A DSM-III family study of the nonschizophrenic psychotic disorders.

The authors conducted a blind DSM-III family study based on probands diagnosed from long-term follow-up information as having schizophreniform disorder, schizoaffective disorder, or psychotic affective illness. The pattern of psychopathology in relatives of schizophreniform probands closely resembled that found previously in relatives of schizophrenic probands. Relatives of schizoaffective probands had an excess risk for schizophrenia, other psychoses, and bipolar illness. The pattern of illness found in relatives of the probands meeting Research Diagnostic Criteria for mainly schizophrenic schizoaffective disorder appeared indistinguishable from that of relatives of schizophrenic probands. Relatives of probands with psychotic affective disorder had an excess risk for schizophrenia and for unipolar and bipolar affective disorder.