Conotruncal malformation complex: examples of possible monogenic inheritance.

Two families are described in which there is possible monogenic inheritance of congenital cardiac defects within the spectrum of faulty conotruncal septation (CTS). Evidence for a genetic control of conotruncal septation arises from genetic and embryologic studies of similar defects in the Keeshond dog model, the excess of sibship pairs with conotruncal septation defects in sibship pairs with congenital heart diseases, and previously reported pedigrees of families with multiple affected individuals with conotruncal septation defects. It is suggested that in the small number of cases of congenital cardiac defects in which there is a strong family history for CTS defects, a higher recurrence risk should be considered rather than the usual polygenic recurrence risk of 3% that is usually given in such situations.