Genetics of atrial septal defect

NKX2-5 molecular screening and assessment of variant rate and risk factors of secundum atrial septal defect in a Moroccan population

OBJECTIVE

Secundum atrial septal defect (ASDII) has multifactorial etiology that is combination of environmental (e.g., mother's exposure to toxicity, ethnicity) and genetic causes. Aim of the present study was to screen a Moroccan population with ASDII for NKX2-5 variants and to assess risk factors that may contribute to emergence of the disorder.

METHODS

Thirty-two non-syndromic ASDII patients were screened for NKX2-5 variants using direct sequencing of polymerase chain reactionamplified coding regions. Risk factor rates were compared to general population and assessed using Fisher's exact and chi-square tests. In this retrospective study, criteria of exclusion were suggestive or confirmed syndrome association.

RESULTS

Three heterozygous variants were detected in 4 patients. NKX2-5 variant rate in present cohort is estimated to be about 9.4%. Two prominent risk factors in the Moroccan population were highlighted: consanguinity, rate of which was significantly high at 30.8%, and previous maternal miscarriage or sibling sudden death, observed in 34.6% of cohort.

CONCLUSION

Impact of identified variants was discussed and possible disease-predisposing effect is suggested. Findings indicate that ASD may be favored by consanguineous marriage and that NKX2-5 variant rate in ASD patients may be affected by ethnicity. High level of maternal miscarriage and sibling sudden death suggests potential non-sporadic nature as result of putative genetic defect.

The familial form of atrial septal defect

BACKGROUND

The secundum atrial septal defect accounts for 10% of congenital heart disease. Familial occurrence is rare and may present as an isolated lesion or with conduction and skeletal abnormalities. Predisposing genes were described.

OBJECTIVES

To evaluate familial defect's prevalence and associated anomalies and assess the yield of screening.

METHODS

Family history, physical, electrocardiographic and echocardiographic evaluation of 286 ASD patients and families regarding heart disease, conduction and skeletal anomalies were performed.

RESULTS

Eleven new families with familial defects were identified yielding 28 patients. The rate of transmission was 40-100%, suggestive of autosomal dominant inheritance. Parents were healthy in four families with multiple offspring with ASDs. Two families had ASDs with atrioventricular conduction abnormalities in five of six subjects, not requiring pacing. One subject had skeletal malformation. Ten patients had surgery, 12 had transcatheter ASD closure and six await treatment.

CONCLUSIONS

In view of the high prevalence of familial occurrence of secundum ASD (10% of all ASD patients), we recommend screening all first degree relatives of ASD patients for cardiac, conduction and skeletal anomalies. Although a routine genetic investigation is not yet available, genetic patterns of inheritance may be compatible with autosomal dominant inheritance. Healthy parents of affected offspring may suggest a variable gene penetrance or past spontaneous ASD closure. Conduction anomalies may be present or may develop throughout life, and thus should be periodically screened for.

Further delineation of the Opitz G/BBB syndrome: report of an infant with complex congenital heart disease and bladder exstrophy, and review of the literature

The combination of complex congenital heart disease (double outlet right ventricle with pulmonary atresia, malalignment ventriculoseptal defect, right-sided aortic arch with left ductus arteriosus) and bladder exstrophy occurred in an infant with Opitz syndrome. Neither of these defects has previously been reported in association with Opitz syndrome. These malformations, which are midline defects, further characterize this syndrome as an impairment in midline development. The spectrum of congenital heart disease and genitourinary anomalies seen in Opitz syndrome is reviewed.

Male-to-male transmission of the hypertelorism-hypospadias (BBB) syndrome

A boy and his father with the hypertelorism-hypospadias (BBB) syndrome are described. This example of male-to-male transmission is evidence that the BBB syndrome is not due to an X-linked gene.

Dermatoglyphs in congenital heart disease

The palmar dermatoglyphs of 800 patients with anatomically proven congenital heart disease were compared with prints from 1000 controls. A review of the previous studies revealed major technical deficiencies, and the present study failed to confirm most of the previously reported positive findings. An overall increase in the incidence of hypothenar patterns was found, probably explaining the previous suggestion of increased atd angle in congenital heart disease. A large number of statistical comparisons inevitably produced a few 'significant' results, most of which were inconsistent in various ways. Two percent of cases were found to have rare epidermal ridge malformation, ridge dissociation. The nature of the relationship between this and congenital heart disease is obscure. Claims that there are diagnostically useful dermatoglyphic changes in congenital heart disease can be disregarded.

Risks to the offspring of patients with some common congenital heart defects

The families of 424 adult index patients with ventricular septal defect, right ventricular outflow tract obstruction, or combinations of these two abnormalities, were visited and interviewed, and whenever possible the children of index patients were examined clinically. Congenital heart defects were present in 9 of 308 children, 8 of 899 sibs, 4 of 840 parents, and 4 of 731 nephews and nieces of the index patients. The last three figures are likely to be underestimates owing to the design of the study. Comparison of pairs of affected relatives suggests that the group of lesions studied may have genetic determinants in common.

Studies of malformation syndromes of man VB: the hypertelorism-hypospadias (BBB) syndrome. Case report and review

We describe a boy with the hypertelorism-hypospadias (BBB) syndrome. His mother and his maternal grandmother showed minor manifestations suggestive of the syndrome. The BBB syndrome is a syndrome of multiple congenital anomalies with mental retardation due a segregating mendelian mutation, either X-linked or autosomal. This paper reviews the literature on the subject and emphasizes the problem of identifying females at high risk of transmitting the condition.

Familial atrial septal defect with prolonged atrioventricular conduction

This report describes a family with frequent recurrence of congenital heart disease in multiple generations. Eight members had atrial septal defect (ASD) of the fossa ovalis type and seven members had other forms of congenital heart disease. One branch of the pedigree showed a predominance of ASD with prolonged atrioventricular (A-V) conduction and initially suggested an autosomal dominant gene effect. A variety of other forms of congenital heart disease were found in several first degree relatives of those with ASD as well as in more distant relatives. The variability of congenital heart disease in this pedigree is compatible with the polygenic mode of inheritance. Definition of the inheritability of congenital heart disease in a specific family has important consequences in the determination of the recurrence risks for all family members.

Genetics of patent ductus arteriosus

A genetic study of 119 correlative cases of patent ductus arteriosus has been performed. The isolated cases showed female predominance, but there was a three times higher risk for the sibs of male cases, suggesting a multifactorial causative mechanism. Dermatoglyphs presented an excess of arches in male, and a tendency to distal axial triradius in female. There were 15 cases belonging to polymalformative syndromes, such as mongolism, Turner, Noonan, Holt-Oram, Lewis and rubella embryopathy.