The strengths of this study come from combining multiple-ancestry discovery, replication, and functional assessment of genetic variants in the relevant tissue for drug abuse, the human brain. This approach was only possible through broad sharing of data in the genetic research community. In our opinion, keys for further advances in the genetics of addiction include continuing to take on the valuable but complex tasks of leveraging shared data for much larger sample sizes, as exemplified with large-scale GWAS meta-analyses for psychiatric disorders (Cross-Disorder Group of the Psychiatric Genomics, 2013; Schizophrenia Working Group of the Psychiatric Genomics, 2014), and integrating the power of GWAS with functional studies to highlight potential biological processes underlying statistical associations of variants with phenotypes.
