The four studies with the Cys allele, two studies of heroin dependence and abuse, and three studies of multi-drug dependence were analyzed separately. However, they were also combined with AD and alcohol abuse considering that alcohol and drug dependence have been reported to share common genetic risk(84-86). The results showed that there was still strong evidence of association with ADH1B His and Cys in both allelic (Arg vs. His and Cys) and genotypic analyses (Table 1). The overall P value was 4×10−31 and OR was 1.98 (1.76, 2.22) for the allelic analysis, which was stronger under the dominant model. The Asian studies produced an allelic P value of 6×10−32 (OR = 2.17 (1.9, 2.46)), and significant results were found consistently under the dominant and recessive models (P = 9×10−32 and 2×10−31, respectively). Significant association was further detected in the combined Asian and European studies and non-Asian studies (P = 1×10−28 and 1×10−6, respectively). In contrast, the European studies showed moderate evidence of association with an allelic P value of 0.0007. The Mexican studies showed weak association (P = 0.034) possibly
