Cousin marriages and schizophrenia in Saudi Arabia.

The rate and degree of consanguinity in the parents of 143 schizophrenics who satisfied the DSM-III diagnostic criteria, was compared in the same number of controls matched for age, sex and socioeconomic class. A family history of disorders suggestive of schizophrenia in the offspring of consanguineous parents who were schizophrenic, was compared with the incidence of a similar history in the schizophrenic offspring of non-consanguineous parents. There was no statistically significant difference in the former, but there was in the latter. This finding supports the theory of a familial tendency towards schizophrenia and the possibility of recessive or a multigene pattern of inheritance.