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.

Xi-Cen Zhang,Bao-Jie Wang,Mei Ding,Yong-Ping Liu,Yi Liu,Jin-Feng Xuan,Jia-Xin Xing,Xi Xia,Atif Adnan,Jun Yao

doi:10.1002/brb3.1193

Abstract

BackgroundEpidemiological 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.MethodsWe 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.ResultsThe 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.ConclusionsIn 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.

Highlights

Schizophrenia is a multifactorial common psychiatric disorder (Casey, Rodriguez, Northcott, Vickar, & Shihabuddin, 2011), in which both environmental and genetic factors play an important role
The p‐value was calculated by 2 × 3 and 2 × 2 chi‐square test, in which the codomi‐ nant model, the recessive model, and the allele model were corrected by Bonferroni's correction and the p < 0.05/4 was statistically significant
We evaluated the association of the detected SNPs with schizophrenia risk using gender as a classification criterion conduct‐ ing by chi‐square test, as shown in Tables 3 and 4

Summary

| INTRODUCTION

Schizophrenia is a multifactorial common psychiatric disorder (Casey, Rodriguez, Northcott, Vickar, & Shihabuddin, 2011), in which both environmental and genetic factors play an important role. Dopamine receptors are proteins that bind to dopa‐ mine . Mutations in the genes may lead to the changes of their expression or their ability to bind to dopamine which initiates the process of schizophrenia. The dopamine receptor D2 (DRD2) gene is located in 11q22~23 extends over 270 kb and contains eight exons and seven introns. Most studies related to the association between the promoter region in DRD2 gene and schizophrenia mainly focused on rs1799732. To fully explore the association of DRD2 gene and schizophrenia, more and more studies are required for better understanding. We try to explore whether the polymor‐ phisms in the promoter region of DRD2 gene was involved in schizo‐ phrenia among the northern Chinese Han population

| MATERIALS AND METHODS

| DISCUSSION

| CONCLUDING REMARKS

Findings

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