The first large scale GWAS of OUD was published in 2013 [39*]. The authors analyzed a total of 5432 African-Americans and 6877 European-Americans across multiple sub-groups, allowing the overall cohort to serve as a discovery sample and two replication samples for the most significant findings. Meta-analyses were also performed in the entire cohort. Analyses were performed using either Diagnostic and Statistical Manual of Mental Disorders 4th edition (DSM-IV) symptom counts for opioid dependence or case-control status. For the symptom count variable, rs62103177 in KCNG2 was genome-wide significant in the final meta-analysis (p = 3.6 × 10−10). Additional variants in KCNC1 (rs60349741) and APBB2 (rs114070671) reached genome-wide significance in the combined analysis of the discovery and first replication sample, but were only nominally significant in the meta-analysis of the full cohort.
