Hereditary atrial septal defect. Update of a large kindred.

A large pedigree wherein members are predisposed to atrial septal defect (ASD) and associated cardiovascular anomalies has been studied. There were ten direct line relatives with ASD verified by cardiac catheterization and/or surgery and in one case by reliable medical history. The pedigree shows vertical transmission of ASD through four generations. Estimates of the genetic segregation ratio were near 50%, indicating that predisposition to ASD among family members was due to a deleterious autosomal dominant gene. Family members have also manifested other congenital heart anomalies, consistent with pleiotropic effects of the putative gene. Electrocardiograms in six ASD patients revealed an absence of prolonged P-R interval. In the light of prior studies showing prolonged P-R interval in familial ASD, we suggest the existence of at least two distinct hereditary varieties of ASD, one with and one without a prolonged P-R interval.