No association between polymorphisms in the promoter region of dopamine receptor D2 gene and schizophrenia in the northern Chinese Han population: A case-control study.

Background: Epidemiological studies found that genetic factors are among the causes of schizophrenia, exclusively the genes involved in the dopamine system. Prior to this, the role of dopamine receptor D2 (DRD2) gene promoter polymorphisms and schizophrenia has been studied extensively, but there are still some uncertainties about these associations. The present study is focusing on the association between the DRD2 gene promoter region polymorphisms and schizophrenia in the northern Chinese Han population.

Methods: We sequenced 2,111-bp fragment of DRD2 gene promoter region in 306 schizophrenic patients and 324 healthy controls to find association between DRD2 and schizophrenia. SPSS version 18 0.0 was used to calculate odds ratios (OR), 95% confidence intervals (CIs).The Hardy-Weinberg equilibrium test and the confirmation of haplotypes were calculated using Haploview version 4.1. The association of schizophrenic risk of DRD2 genotypes, alleles, and haplotypes between case and control groups was calculated using the chi-squared test. PS program was used to calculate the Power analysis.

Results: The genotype frequencies of rs7116768 (p = 0.025) and rs1799732 (p = 0.042) were associated meagerly. After Bonferroni correction, there was no association found between DRD2 gene promoter region with schizophrenia risk in the northern Chinese Han population.

Conclusions: In this study, we did not find any significant difference between schizophrenia and the polymorphisms of DRD2 gene promoter region. A more forceful conclusion remains to be verified by further confirmatory experiments.