To find alleles potentially associated with SD traits, we searched Medline in November 2013 using combinations of the following keywords: ‘drugs’, ‘alcohol’, ‘nicotine’, ‘opioid’, ‘addiction’, ‘dependence’, ‘genome-wide association studies’ and ‘GWAS’. We identified 16 articles, in which at least a gene showed near-significant association with a trait related to at least one of the considered drug dependencies (p < 5*10−7). A total of 24 genes (hereafter indicated as GWAS-relevant genes) were identified, as shown in Supplementary Table 1. We observed that the GWAS results are more consistent within the ancestral groups than between them, as anticipated. This trend is clearer for SD traits that were investigated by independent GWAS.
