Among the 10 independent EA cohorts contributing to GENOA, OA was defined by Diagnostic and Statistical Manual criteria for opioid abuse or dependence (DSM-based; N = 17,061) or by frequency of use (FOU) of illicit opioids (e.g., injecting heroin 10 or more times in the past 30 days; FOU-based; N = 11,976; Supplementary Table 1). SNP-based heritability for both phenotypes was strong (DSM-based: h2 = 0.11, SE = 0.03; FOU-based: h2 = 0.18, SE = 0.04) and their genetic correlation robust (rg = 1.05, SE = 0.16; SNP-based genetic correlations are not bound by 1.0).
