Congenital biliary dilatation in dizygotic twins.

Congenital biliary dilatation (CBD) of different types was recently noted in dizygotic twins. Our cases suggest the possibility of hereditary involvement in CBD. On the other hand, CBD discordance in six sets of monozygotic twins has been reported, which would suggest that the occurrence of CBD is not compatible with single gene control, although environmental factors are plausible. To evaluate the genetic factors that may be implicated in CBD, it would be necessary to accumulate more familial cases and examine further studies on inheritance.