1982, Thomasson et al., 1991, Hurley et al., 2002, Edenberg, 2007, Crabb et al., 1989, Chen et al., 2009, Luczak et al., 2006, Goedde et al., 1992, Edenberg, 2012, Chen et al., 1999b, Whitfield, 2002, Hurley and Edenberg, 2012). In Han Chinese, the presence of a single ALDH2*2 allele in a background of homozygous ADH1B*1 gave an OR of 0.40; when combined with a single ADH1B*2 allele the OR dropped to 0.06 (Chen et al., 1999b). Meta-analysis of 22 datasets showed an OR of 0.22 for ALDH2*2 heterozygotes (Luczak et al., 2006). A later meta-analysis showed similarly strong protection against AD: OR = 0.22 (p = 1 × 10−44) under a dominant model that is probably close to the physiological effects of the variant (Li et al., 2012b). The protective alleles at ADH1B and ALDH2 act synergistically to give a relative risk of alcoholism in Asians of 1–10% (Chen et al., 1999a, Luczak et al., 2006).
