The alcohol dehydrogenases (ADH) are a group of alcohol metabolizing enzymes that occur in many organisms. Aldehyde dehydrogenase (the most important in this context is ALDH2) is the next enzyme in this metabolic pathway. The first ADH was purified in 1937 from Saccharomyces cerevisiae(Negelein and Wulff 1937). In humans, the ADH isozymes are encoded by at least seven genes, and genetic association studies of genes in the ADH gene cluster with alcoholism and drug dependence have a longstanding history of decades with the most studied genes being ADH1B and ADH1C. Similarly, ALDH2 has long been studied with respect to alcohol dependence. Our recent meta-analyses confirmed strong associations of the ADH1B(Li et al. 2011) and ALDH2(Li et al. 2012) genes with alcoholism and alcohol-related medical diseases (P = 1×10−36 and OR = 2.06; P = 3×10−56 and OR = 0.23, respectively). Because the three genes are biologically related in terms of the functions of their encoded enzymes or pathways, genotype data of ADH1C was also analyzed. In this study, our findings strongly support that ADH1C 350Ile may lower the risk for
