Morbid risks of schizophrenia and mood disorders among first-degree relatives of patients with schizophrenia and mood disorders

We investigated the morbid risks of schizophrenia and mood disorders in the relatives of probands with such disorders. In total, 377 schizophrenic patients and 322 mood disorder patients (comprising 246 patients with unipolar disorder and 76 patients with bipolar disorder) were recruited, and the morbid risks of these psychiatric disorders were evaluated in their first-degree relatives. Of the families of schizophrenic probands, 30 (8.0%) had additional members with schizophrenia, while 11 (2.9%) had members with mood disorder. Of the families of unipolar probands, 10 (4.1%) had members with schizophrenia, while 17 (6.9%) had members with unipolar disorder and 2 (0.8%) with bipolar disorder. Of the families of bipolar disorder probands, 2 (2.6%) had members with schizophrenia, while 7 (9.2%) had members with unipolar disorder and 5 (6.6%) with bipolar disorder. Our data indicated that the morbid risk of schizophrenia in the relatives of schizophrenic probands, and the risk of mood disorder in the relatives of mood disorder probands, were higher than the prevalence in the general population. Moreover, there was an increased morbid risk of schizophrenia in the relatives of patients with mood disorder. Our results suggest that genetic factors play a role in the etiology of mood disorder and schizophrenia, and that genetic factors associated with schizophrenia may be related to those associated with mood disorder.