Extrahepatic Biliary Atresia in One Human Leukocyte Antigen Identical Twin

Extrahepatic biliary atresia is a neonatal disorder of unknown etiology that occurs approximately once in every 10,000 births. The absence of biliary atresia in stillborn infants suggests an acquired cause for this malformation. The nature of its occurrence in twins clearly would be helpful in gaining a better insight into the pathogenesis of biliary atresia. Only three reports of biliary atresia in twins have appeared in the literature. In two reports, biliary atresia occurred in only one of nonidentical twins.1,2 In one report, in the Russian literature, biliary atresia occurred in both twins of unknown zygosity.3 We now report the occurrence of operatively established extrahepatic biliary atresia in only one HLA identical twin.