Risk of developing schizophrenia among Japanese high-risk offspring of affected parent: outcome of a twenty-four-year follow up.

AIMS: Prospective follow-up studies of high-risk children may help clarify the etiological factors in schizophrenia. While studies from North America, Europe and Israel have estimated the risk of schizophrenia at 7-16% in the offspring of an affected parent, no data have been reported for Asian populations. METHOD: We started a follow up of the offspring of Japanese schizophrenia patients in 1978. We investigated the estimated risk of schizophrenia in 51 high-risk offspring at the 24-year follow up. The effects of the parents' status, including history of psychiatric hospitalization and social functioning, on the risk in the offspring were also investigated. RESULTS: The cumulative incidence of schizophrenia was 13.7 % and the lifetime prevalence was estimated to be 13.5 +/- 4.8%. The association between the psychiatric hospitalization in the probands and the risk of schizophrenia in the offspring was not significant, and the Global Assessment of Functioning score was significantly lower in the probands with a history of psychiatric hospitalization than in those without such a history. CONCLUSIONS: The risk of developing schizophrenia in Japanese high-risk offspring might be comparable with the Western results. The present study suggests that the severity of the disease or the level of social functioning may not significantly affect the risk in Japanese offspring.

Human leukocyte antigen-A specificities and its relation with season of birth in Japanese patients with schizophrenia.

Several studies, including one from Japan, have observed an increase of Human Leukocyte Antigen (HLA)-A24 and A26 in schizophrenia, although others failed to observe the increase. No use of systematic diagnostic criteria and a not-adequately reliable typing technique might have affected the results in the previous studies. We investigated HLA-A specificities in Japanese patients with schizophrenia (DSM-IV), recruited from the same area as in the early Japanese study. A DNA-based technique (polymerase chain reaction-microtiter plate hybridization) was employed. No significant difference was observed in frequencies of any HLA-A specificities between patients and controls, including A24 and A26. No significant association was found between the HLA-A and birth-season in patients. Thus, no evidence was obtained for an association between HLA-A and schizophrenia from the Japanese population.