title: Discordant severe cranial defects in monozygous twins.
abstract: Three cases of monozygous male twins having exencephaly, anencephaly, and acephaly, with their cotwins being normal, are reported. Monozygosity of the twins was demonstrated by pathologic examination and in one case corroborated by blood group antigen testing. A constellation of abnormalities including adrenal hypoplasia in one of a pair of monozygous male twins with chorionic vascular anastomoses, together with the unusual racial background in each case, are in support of the possibility that environmental factors may play an etiologic role.
mesh_terms: D000293:Adolescent; D000328:Adult; D000757:Anencephaly / Q000473:pathology; D001344:Autopsy; D000013:Congenital Abnormalities / Q000473:pathology; D004200:Diseases in Twins; D005260:Female; D006801:Humans; D008297:Male; D011247:Pregnancy; D012886:Skull / Q000002:abnormalities* / Q000473:pathology; D014427:Twins; D014430:Twins, Monozygotic