The inheritance of conotruncal malformations: a review and report of two siblings with tetralogy of Fallot with pulmonary atresia.

Congenital heart defects (CHD) are a group of structural abnormalities that in humans have a combined incidence of approximately 1%. It is estimated that 4-5% of CHD are associated with chromosome abnormalities, 1-2% are associated with single gene syndromes, 1-2% are due to known teratogens, with the rest presumably determined multifactorially. We report on a brother and sister with tetralogy of Fallot with pulmonary atresia, and review the inheritance of familial conotruncal anomalies. We feel the small number of family clusters and the rare instances of consanguinity in non-syndromal conotruncal defects are consistent with multifactorial determination. While it is prudent in counseling families with 2 or more individuals with conotruncal CHD to raise the possibility of single gene inheritance, we believe that current empiric recurrence risk estimates most accurately reflect their risks.