Familial Atrial Septal Defect with Prolonged Atrioventricular Conduction

SUMMARY 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 con-SECUNDUM ATRIAL SEPTAL DEFECT (ASD) is known to recur in some families suggesting a hereditary pre-disposition.'-" ' Recent twin studies and large population sur-veys of families with one or more affected members indicate that ASD usually does not conform to a simple dominant or recessive mode of inheritance but follows a multifactorial or polygenic pattern.'6-19 Thus, first degree relatives of an affected individual have a 35-40 times greater risk for AS