There is heterogeneity among Asian populations in the allele frequency and in the strength of the protection. Han Chinese and Japanese men show the strongest protection (the OR for heterozygotes = 0.18–0.26) (Whitfield, 2002, Chen et al., 1999b, Luczak et al., 2006, Park et al., 2013). Logistic regression of combined ADH2 and ALDH2 genotypes in Han Chinese found that in the presence of active ALDH2 (ALDH2*1 homozygosity), a single ADH1B*2 allele gave an odds ratio (OR) of 0.22, and two ADH1B*2 alleles gave OR = 0.14, both with p<10−6 (Chen et al., 1999b). Minority populations in Asia show less protection (Shen et al., 1997, Thomasson et al., 1994). Meta-analyses that lump all Asian groups show less protection (OR ~ 0.4; p = 10−33 to 7×10−42) (Zintzaras et al., 2006, Li et al., 2011, Luczak et al., 2006, Whitfield, 1997). Because drinking was not as common among Asian women, their overall risk was less and therefore the protective effect were also less (Luczak et al., 2006, Zintzaras et al., 2006).
