In summary, candidate gene studies have successfully detected functional variants in alcohol metabolism genes such as ADH1B, ADH1C, and ALDH2 associated with a risk of developing alcohol dependence in populations of Asian descent. Although alleles associated with reduced risk in Asians are rare in populations of African and European descent, they also reduce risk for alcohol dependence in these populations. Several GWAS of alcoholism have produced no conclusive evidence for specific genetic risk factors. The heterogeneous nature of the ascertainment strategies and the phenotypic measures used across studies could potentially explain the lack of a replicated association. Furthermore, the sample sizes in current alcohol studies are small compared with those in GWAS of other psychiatric disorders, limiting the power to detect genetic risk factors.
