Family study of schizophrenia: exploratory analysis for relevant factors.

Two hundred twenty-nine schizophrenic patients, diagnosed according to DSM-III criteria, and their first degree relatives (except children) were studied. HLA A1 and CRAG A1 antigens were used as markers of probable dopaminergic pathology and, therefore, as possible indicators of genetic homogeneity that might identify subgroups of families with a specific and recognizable liability. Data were subjected to a logistic analysis in which the dependent variable was the presence of schizophrenia spectrum disorders in relatives, and the independent variables were the presence or absence of HLA A1 and CRAG A1 antigens, the sex of the proband, the sex of the relative, the severity of illness in the proband, and the type of relationship. The results for the entire sample demonstrate that the type of relationship, the sex of the proband, and the sex of the relative have significant effects on the risk of disorder in the relatives. In addition, the presence in the proband of one of the CRAG A1 antigens is a valid classification criterion for identifying a relatively homogeneous subgroup of families of schizophrenic patients.