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Cardiovascular malformations (CVM) are the most common birth defects and carry significant and lifelong personal and societal costs. Research into genetic and environmental risk factors is therefore critical in identifying clues to causation and prevention. The purpose of this study was to investigate patterns of familial aggregation in CVM, specifically among infants with left-sided obstructive heart defects. We ascertained families of probands with hypoplastic left heart (HLH: N = 38), coarctation of the aorta (CoA: N = 46), and d-transposition of the great arteries (dTGA: N = 22). First degree relatives had clinical examinations and echocardiograms; all other relatives had detailed reviews of medical records. A total of 2,694 relatives were included in the study: 379 1st degree, 986 2nd degree, and 1,329 3rd degree. Mean nuclear family size and sibship size were similar among the groups. CVM were detected more frequently in 1st degree relatives of probands with HLH (19.3%) or CoA (9.4%) than among dTGA families (2.7%). The proportions of affected 2nd degree relatives were similar across groups (

Background: Coarctation of the aorta (CoA) is a congenital cardiovascular malformation (CCVM) sometimes associated with ventricular septal defect (VSD). Although the phenotypic association is well documented, little research exists on the epidemiological features distinguishing CoA with and without VSD., Methods: The Baltimore-Washington Infant Study (1981-1989), a population-based study of CCVM, evaluated 126 infants with "pure" CoA (free of associated cardiac defects) and 67 infants with CoA and VSD (COA/VSD) in comparison to 3,572 controls., Results: The proportion of infants with associated extracardiac anomalies was greater among CoA/VSD than among pure CoA (31% versus 11%). Infants with CoA/VSD were twice as likely as those with pure CoA to be born small for gestational age (23% versus 12%, respectively, compared with 6% of controls). All-cause mortality during the first year of life was higher in CoA/VSD than in pure CoA (21% vs. 7%). Multiple logistic regression models revealed that family history of CCVM was associated with pure CoA (adjusted case-control odds ratio [OR] = 4.6; 99% confidence interval [CI] = 1.5-13.9) and with CoA/VSD (OR = 5.9, CI = 1.2-23.5); maternal history of organic solvent exposures early in pregnancy was also associated with pure CoA (OR = 3.2, CI = 1.0-10.2) and with CoA/VSD (OR = 3.7, CI 0.9-14.9). Additional risk factors, including maternal epilepsy (OR = 5.3, CI = 0.9-30.6), and use of macrodantin (OR = 6.7, CI = 1.4-31.8) were associated only with pure CoA., Conclusions: These findings highlight possible genetic and environmental differences between pure CoA and CoA/VSD and may stimulate further investigations of the etiology of CoA., (Copyright 2001 Wiley-Liss, Inc.)

Gonadal (ovarian) dysgenesis with normal chromosomes (46,XX) clearly is a heterogeneous condition. In some forms, the defect is restricted to the gonads, whereas other affected females show neurosensory hearing loss (Perrault syndrome). In another form, brothers may have germ cell aplasia [Granat et al., Fertil Steril 1983; 40:215-219]. Nongenetic causes exist as well. To elucidate the proportion of XX gonadal (ovarian) dysgenesis due to autosomal recessive genes, we analyzed published (N = 17) and unpublished (N = 8) families having at least two female offspring. Analysis was restricted to cases in whom ovarian failure was documented by the presence of streak ovaries (published cases) or elevated gonadotropins (unpublished cases). We reasoned that the closer to that segregation ratio expected for an autosomal recessive trait (0.25), the lower the frequency of nongenetic forms. Segregation analysis utilized standard correction for single ascertainment, with only females included in the preliminary analysis. The segregation ratio estimate was 0.16. Our results suggest that many 46,XX females with gonadal (ovarian) dysgenesis represent a disorder segregating as an autosomal recessive trait, placing sisters of these cases at a 25% risk for this disorder.

Ebstein's anomaly is a specific structural deformity of the tricuspid valve, and its rarity has hampered etiologic evaluation. Cases of Ebstein's anomaly registered in the Baltimore Washington Infant Study (BWIS), a regional case-control study of cardiovascular malformations (CVM) in infancy, are reviewed. Between 1981 and 1989 a total of 4,390 CVM cases, including 47 Ebstein cases, and 3,572 controls were registered. The prevalence of Ebstein's anomaly was 5.2 per 100,000 livebirths. Additional cardiac anomalies were present in 38.3% of Ebstein cases. Non-cardiac malformations were present in 19.1% of Ebstein cases vs. 25.5% of other CVM, and 1.7% of controls. Case-fatality by 1 year of age was 23.4% in Ebstein vs. 18.1% in other CVM. Interviews of parents of Ebstein cases, other CVM, and controls (n = 44, 3,335, and 3,572, respectively) elicited information on family history of malformations, maternal illnesses, reproductive history, therapeutic drugs, parental lifestyle, and environmental exposures during the periconceptional period. Case-control analyses suggest genetic, reproductive, and environmental risk factors: twins [odds ratio (OR) 8.2, 95% confidence interval (CI) 2.6-25.3]; family history of CVM (OR 6.4, 95% CI 1.8-22.2); white race (OR 2.9 with non-whites as reference, 95% CI 1.2-7.0); previous miscarriages (OR 2.0, 95% CI 1.2-3.3); maternal exposure to benzodiazepines (OR 5.4, 95% CI 1.5-19.1); and varnishing (OR 3.4, 95% CI 1.3-9.1). Additional multicenter investigations are warranted to elucidate the role of genetic, reproductive, and environmental factors in the etiology of this anomaly.

Previous population studies of hearing loss have been limited to children with moderate to profound impairment, and have reported that heritability accounts for at least 50% of congenital or early-onset cases. The present study was designed to assess genetic factors associated with late-onset hearing impairment in an adult population. A brief family history and audiologic questionnaire was sent to approximately 11,200 members of the consumer organization, Self Help for the Hard of Hearing, Inc., and 4,039 questionnaires were returned. All respondents reported having at least one previous audiologic exam. Reported data were verified against audiograms when available. Regardless of the reported causes, 49% of early-onset cases (< or = 20 years of age) had one or two parent(s) with some form of hearing loss compared with 62% in later-onset cases. As expected, mean age at onset was substantially younger for cases with positive family histories than cases with negative family histories. Results from nuclear segregation analysis showed that fully recessive and dominant models failed to explain the early- or late-onset hearing loss data. In this nationwide survey, the large proportion of cases with positive family histories clearly indicates the importance of genetic factors in adult-onset forms of hearing loss. Comparison with younger-onset cases will permit further delineation of differences in inheritance patterns. This study should identify more homogeneous groups of adult-onset families for further genetic study, and provide empiric information for use in genetic counselling.

This brief review has described historic highlights of etiologic knowledge, current concepts in the categorization of cardiovascular anomalies based upon ongoing advances in teratology, and epidemiologic evaluations of biologic and xenobiotic risk factors with emphasis on the teratogenic roles of maternal diabetes, hyperphenylalaninemia, and parental exposures to alcohol, drugs, solvents, pesticides, lead, and other toxic substances. Evidence is presented for a strong genetic basis of cardiovascular maldevelopment requiring further studies to define at-risk families. Counseling and personal and societal preventive interventions may reduce the occurrence of some forms of CHD.

Linkage analysis is an important and clinically applicable method of predicting risk for genetic disorders and traits. When a gene cannot be detected directly, evaluation of a closely linked marker may be used in risk assessment. This review of linkage analysis provides basic information and examples of the application of these methods in genetic counseling situations.

The isolated occurrence of endocardial cushion defect (ECD) has been suggested to differ from its occurrence within the context of a syndrome, with regard to the nature (complete or partial) of the defect and the associated cardiovascular malformations. Analysis of data derived from the Baltimore-Washington Infant Study of congenital cardiovascular malformations supports the observation that "syndromic" ECD tends to be of the complete atrioventricular canal type and is less frequently associated with left cardiac anomalies than the isolated form. However, each syndrome has a unique impact on the overall cardiovascular "phenotype", including the ECD. This is especially true for Down and Ivemark syndromes, which are most frequently associated with ECD, but also for other syndromes as well. It is also suggested that isolated ECD is specifically associated with gastrointestinal and urinary tract anomalies. However, in Down syndrome ECD appears to be a specific cardiovascular expression of the trisomic state that is unrelated to other noncardiac malformations. Additional information on the association of ECD with other less common genetic syndromes is needed in order to further investigate the possible genetic basis of this cardiac defect.

Early onset periodontitis is a group of familial diseases that are not yet clearly defined by etiologic mechanisms, although some risk factors have been recognized. The disorders include a localized form of juvenile periodontitis (JP), and a more generalized form (GP). In a family study, 39 sibships (116 individuals, aged 13-48) were evaluated for clinical indices, neutrophil chemotaxis, and serum antibodies to A. actinomycetemcomitans (Aa). Of 77 siblings, 41 were healthy at examination. In 14 sibships, all affected persons had JP; 14 other sibships had all affected individuals with GP; and 11 had at least one sib with each form. For probands with decreased chemotaxis, 71% of affected sibs and 36% of clinically healthy sibs had decreased chemotaxis. For Aa seropositive probands, 83% of affected siblings and 65% of currently healthy sibs were also seropositive. The associations of disease with these risk factors were stronger in JP-only sibships. Some affected sibs had neither risk factor, while many currently healthy sibs had 1 or both. While these 2 factors demonstrate population association with disease, neither fits the pattern expected within families to clearly suggest a causal mechanism. The assessment of within and among family variability remains the best approach for recognition of possible causal mechanisms and sources of heterogeneity.

Five cases of the Pentalogy of Cantrell (PC), ascertained through the Baltimore-Washington population-based study of infants with congenital cardiovascular malformations, represent a regional prevalence of 5.5/1 million liveborn infants for this disorder. Three of these patients had cleft lip with or without palate. Review of the reported literature of the Pentalogy of Cantrell and various combinations of the anomalies within the spectrum of this pentad suggests that the PC defines a specific midline ventral developmental field. Cleft lip with or without cleft palate and encephalocele tend to specifically associate with ventral midline anomalies within the spectrum of PC. These associations might either illustrate the previously observed tendency of specific occurrence of certain combinations of midline defects or represent defined subunits of the midline developmental field.

In total anomalous pulmonary venous return (TAPVR), the intrapulmonary venous plexus has failed to connect to the left atrium, so that the pulmonary veins drain into right atrial tributaries, frequently resulting in early postnatal circulatory distress. The Baltimore-Washington Infant Study (BWIS), a population-based exploratory case-control study of cardiovascular malformations (CVM), identified 41 cases of TAPVR during 1981-1987: 1.5% of all CVM (N = 2659), a regional prevalence of 6.8/100,000 live births. Of the TAPVR infants, 68% were diagnosed as neonates, 88% had surgery, and 51.2% were alive at 1 year of age. Noncardiac malformations were present in nine cases (22%); the male-female ratio was 0.78 (18.23). Compared with a control group representative of the birth cohort (N = 2,801), more TAPVR patients had low birthweight (less than 2,500 g: 16.2% vs. 6.9%, short gestational age (less than 38 weeks: 18.9% vs. 9.3%), and intrauterine growth retardation (IUGR) (26.8% vs. 5.8%). Sociodemographic findings were similar to those of controls, except that fewer TAPVR mothers received private pregnancy care (59.5% vs. 71.4%). Family history revealed no other TAPVR-affected members, but a significant linear trend of increased risk was found over the ordered malformation categories (familial noncardiac, cardiac, both). Bivariate analysis of TAPVR and exposure in life-style, hobbies, and work showed possible associations for exposure to lead (OR 2.9; 99% confidence interval [CI]: 1.2, 7.2), painting/paint stripping (OR 3.3; 99% CI: 1.3, 8.4), lead soldering (OR 13.3; 99% CI: 1.8, 99.2), and pesticides (OR 2.7; 99% CI: 1.2, 6.4). Multivariate analysis suggested an interaction between pesticide exposure and family history and, thus, a possible familial susceptibility to environmental teratogens. Although the number of TAPVR cases is small, this epidemiologic study identifies hypotheses that may be further explored in morphogenetic and epidemiology studies. Total anomalous pulmonary venous return (TAPVR) constitutes a well-defined clinical entity in which the pulmonary veins fail to enter the left atrium and instead drain into the right atrium or its systemic venous tributaries (Neill, '56; Rowe et al., '81). During intrauterine life, the malformation does not compromise the fetal circulation, since the pulmonary arterial resistance is high and the patent foramen ovale provides easy access of right atrial blood to the left side of the heart. At birth, however, the pulmonary vascular resistance begins to fall, and the presence of a severe hemodynamic disturbance becomes increasingly evident (Ferencz et al., '71).(ABSTRACT TRUNCATED AT 400 WORDS)

In a study of 1,703 pregnancies, adverse clinical outcomes associated with unexplained elevated maternal serum alpha-fetoprotein (MSAFP) included intrauterine growth retardation (IUGR), prematurity, IUGR and prematurity, prematurity without IUGR, spontaneous abortion, and stillbirth. These findings have significant implications for careful obstetrical management of patients with elevated MSAFP.

Mean birth weights were evaluated in infants with D-transposition of the great arteries, tetralogy of Fallot, endocardial cushion defect, hypoplastic left heart syndrome, pulmonary stenosis, aortic stenosis, coarctation of the aorta, ventricular septal defect, and atrial septal defect in a population-based case-control study of congenital cardiovascular malformations in residents of Maryland, Washington, D.C., and northern Virginia (1981-1987). Study subjects were liveborn singletons without extracardiac anomalies. After adjustment for potentially confounding maternal, gestational, and infant factors, significant birth weight deficits were found for infants with tetralogy of Fallot, endocardial cushion defect, hypoplastic left heart syndrome, pulmonary stenosis, coarctation of the aorta, ventricular septal defect, and atrial septal defect. After adjustment, infants with these malformations (except coarctation of the aorta and atrial septal defect) were also significantly more likely than were controls to have low birth weight for gestational age. These findings strengthen previous evidence that certain cardiovascular malformations and low birth weight may be causally related.

Nine cases of congenital cardiovascular malformations (CCVM) with associated unbalanced structural chromosomal abnormalities were ascertained in a population-based study of heart defects, constituting 0.4% of the 2,103 cases of CCVM in the Baltimore-Washington Infant Study (BWIS). This represents a four-fold increase over the general population rate. In an effort to determine possible phenotype/karyotype correlations, the literature was searched for cases with similar karyotypic abnormalities. This comparison of 223 literature cases of karyotypic abnormalities with nine similar cases ascertained by heart malformation has provided the opportunity to review cardiac defects reported in cases of structural abnormalities of chromosomes 1, 3, 7, 8, 9, 10, 11, 15, and 18. The most common cardiac malformation present in the chromosomal cases was ventricular septal defect (VSD) (39%); similarly VSD is the most common CCVM among children with heart defects, although it is the primary defect in only 20% of the BWIS cases. Among all heart defects in the BWIS, atrial septal defect (ASD) represents 5.5% of all cases, but in cases of 8p duplication, ASD is present in 41%. In addition, 40% of cases of 9p duplication had an ASD. Similarly, 35% of cases of 11q duplication had an ASD. While the suggestion of specific karyotype/phenotype association is premature, information on additional cases might clarify the possibility that genetic determinants related to septum formation may reside on chromosome 8, 9, and/or 11. The variety of chromosomal abnormalities in cases with ventricular septal defect indicates one type of genetic heterogeneity that may be involved in this very common heart defect.

Restriction fragment length polymorphisms (RFLPs) in the T cell receptor (TCR) alpha, beta, and gamma genes were analyzed in 61 scleroderma patients and 150 controls. An association was found between scleroderma and an 11.3-kb Pvu II fragment in the TCR gamma gene; this gene was found in 41.0% of the patients, compared with 21.7% of the controls (P less than 0.01, odds ratio = 2.50). There were no associations between scleroderma and the tested RFLPs in the TCR alpha or beta genes, and no RFLPs were found in the constant region of the TCR delta gene.

Sister-chromatid exchanges (SCE), both spontaneous and chemically-induced [bleomycin (BLM), mitomycin-C (MMC), streptonigrin (SN), and 4-nitroquinoline-1-oxide (4NQO)], were studied in the lymphocytes of 24 normal individuals on 2 or 3 different occasions, separated by periods of up to 2 years. For all BLM-induced SCEs, the variation in SCE frequency among the samples from a single individual was significantly greater than the variation between replicate cultures on a given day. These results raise questions concerning the validity of conclusions based on a single observation of chemically-induced SCEs.

Segregation distortion was observed in inheritance of progressive rod-cone degeneration (prcd) in a colony of Miniature Poodle dogs. Breeding results, from both retrospective records and prospectively planned matings, were classified into five mating types: (1) affected to affected, (2) homozygous normal sire to any dam, (3) heterozygous to heterozygous, (4) heterozygous sire to affected dam, and (5) affected sire to heterozygous dam. For all but the last category, results were in accord with mendelian expectations for autosomal-recessive inheritance. However, litters of mating type 5 had fewer affected pups (20/77) than expected. The observed segregation ratio for this mating type (0.26) was significantly (P less than 0.001) less than the expected (0.50). The segregation distortion could not be accounted for by either pre- or postnatal loss of affected pups, as litter size and litter survivability were uniform among litters of different mating types. Either the prcd locus, or a linked locus, would appear to influence either gametic or zygotic fitness in the heterozygous mother. Comparison is drawn to the inheritance of retinitis pigmentosa in humans, in which decreased segregation ratios are also recognized.

The Baltimore-Washington Infant Study, an epidemiologic investigation of congenital heart disease, searches for genetic and environmental risk factors. Among 2,102 infants with heart disease, 17.5% had a noncardiac abnormality of chromosomal or genetic origin, whereas among 2,328 control infants, only 0.7% had a genetic abnormality. Familial cardiovascular malformations encountered can be grouped into five distinct etiologic mechanisms. Single gene effects may be responsible for the specific histologic and biochemical changes in familial atrial septal defect with conduction disturbance and also in idiopathic ventricular hypertrophy. Left heart lesions showed familial concordance by the presumed morphogenetic mechanism of abnormal embryonic blood flow with phenotypes of varying severity. Pulmonary stenosis appeared with familial heritable disorders, as well as a partially concordant lesion with tetralogy of Fallot. Ventricular septal defect with transposition of the great arteries (one sibling pair) and with truncus arteriosus (two sibling pairs) indicate forme fruste expression of conotruncal defects. Endocardial cushion defect occurred with and without Down's syndrome in members of three families, suggesting inheritance of a defect affecting cellular migration. Heritable blood coagulopathies occurred in case families and not in control families. The associated of hemophilia and transposition, observed also by others, is extremely unlikely by chance and suggests genetic errors of endothelial cell function. The description of specific families from a population-based study emphasizes biologic questions on the nature of the inheritance of cardiovascular malformations.

Restriction fragment length polymorphisms (RFLPs) in types I and III procollagen genes were studied in 62 scleroderma patients and 138 healthy controls. Allelic frequencies were determined for each RFLP, and comparisons were made between the 2 populations, stratifying them by race when appropriate. No statistically significant differences were observed for the frequencies of any of the RFLPs studied.

A questionnaire survey characterized a sample of 670 probands with retinitis pigmentosa (RP) and allied disorders. Segregation analysis provided some evidence for a small proportion of sporadic cases and for decreased segregation ratios of the dominant and recessive genotypes, which could be attributed to delayed age of onset in some cases. The overall incidence of RP was indirectly calculated to be approximately 1 in 3,700, while the incidence of autosomal recessive RP, including at least two genocopies, was estimated to be about 1 in 4,450. Family data analysis included the calculation of the likelihood that each family represented autosomal recessive, autosomal dominant, and X-linked inheritance patterns. These likelihoods were then converted to relative probabilities and summed over the sample population to yield estimates of the proportions of the three Mendelian types. This large, heterogeneous sample indicated that approximately 84% of the cases in the United States may be autosomal recessive, while about 10% are dominant and 6% X-linked recessive.

The Baltimore-Washington Infant Study is a population-based case-control study that seeks to identify risk factors for cardiovascular malformations. Between 1981 and 1986, a total of 2102 infants with cardiovascular malformations were ascertained, among whom 271 (12.9%) also had a chromosome abnormality. Among 2328 random control subjects, only two had a chromosome abnormality. Down syndrome with cardiovascular malformations had a maternal age-adjusted regional prevalence of 4.33/10,000 for the white population and 3.70/10,000 for the nonwhite population. Endocardial cushion defect, the predominant cardiac abnormality in Down syndrome (60.1%), rarely occurred as an isolated cardiac lesion (2.8%). The absence of transpositions and the rarity of heterotaxias and of right- and left-sided obstructive lesions in trisomies indicate that there may be a genetic influence on specific embryologic mechanisms. Alimentary tract lesions were more common in Down syndrome than among euploid patients with heart disease and more severe than in control subjects. Urinary tract lesions also occurred in excess of the rate in control subjects. The coexistence of these major malformations with heart disease raises the possibility of incomplete expression of the VA(C)TER (vertebral, anal, cardiac, tracheal, esophageal renal) association. The selective association of chromosome abnormalities with certain cardiovascular defects is now beginning to be explained by reported embryologic studies on cellular characteristics. An explanation of the negative association with transposition and obstructive lesions requires further multidisciplinary studies on genetic and epigenetic factors.

Long-term lymphoid cell lines (LCL) derived from normal individuals, patients with ataxia telangiectasia (A-T), xeroderma pigmentosum (XP), and Fanconi anemia (FA) were exposed to various concentrations of 11 chemical clastogens. The agents were chosen to represent a variety of suggested modes of action. In contrast to all other genotypes, the FA lines demonstrated significant rates of spontaneous chromosomal breakage and showed hypersensitivity to all of the clastogens employed. Variability among lines within a genotype suggested individual responses to specific agents. Computation of "corrected values" to address the problem of baseline disparity removed some of the significant differences between the FA and other lines. Nonetheless, following correction, the FA genotype was still delineated by clastogens which are not DNA cross-linkers. The A-T lines were specifically identified by the induction of chromosome damage by bleomycin and neocarzinostatin.

Data from 28 families ascertained through a proband with juvenile periodontitis were used to test a series of Mendelian models of inheritance that included both autosomal and X-linked transmission. There was strong evidence of familial aggregation of this progressive dental disease, and the best-fitting model was an autosomal recessive model. Because of the rather limited age range for expression of the disease in this situation, simulations were done, in a model-choice analysis using samples of this size, to assess the chance of mistaking an autosomal dominant disease (with masking of the affected phenotype outside a specified age range) for an autosomal recessive disease. While the rate of Type II error was fairly high (40%) when competing models in these simulations were compared, these data suggest that it is reasonable to infer that juvenile periodontitis is an autosomal recessive disorder.

Clinical and laboratory data were compared in 72 patients with localized periodontitis (LP) and 103 patients with generalized periodontitis (GP). Significantly more LP than GP cases had decreased neutrophil chemotaxis (CTX), and were seropositive for Actinobacillus actinomycetemcomitans (Aa). Significantly, more GP cases were seropositive for Bacteroides gingivalis (Bg). All clinical indices were similar on affected teeth in LP and GP, but the attachment loss was greater on clinically unaffected teeth in GP when compared with LP. LP cases with CTX defects had a significantly lower mean age, were more often seropositive for Aa antibodies, and were more often female than LP patients with normal CTX. Significantly more GP cases with CTX defects were seropositive for Aa antibody. GP patients with normal CTX had a higher plaque index on both affected and unaffected teeth than did GP patients with a CTX defect. Our data suggest that chemotaxis and/or specific bacteria may be contributory, but not always necessary, factors in these disorders. The overlap in clinical and laboratory profiles of LP and GP continues to cloud the distinction of these early onset forms of periodontitis.

A sample of 437 reciprocal translocations was classified into three groups according to their method of ascertainment (Group I = couples with repeated abortions; Group II = karyotypically unbalanced carriers; Group III = balanced translocation heterozygotes). Statistical analysis showed that the distributions of chromosome breaks observed in the three groups could not be accounted for by chromosome arm length alone. In couples with repeated abortions, an excess of breaks in 7p, 17p, and 22q was found, whereas in the balanced translocation heterozygotes an excess of breaks was found only in 11q. An excess of breaks was found in arms 9p, 14p, 18p, 18q, 21q, and 22q in karyotypically unbalanced probands. A significant decrease of breaks in the medial chromosome regions was accompanied by a concomitant increase in the terminal regions in all groups. The three groups demonstrated different distributions of chromosome arm involvement in the observed translocations. Balanced translocation heterozygotes had the highest frequency of large (greater than the length of 4p) translocated segments and an excess in the frequency of large-large translocations, whereas karyotypically unbalanced probands had the highest frequency of small (shorter than 21q) translocations and an excess in the frequency of small-small translocations. For each type of chromosomal imbalance observed, the balanced translocation heterozygotes demonstrated the greatest potential imbalance and the karyotypically unbalanced probands the least.

The HLA-DR locus of the major histocompatibility complex encodes class II molecules which participate in immune responses through regulation of T cell interaction with antigen presenting cells. Previous association studies between HLA-DR antigens and the autoimmune disease, systemic sclerosis (or scleroderma), have yielded conflicting results. Some investigators have reported an association between this disease and HLA-DR1, while others have demonstrated an association with HLA-DR5. In this study, we used restriction fragment length polymorphisms in the HLA-DR locus to compare allelic frequencies of HLA-DR1 and HLA-DR5 in scleroderma patients with diffuse disease and healthy control subjects. No significant difference in the allelic frequency of either antigen was observed between the groups. These results suggest that HLA-DR1 and HLA-DR5 antigens are unlikely to contribute significantly to disease susceptibility in scleroderma.

Study of a large five-generation kindred from southern Maryland revealed that type III dentinogenesis imperfecta (DGI-III) and a localized form of juvenile periodontitis (JP) were both segregating as autosomal-dominant traits. Linkage analyses demonstrated that these were two distinct clinical entities, making this family the first documented instance of an autosomal-dominant form of JP. Since the locus for the more common form of dentinogenesis imperfecta (DGI-II) is on chromosome 4q [Ball et al, 1982], a linkage analysis of genetic and chromosomal markers on chromosome 4 was undertaken. The results suggested that the locus for the DGI-III subtype is located a similar distance from the Gc locus (theta = 0.12) as the distance previously observed between Gc and DGI-II loci (theta = 0.11) [Ball et al, 1982; Conneally et al, 1984]. Most likely the two DGI subtypes are determined by genes at closely linked loci, by allelic genes, or by the same gene with the variable expression in different families. In addition, close linkage between the Gc locus and that determining the autosomal-dominant form of JP was observed in this family (theta = 0.05). The known map of chromosome 4q and our analysis of the markers tested suggested the gene order to be 4cen----JP----Gc----DGI----MNS----qter with a large distance (at least 15 cM) between 4cen and JP.

Simulated data were generated under four etiologic mechanisms for each of 20 different pedigree structures drawn from a study of families ascertained through a proband with retinitis pigmentosa. These simulated data were then used to identify subgroups of pedigrees which best supported each of three genetic mechanisms (autosomal dominant, autosomal recessive, X-linked recessive with 10% penetrance of disease in heterozygous females) and a non-genetic, sporadic mechanism. Results of these studies show that pedigrees identified as supporting one genetic model in a 'model choice' approach tend to be etiologically homogeneous, but are not truly representative of all the phenotypic combinations possible under that mechanism. The problem of etiologic heterogeneity is most acute when dealing with pedigrees less than size 10. Pedigrees lumped under a non-genetic, sporadic mechanism are extremely heterogeneous and studies of the natural history of diseases where both genetic and non-genetic mechanisms may be operating (such as with retinitis pigmentosa) should avoid using this group of largely simplex pedigrees.

A regional case-control study of congenital cardiovascular malformations (CCVMs) searches for all live-born infants in the community in whom the cardiac diagnosis has been confirmed by echocardiography, cardiac catheterization, surgery, or autopsy. Their families are studied in comparison to those of a representative sample of resident live-born infants. Detailed descriptions of noncardiac abnormalities are obtained from physician reports and maternal interviews expanded by medical record and death certificate data. Among 1,494 cases and 1,572 controls, chromosomal abnormalities, syndromes, heritable disorders, and suspect syndromes occurred with an overwhelming excess in cases (chromosomes, P less than 10(-4); syndromes/heritable disorders, P less than .005). Abnormalities affecting chromosomes 13, 18, and 21 constituted 93% of the cytogenetic defects. Syndromes and heritable disorders were of 39 types. Nonsyndromic abnormalities were three times more frequent in cases than in controls (P less than .005). Case excesses occurred for central nervous system malformations, eye disorders, major abdominal wall defects, and abnormalities of the alimentary and urinary tracts. Severe anomalies frequent among cases were those which also occur in certain recognized syndromes, and it is suggested that paired combinations of cardiac and other midline anomalies may represent "formes frustes" of syndromes with similar though variable phenotypic expressions. Cleft lip and palate, inguinal hernia, and lower limb anomalies occurred with equal frequency, suggesting their association with CCVMs by chance alone.

Nettleship-Falls ocular albinism is an X-linked disorder characterized by variable degrees of impaired visual acuity, nystagmus, and macular hypoplasia in affected males and variable fundus pigmentation but normal acuities in females. Because of extreme variability in clinical manifestation, examination of family members may be necessary to confirm the diagnosis and is essential for genetic counseling purposes. This study reports the pedigree analysis and clinical findings in a large kindred from rural Virginia with 31 males reported to be affected among the 287 individuals in the pedigree. Clinical findings were quite variable, even within sibships, and some cases had been previously misdiagnosed, even in the presence of this remarkable family history. Linkage analysis in this family did not show the expected linkage with the Xg blood group. Examination of skin biopsies clearly indicated the cutaneous abnormality of giant pigment melanosomes (GPM) in both affected males and carrier females. Our use of light microscopy for detection of characteristic GPM may be easily employed as a carrier detection test, and therefore, provide the basis for accurate genetic counseling in families with ocular albinism.

The Usher Syndrome (US) refers to the combined neurosensory deficits of profound hearing impairment and retinitis pigmentosa. We have obtained information on 600 cases of deaf-blindness from the registry of the Helen Keller National Center for Deaf-Blind Youths and Adults (HKNC). Of these, 54% met the diagnostic criteria of US, although only 23.8% were so diagnosed. More extensive analysis of 189 Usher clients from HKNC showed an excess of males, some variability in audiograms, and wide ophthalmologic variation. Genetic analysis of 113 sibships showed a segregation ratio consistent with recessive inheritance. The Acadian population of Louisiana has a high frequency of US which contributes significantly to the deaf population of the state. Among 48 cases from the Louisiana School for the Deaf, there was an excess of males, more variability in audiograms than expected, and an increased segregation ratio in the 26 informative sibships. Estimates of prevalence obtained using registry data and statistics from Louisiana clearly suggest that the previous estimate of 2.4 per 100,000 is too low for the United States. Recognizing problems with ascertainment, our prevalence estimate of 4.4 per 100,000 is still considered quite conservative.

In a population-based study on congenital cardiovascular malformations (CCVM), the occurrence of heritable coagulopathies among case parents and not among controls raised the possibility of an etiologic association of CCVM with blood disorders. The literature was searched for evidence that such an association could be biologically plausible. Reported embryologic and clinical data provided confirmatory findings. The heart and blood arise from common angiogenic cells; endothelial cells, the first components of the primitive heart, synthesize coagulation factors; resultant osmotic alterations of embryonic fluids could alter early cardiac morphogenesis. Bleeding diatheses are common in cyanotic and acyanotic patients with CCVM and hemostatic disorders have been reported in some families. CCVM and blood disorders are joint components of several malformation syndromes. The hypothesis of an etiologic relationship between HBD and CCVM needs to be tested in multiple research areas. Future experimental studies should be based on current theories of cardiac morphogenesis to include investigations of embryonic blood in genetic blood disorders. Clinical studies should clarify hematologic alterations in CCVM probands and their families.

Genetic analysis of 457 patients with retinitis pigmentosa (RP) included categorisation of families by recognised mendelian pattern of inheritance and formal segregation analysis of all informative sibships. Of the 368 probands a surprisingly high 18% (68) had significant congenital loss of hearing and were diagnosed as having Usher syndrome. The RP probands were categorised as: 21.7% autosomal dominant, 9.0% X-linked, 16.0% autosomal recessive, 3.3% genetic type uncertain, and 50.0% simplex. Segregation analysis reflected this high proportion of simplex cases, accounting for reduced penetrance in dominant families; only 20% remain classified as sporadic (possibly nongenetic). In the matings between normal persons estimates of the segregation ratio also indicate lower values than expected. Unlike in RP sibship, segregation in the Usher syndrome is consistent with the hypothesis of recessive inheritance. Therefore RP with significant hearing loss segregates as expected, while even if a proband is classified as a dominant or recessive the recurrence risk for the RP phenotype may be below mendelian expectation.