Sex concordance in proband-relative pairs with schizophrenia

Sex concordance rates were investigated in 278 schizophrenic probands, who had at least one first-degree relative with schizophrenia, in order to find out whether the illness affects the same sex more often than the opposite sex when two close relatives become ill. No such unusual concordance rates were found in proband-relative pairs with schizophrenia. When 118 of the 278 probands were examined who had at least one parent with schizophrenia, the morbidity risk for schizophrenia in siblings of the same sex as the schizophrenic probands was significantly higher than that found in siblings of the sex opposite that of schizophrenic probands.