Association between Smoking Habits and Dopamine Receptor D2 TaqI A A2 Allele in Japanese Males: a Confirmatory Study

Our previous study showed that A2 allele of dopamine D2 (DRD2) TaqI A polymorphism related to smoking habits, which was opposed to the results of studies for Caucasians. In order to confirm our finding, a similar study was conducted for the first-visit outpatients of Aichi Cancer Center Hospital, who participated in HERPACC-II (Hospital-based Epidemiologic Research Program at Aichi Cancer Center - II). Among consecutive 1,577 first-visit patients between November 2000 and February 2001, 800 patients provided a 7ml of peripheral blood. Smoking habit data were available for 798 participants. Excluding five participants aged < 20 years or ≥ 80 years, the remaining 793 participants (346 males and 447 females) were analyzed. The DRD2 genotype was determined by a new method, polymerase chain reaction with confronting two-pair primers (PCR-CTPP). In males, current smokers were 35.3% of individuals with A1A1 genotype, 43.1% of individuals with A1A2 genotype, and 57.0% of individuals with A2A2 genotype, while in females, they were 19.6%, 14.6%, and 10.9%, respectively. Age-adjusted odds ratio (OR) of current smoking relative to A1A1 was 1.61 (95% confidence interval, 0.71-3.46) for A1A2 and 2.32 (1.02-5.29) for A2A2 in males, and 0.72 (0.32-1.61) and 0.51 (0.22-1.18) in females, respectively. The present study indicated that Japanese males with A2A2 genotype have a higher risk of being current smokers. No association for Japanese females suggested that female smoking behavior is differently affected in biological and/or psychological manner.