Dopamine receptors are associated with reward and dependence towards alcohol. The polymorphisms of dopamine D2 receptor (DRD2) genes have been reported to be involved in susceptibility to alcoholism. Therefore, we investigated the association of three single-nucleotide polymorphisms (SNPs) in DRD2 and ankyrin repeat and kinase domain containing one (ANKK1) genes with alcohol dependence in Korean subjects, who were classified by the criteria of the Lesch typology.
The DRD2 −141C (Insertion (Ins)/Deletion (Del)), exon8 (A/G) and the ANKK1 TaqIA (A1/A2) polymorphisms were genotyped in a case–control sample consisting of 245 alcohol-dependent (AD) patients and 110 healthy controls. AD patients were classified into four subtypes by the Lesch typology. The majority of them (77.1%) were Lesch type 1. Differences in genotype and allele frequencies were examined between the AD patients and the controls. Also those analyses were done between the Lesch type 1 group and the controls.
There were significant differences in the genotype and allele frequencies of −141C Ins/Del and TaqIA A1/A2 between the AD patients and the controls. However, there were no significant differences in genotype or allele frequencies of exon8 A/G between the AD patients and the controls. The −141C Ins/Ins and TaqIA A1+ variants were associated with Lesch type 1 AD patients. When analysing haplotypes of three SNPs, the odds ratio of −141C Ins-A-A1 was 2.286, while the odds ratio of −141C Del-G-A2 was 0.323.
The present study showed a significant difference in DRD2 −141C and ANKK1 TaqIA polymorphisms between the AD patients and the controls. Our findings suggest that −141C Ins and TaqIA A1 alleles can be a predisposing factor for alcohol dependence in the Korean population.
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