only with respect to ethnicity, but also with major covariates (age, sex, nicotine and cocaine dependence), as removing or limiting covariates did not markedly affect the results (Supplementary Tables 3 and 4). These results are consistent with the recent meta-analysis of Asian populations (47 studies, AG (Arg/His) and AA (His/His) versus GG (Arg/Arg), OR=0.24 (95% CI 0.19, 0.31), p value=2 × 10−31)5.
