Association between D2 Dopamine Receptor Gene Polymorphisms and Reward Dependence Personality Traits

ABSTRACT

BACKGROUND: The dopaminergic genes have been implicated with some personality traits. Many recent studies indicated that there is a correlation between D2 dopamine receptor gene(DRD2) polymorphisms and the personality traits. The purpose of this study is to investigate a possible association between DRD2 gene (TaqI A, TaqI B) polymorphism and personality traits. METHODS: The subjects were consisted of 173 blood-unrelated young female Koreans with a mean age(+/-SD) of 13.88(+/-0.29) years. These volunteers were recruited from one of the junior high schools in Seoul and were tested by the Korean version of the Temperament and Character Inventory(TCI). Genotyping of the DRD2 polymorphisms by PCR methods were carried out. Two DRD2 gene polymorphisms were classified and individually assessed as follows TaqI A1+ vs A1-, TaqI B1+ vs B-. The associations between the TCI scores and TaqI A, TaqI B polymorphisms were assessed by Student's t-test. RESULTS: In the 173 subjects, the allele frequencies of the DRD2 TaqI A1, TaqI B1 alleles ranged from 0.42 to 0.43, and these results are quite different from the ranges of 0.15-0.20 in the case of a Caucasian population. The genotype frequencies of DRD2(TaqI A1, TaqI B1) variants showed no significant deviation from the Hardy-Weinberg equilibrium. RD4(dependence vs. independence) of Cloninger's TCI, a sub-dimension of Reward Dependence, was significantly higher in the subjects having DRD2 less frequent alleles than those without these alleles. CONCLUSION: This study suggests that the female subjects carrying the less frequent DRD2 alleles exhibited higher reward-dependent personality trait compared to those without these alleles.