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.