title: Biliary atresia in a twin.
abstract: The occurrence of biliary atresia in one of a pair of male twins is reported. The current concepts regarding the aetiology of biliary atresia are examined in relation to this case; and neither  the concept of a transplacental agent nor that of a genetic trigger mechanism seems probable. It is concluded that, as with many congenital defects, biliary atresia is probably the end-result of different aetiological factors, among which viruses and other agents may cross the placenta to cause it, whether or not there is a genetic predisposition in the individual fetus, or the biliary system may simply fail to develop.
mesh_terms: D001652:Bile Ducts / Q000002:abnormalities*; D004200:Diseases in Twins; D006801:Humans; D007223:Infant; D008297:Male