Lack of Association between a Functional Polymorphism in Dopamine and Opioid Receptor Genes with Alcoholism in South Indian Tamilian Population.

Abstract

Background: Single nucleotide polymorphism (SNP) of dopamine receptor (DRD2) and μ opioid receptor (OPRM1) genes are associated with susceptibility towards alcoholism. Hence, our study aimed to investigate the association of rs1799732 (DRD2) and rs1799971(OPRM1) with the risk of alcohol dependence in the south Indian Tamilian population and to compare the frequencies of these SNPs with major global populations. Methods: A total of 150 alcohol-dependent cases aged between 18 and 65 years who satisfied DSM-V were recruited from a de-addiction center (TTK hospital, Chennai). For the control group, 150 unrelated male blood donors with an AUDIT score of less than 8 were included. Genomic DNA was extracted and the alleles were genotyped using Taqman SNP genotyping assays by quantitative PCR. Results: Minor allele frequency (MAF) of rs1799732 and rs1799971 among controls were 16.7% and 50.3% respectively. Fisher’s exact test showed a highly significant difference in MAF of DRD2 and OPRM1 between south Indian controls and European as well as African populations. All the five genetic models of SNPs were evaluated using the Chi-square test revealed no statistically significant association between the SNPs and alcohol dependence. Conclusions: The present study did not find any association between DRD2 −141C Ins/Del and A118G OPRM1 polymorphism with alcoholism in the Tamilian population of south India.