Schizoaffective disorders. Results of a genetic investigation, I.

1004 first degree relatives fo 150 schizoaffective patients (41 males, 109 females) were studied and a total morbidity risk of 29.6% of schizoaffective spectrum disorders were found. The relatives show an increased morbidity risk for schizophrenia (5.26%) and affective disorder (6.55%) with a high incidence of catatonia and unipolar depression; schizoaffective secondary cases were only found in 3%. There is no significant difference in morbidity between parents, siblings and children. The morbidity risk of neuroses is 5.3%, for personality disorders 7.2% and for suicides without spectrum diagnosis 1.8%. Off-spring of affected parents show a morbidity risk twice as high as that of off-spring of non-affected parents. The findings do not support the present concept of the ICD (International Classification of Disorders) of WHO, which subsumes schizoaffective disorders under the major rubric of schizophrenia. From a genetic viewpoint schizoaffective disorder takes an intermediate position between schizophrenia and affective disorders. None of the present hypotheses of the mode of inheritance is supported by the findings.