Meta analyses were performed using the inverse variance weighting approach of the METAL program.33 The phenotypic variance in ODE status explained by rs10799590 was calculated34 for the meta-analytic results using odds ratios, risk allele frequencies (RAFs), and prevalence estimates ranging from 0.005 (population prevalence of heroin dependence)12,35,36 to 0.25 (approximate prevalence reported for heroin dependence among users).12
