This study aims to examine the relationship between the functional polymorphism at the promoter region of the dopamine D2 receptor (DRD2) gene (i.e. –141C Ins/ Del) and variable number of tandem repeat polymorphism at the 3′ untranslated region of the dopamine transporter (DAT) gene (SLC6A3) with alcoholism in a case–control study. The cases (n = 203) were alcohol dependents with withdrawal symptoms, and the controls (n = 213) were sex- and ethnicity-matched individuals who were screened to exclude those with alcohol problems among four aboriginal groups (Atayal, Ami, Bunun, and Paiwan) and Han Chinese in Taiwan. To control for potential confounding factors, we excluded tobacco abusers from control subjects in part of the analysis and compared the distribution of the genetic polymorphisms in alcoholics with severe medical complications versus those with less severe medical complications. There were no differences in allele and genotype frequencies of these two distinct genetic markers between alcoholics and control subjects in these five different ethnic groups. There was no significant linkage disequilibrium between the –141C polymorphism and two other DRD2 polymorphisms (TaqI A and NcoI). The results remained unchanged when cases were limited to alcoholics with more severe medical complications or when tobacco abusers were excluded from control subjects. The results suggest that both the DRD2 promoter region and the DAT gene do not play a significant role in conferring vulnerability to alcoholism.
aInstitute of Epidemiology, College of Public Health, National Taiwan University, Taipei, Taiwan; bDepartment of Psychiatry, Tzu-Chi General Hospital, and Institute of Human Genetics, Tzu-Chi Medical College, Hualien City, Taiwan; cInstitute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan dDepartment of Life Science, National Tsing Hua University, Hsinchu, Taiwan; eDepartment of Adult Psychiatry, Taipei City Psychiatric Center, Taipei, Taiwan
Correspondence to Professor Andrew T.A. Cheng, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan. E-mail: email@example.com
Received 15 January 2001
Accepted 7 August 2001