title: Twin concordance for DSM-III-R schizophrenia.
abstract: The monozygotic (MZ)/dizygotic (DZ) concordance rates for schizophrenia and the relationship between schizophrenia and schizophrenic spectrum disorders were studied in a sample of 31 MZ and 28 DZ schizophrenic probands and their co-twins. All subjects were personally interviewed with structured diagnostic instruments and classified according to DSM-III-R criteria. The concordance rates of 48% for MZ twins and 4% for DZ twins indicate a genetic transmission of DSM-III-R schizophrenia. In addition to the schizophrenic co-twins, 3 MZ co-twins had a noneffective psychotic disorder, thus supporting the hypothesis that genes are involved in the development of Axis I schizophrenic spectrum disorders. Schizotypal and paranoid personality disorders were observed in both MZ and DZ co-twins. These disorders may be familially related to schizophrenia, but a genetic relationship was not confirmed for the Axis II spectrum disorders. A substantial number of MZ co-twins of schizophrenic probands had no mental disorder.
authors.affiliation: Department of Psychiatry, University of Oslo, Norway.
authors.forename: S
authors.initials: S
authors.lastname: Onstad
authors.forename: I
authors.initials: I
authors.lastname: Skre
authors.forename: S
authors.initials: S
authors.lastname: Torgersen
authors.forename: E
authors.initials: E
authors.lastname: Kringlen
mesh_terms: D000328:Adult; D001008:Anxiety Disorders / Q000145:classification / Q000175:diagnosis / Q000235:genetics; D003866:Depressive Disorder / Q000145:classification / Q000175:diagnosis / Q000235:genetics; D005260:Female; D006801:Humans; D008297:Male; D009664:Norway; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data*; D011618:Psychotic Disorders / Q000145:classification / Q000175:diagnosis / Q000235:genetics; D012307:Risk Factors; D012559:Schizophrenia / Q000145:classification / Q000175:diagnosis / Q000235:genetics*; D012565:Schizophrenic Psychology; D014429:Twins, Dizygotic / Q000235:genetics; D014430:Twins, Monozygotic / Q000235:genetics