CONGENITAL HEART DEFECT IN SIBS WITH DISCORDANT KARYOTYPES

Congenital heart defects (CHDs) are genetically heterogeneous, associa ted with a variety of genetic conditions. Familial aggregation of CHD in patients with and without Down syndrome is rare. We report on the o ccurrence of concordant CHD in three sets of sibs with discordant kary otypes. In the first family, atrioventricular canal (AVC) was diagnose d in a chromosomally normal child and in his brother with Down syndrom e. In the second family, AVC was associated with trisomy 21 in one sib and with trisomy 18 in the other, In the third family, tetralogy of F allot was present in one patient with Down syndrome and in his nonsynd romic sister. Although the genetic heterogeneity of Down and non-Down CHD is not disputed, a susceptibility to both euploid and aneuploid CH Ds could exist, and common predisposing factors could play a role in b oth conditions. (C) 1998 Wiley-Liss, Inc.