Genetic variations in the dopaminergic system and alcohol use: a system-level analysis.

Alcohol use is highly heritable and has been associated with many gene variants, including those related to dopamine (DA). However, single gene association studies have shown inconsistent and small effects. Using a system-level approach, the current study aimed to estimate the overall effect of genetic variations in the DA system on alcohol use among male drinkers. One hundred seventy-six male college students who reported to have ever drunk alcohol were enrolled. Alcohol use was measured using the Alcohol Use Disorders Identification Test. Ninety-eight representative polymorphisms in all major DA neurotransmitter genes were genotyped. Using analysis of variance, we identified six single-nucleotide polymorphisms (SNP)s that made statistically significant contributions to alcohol use. Next, main effects and interactions of these SNPs were assessed using multiple regression. The final model accounted for approximately 20% of the variance for alcohol use. Finally, permutation analyses ascertained the probability of obtaining these findings by chance to be low, p ranging from 0.024 to 0.048. These results confirmed that DA-related gene variants made strong contributions to reported alcohol use and suggest that multiple regression can be a promising way to explore the genetic basis for multi-gene-determined human behaviors.