Congenital Dermatoglyphic Malformations and Psychosis: A Twin Study

OBJECTIVE: In a previous twin study, congenital dermatoglyphic abnormalities, such as ridge dissociations and abnormalities of palmar flexion creases, were more prevalent in twins with psychotic and related disorders than in comparison twins. This study was an attempt to replicate that finding in an independent study group. METHOD: Ridge dissociations and abnormal palmar flexion creases were assessed in monozygotic pairs concordant (19 pairs) and discordant (31 pairs) for psychosis and related disorders. RESULTS: The presence of either ridge dissociations or abnormal palmar flexion creases was higher in the combined group of affected concordant and discordant twins (37.7%), than in the nonaffected discordant twins (20.0%; odds ratio=2.4). In the discordant pairs, the presence of either abnormality was strongly associated with psychotic disorder (odds ratio=3.0). CONCLUSIONS: Factors affecting early fetal development may increase the risk for psychotic disorder. Differential exposure to such early risk factors may contribute to twin discordance for psychotic disorder.