Subdividing the functional psychoses: a family hereditary approach.

Family genetic data, based on standardized and independent diagnostic procedures of index and secondary cases, confirmed the dichotomy between schizophrenias and affective disorders. The classical schizophrenic subtypes exhibited a significant tendency towards homotypia among their secondary cases. The genetic evidence did not support the monopolar-bipolar subdivision of affective disorder. Schizo-affective disorders impinged on the clear-cut schizophrenic and affective psychotic disorders and there was no homotypical tendency among the relatives of index cases with this diagnosis.