate varied by demographic variables and was highest among white women, in the age group 20-24 years. If residence at birth is used as a screening test for residence at conception, it can be shown that in the presence of an environmental teratogenic exposure, misclassification of exposure increases with increasing mobility rate, and population exposure frequency. Such misclassification tends to weaken associations between residence and birth defects and may lead to missing environmental teratogens. This analysis emphasizes the need to use residence information early in pregnancy rather than exclusively at birth.

Maternal cigarette smoking and oral clefts: a population-based study.

Analyses of 1984 data from the Maryland Birth Defects Reporting and Information System indicate that mothers of infants with oral clefts (cleft lip with or without cleft palate; and cleft palate) smoked more during pregnancy than mothers of infants with other defects (odds ratio OR of 2.56 and 2.39, respectively). There was a dose-response relation between the daily amount smoked and the risk of clefting. Adjustment for available confounding variables did not account for the association between smoking and oral clefts.

Inherited X-chromosome inverted tandem duplication in a male traced to a grandparental mitotic error.

A male infant was referred for cytogenetic evaluation because of dysmorphic features and developmental delay. In both lymphocytes and skin fibroblasts, a modal number of 46 chromosomes was obtained with an obvious elongation of the long arm of the X chromosome (Xq+). Studies of seven members in 3 generations of this family showed that the proband's mother, sister, and maternal grandmother were phenotypically normal carriers of this abnormal X chromosome. High resolution GTG- and RBG-banding defined the extra chromatin material as an inverted duplication of Xq21----Xq24. This was supported by an approximate twofold increase in alpha-galactosidase A activity, localized to Xq21----q24, observed in the proband's lymphocytes and fibroblasts. BrdU-incorporation studies of the mother's lymphocytes showed the abnormal X to be late replicating in all 100 cells studied and normal alpha-galactosidase A levels. Cytogenetic analysis of the maternal grandmother revealed cytogenetic mosaicism with one cell line containing the abnormal X (37%), and the other, a normal female karyotype (63%). This family is instructive since: (1) it represents only the second case of a dysmorphic male demonstrating a confirmed interstitial partial Xq duplication, and (2) the origin of this familial structural rearrangement has been traced to a grandparental mitotic error.

Deletions of proximal 15q and non-classical Prader-Willi syndrome phenotypes.

A deletion of the long arm of chromosome 15 (usually involving bands 15q11-q12) has been seen in approximately 50% of Prader-Willi syndrome (PWS) patients [Ledbetter et al, 1982]. However, 14 patients with non-PWS (or atypical PWS) phenotype with 15q deletion indicate great clinical variability. A deletion was found in a propositus with a de novo translocation [45,XY, -15, -22, +rec(15;22) (22pter----22q13.2::15q14----15qter)], who had anomalies not normally observed in PWS patients. Activities of several enzymes mapped to the involved chromosomes were studied in the patient and control individuals. A 50% decrease in the level of arylsulfatase-A confirmed a small deletion in 22q(22q13.2----qter), and additional studies localized more precisely the loci for alpha-mannosidase (cytoplasmic) and beta-galactosidase.

A complex rearrangement, including a deleted 8q, in a case of Langer-Giedion syndrome.

A 10-month-old infant with failure to thrive, delayed development, mild dysmorphia, cardiac anomalies, and cryptorchidism was referred for cytogenetic evaluation. Routine GTG-banded analysis revealed a modal number of 46 chromosomes, which contained an obvious complex rearrangement involving chromosomes 1, 8, and 14. Parental chromosomes were normal. Following high resolution techniques, this de novo rearrangement demonstrated an intraband deletion and was designated as [46,XY,t(1;8;14)(1pter----1p13.1::14q12----14pter++ +;1qter----1p13.1::8q24.13----8qter; 14qter----14q12::8p23.3----8q24.11:)]. Although deletions have been implicated as possibly responsible for abnormal phenotypes in patients with de novo "balanced rearrangements", in most cases, they could not be demonstrated. The present case is only the second instance documenting a subtle intraband deletion in association with a complex translocation. Fourteen of the reported 18 patients with an 8q deletion (including this infant) have Langer-Giedion syndrome, suggesting an etiologic relationship. However, the same deletion is not present in all cases.

Hydrops fetalis associated with Gaucher disease.

The rare association of hydrops fetalis with acute neuropathic Gaucher disease, diagnosed at autopsy, is described. Mechanisms for the fetal edema in this case are discussed. Unusual medial calcification of the aorta was present; and although its etiology is unknown, a possible relationship to Gaucher disease is suggested.

Duplication of chromosome 10p: confirmation of regional assignments of platelet-type phosphofructokinase.

A proband, clinically thought to have trisomy 10p, was found to have an inverted duplication of 10p [46, XY, inv dup(10)(qter----p15.3::p15.3----p 11.1:)]. The phenotypic findings and cytogenetic observations were supported by relevant biochemical studies. The activity of phosphofructokinase (platelet-type; PFKP), previously localized to 10p, and hexokinase-I (HKI), putatively on 10p, demonstrated 153% and 149% of control activity in the proband's fibroblasts. These gene-dosage effects confirmed the clinical and cytogenetic observations as well as the localization of HKI to 10p. Additionally, phosphofructokinase (PFK) and hexokinase (HK), which are control points in the glycolytic pathway, were shown to be syntenic.

Brief clinical report: cebocephaly-holoprosencephaly in a newborn girl with a terminal 7q deletion [46,XX,del(7)(pter leads to q32:)].

Cytogenetic study of a day-old infant showed a terminal del(7q): 46,XX,del(7)(pter leads to q32:). This infant had cebocephaly with holoprosencephaly. These clinical findings are atypical for the 7q - syndrome, in which patients usually have growth and mental retardation with few facial abnormalities.