title: Congenital dermatoglyphic malformations and psychosis: a twin study.
abstract: 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.
  
  
  METHODS
  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.
authors.affiliation: Laboratori d'Antropologia, Facultat de Biologia, Universitat de Barcelona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Rosa
authors.forename: L
authors.initials: L
authors.lastname: Fañanas
authors.forename: H S
authors.initials: HS
authors.lastname: Bracha
authors.forename: E F
authors.initials: EF
authors.lastname: Torrey
authors.forename: J
authors.initials: J
authors.lastname: van Os
mesh_terms: D003431:Cross-Cultural Comparison; D003878:Dermatoglyphics / Q000145:classification*; D004200:Diseases in Twins / Q000175:diagnosis* / Q000235:genetics*; D005819:Genetic Markers; D020022:Genetic Predisposition to Disease; D006801:Humans; D011618:Psychotic Disorders / Q000175:diagnosis* / Q000235:genetics*; D012307:Risk Factors; D012559:Schizophrenia / Q000175:diagnosis / Q000235:genetics; D014429:Twins, Dizygotic / Q000235:genetics; D014430:Twins, Monozygotic / Q000235:genetics; D006113:United Kingdom; D014481:United States
chemical_list: D005819:Genetic Markers