A number of gene identification projects are underway to identify the specific genes involved in alcohol dependence and related disorders (Begleiter et al., 1995; Prescott et al., 2005). The use of complementary strategies has contributed to the successful identification of a number of genes associated with alcohol dependence, many of which have now replicated in independent samples (Dick et al., 2006). The candidate gene strategy was used early on to demonstrate robust association with polymorphisms in genes encoding alcohol metabolizing enzymes: aldehyde dehydrogenase (ALDH; Harada, Agarwal, Goedde, Tagaki, & Ishikawa, 1982) and alcohol dehydrogenase (ADH; Whitfield, 1997).
