Is the roller coaster ride in schizophrenia genetics coming to an end? breakthrough or wishful thinking?

Case-control study of association between the functional candidate gene ERBB3 and schizophrenia in Caucasian population

Schizophrenia is a common psychiatric disorder with a complex genetic aetiology. Evidence shows that the oligodendrocyte and myelin-related genes including ERBB3 are closely related to schizophrenia. Two recent studies (Kanazawa et al. (Am J Med Genet B Neuropsychiatr Genet 2007;144:113)) and Watanabe et al. (Neurosci Res 2007;57:574) reported there was no association between ERBB3 and schizophrenia in Japanese population. We investigated the ERBB3 gene given the putative functional nature of the gene and population heterogeneity between Asian and Caucasian. Scottish case and control samples were sequenced with four SNPs (rs705708 at intron 15, rs2271189, rs773123, rs2271188 at exon 27). We detected rs773123, which is a nonsynonymous Ser/Cys polymorphism located seven bases downstream of rs2271189, with P=0.034. The subgroups of male patients and patients with age at onset <45 showed evidence of significant association with P values of 0.0046 and 0.0055, respectively. To our knowledge, this is the first association study between ERBB3 and schizophrenia in the Caucasian population. Further investigation with large sample size should be helpful to clarify the nature of the gene.

Association between the ionotropic glutamate receptor kainate3 (GRIK3) Ser310Ala polymorphism and schizophrenia in the Indian population

Various studies have been done to check the status of glutamate receptor gene in the pathogenesis of schizophrenia. The T928G (Ser310Ala) polymorphism of ionotropic glutamate receptor kainate 3 gene (GRIK3) and its positive association with schizophrenia was reported in Caucasians, whereas no association of this polymorphism with schizophrenia was shown in two other populations, Chinese and Japanese. However, no literature is available regarding the prevalence of this polymorphism and its association with schizophrenia in the Indian population. As genetic susceptibility profiles in India are often different from those of white Caucasians or Orientals, we investigated the status of Ser310Ala polymorphism of GRIK3 in 100 schizophrenic patients and 100 healthy controls in the Indian population by the PCR-RFLP (restriction fragment length polymorphism) method. A statistically significant difference in the genotype and allelic distributions (P<0.000001 and P=0.01, respectively) of Ser310Ala polymorphism was found in schizophrenics than in control, considering Ala-allele as being associated with the disease (OR=1.7, 95% CI=1.137-2.540). Our study suggests a potential role for GRIK3 for susceptibility to schizophrenia in Indian population.