Human dopamine transporter gene polymorphism (VNTR) and alcoholism

The dopamine transporter (DAT1) is responsible for taking released dopamine back up into presynaptic terminals and terminating dopaminergic activity. It has been shown that cocaine binds to the dopamine transporter and blocks dopamine reuptake in a fashion that correlates with cocaine reward and reinforcement. To determine the role of this gene in the development of alcoholism, we have used two approaches, relative risk and haplotype relative risk. The relative risk approach involved 162 alcoholic probands who were categorized into type I and type II, and 89 unrelated normal controls. In the haplotype relative risk approach, 29 trios (father, mother, and proband) were genotyped with dopamine transporter gene polymorphism. Comparison of allele frequencies between total alcoholics, subtypes of alcoholics, and normal controls were negative. The results of haplotype relative risk, differences between alleles transmitted and nontransmitted, were also negative. However, both approaches produced similar results. Therefore, we concluded that the VNTR polymorphism in DAT1 gene is not associated with alcoholism susceptibility genes in our samples.