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Consanguinity may contribute to the incidence of schizophrenia in offspring despite the usually accepted polygenic model of schizophrenia inheritance. Bedouin Arab families in southern Israel have a high rate of cousin marriages as do families throughout most Arab societies. We studied consanguinity in the parents of schizophrenic patients admitted in a defined catchment area of southern Israel, compared to a control group of parents of all infants born to Bedouin mothers in this catchment area. There was a small but significant increase in the rate of cousin marriages among the parents of schizophrenia patients compared to parents of infant controls. These results are consistent with claims that inbreeding can contribute to the incidence of schizophrenia even as a polygenic illness. However, the absence of a better matched control group limits confidence in the results. [ABSTRACT FROM AUTHOR]

Abstract: Haplotypes and haplogroups are linked sets of common DNA variants, acting as susceptibility or protective factors to complex disorders. Growing evidence suggests that dysfunction of mitochondrial bioenergetics contributes to the schizophrenia phenotype. We studied mitochondrial DNA haplogroups in schizophrenia patients. Since mitochondria are inherited from the mothers, we used healthy fathers as an ideal case-control group. Analysis of the distribution of mitochondrial haplogroups in schizophrenia patients compared to their healthy fathers (202 pairs) resulted in an over-representation of the mtDNA lineage cluster, HV, in the patients (p =0.01), with increased relative risk (odds ratio) of 1.8. Since mitochondrial DNA is small relative to nuclear DNA, a total mitochondrial genome analysis was possible in a hypothesis-free manner. However, mitochondrial DNA haplogroups are highly variable in human population and it will be necessary to replicate our results in other human ethnic groups. [Copyright &y& Elsevier]