Familial congenital hypoplasia of the thumb--report on a family.

Congenital hypoplasia of the thumb is not a rare condition in clinical practice, but a familial occurrence of this condition is exceedingly rare. We report a family with familial congenital hypoplasia of the thumb. In three generations, five members were proved to be affected and another two were presumed to be affected. To our surprise, a younger sister of the propositus had tetralogy of Fallot and triphalangeal thumbs on both hands.