Studies of ADH1C variants have demonstrated decreased risk for alcohol dependence in those homozygous for ADH1C*1 compared to those with at least one ADH1C*2 allele in Asian populations (Higuchi et al., 1996; Shen et al., 1997). Modest associations between ADH1C*2 and increased alcohol dependence risk have also been demonstrated in European populations (Whitfield, 1997). Studies of linkage disequilibrium have indicated that the association between ADH1C*2 and alcohol dependence may be due instead to variants of ADH1B in some ethnic groups (Osier et al. 1999), although other studies have demonstrated independent effects of ADH1C*2 (Luo et al., 2006). It may be that ADH1C*2 has a larger effect on alcohol dependence in populations where ADH1B*2 is infrequent, such as Europeans and African Americans (Whitfield, 1997).
