On the basis of PubMed query under the keywords 'addiction AND association* AND genome' followed by manually curation, we identified 7 GWAS on drug addiction, containing 11 independent samples. Five of them met our inclusion criteria: i) genetic association studies with case-control design, ii) published in peer-reviewed English scientific journals, iii) the original case-control genotype data is available (raw data available with adequate ethnic approval) and iv) the genotype data are generated by comparable genotyping platforms and arrays with density designs. Detailed raw data of the five GWAS datasets came from the Molecular Neurobiology Branch, NIH-IRP (NIDA) led by Dr. George Uhl, including i) 500 K SNP genotype data from 560 African-American poly-substance abusers who reported dependence on at least one illegal substance and 360 controls [25]; ii) 500 K SNP genotype data from 420 European-American poly-substance abusers who reported dependence on at least one illegal substance and 320 controls [25]; iii) 500 K SNP genotype data from 140 methamphetamine abusers of ethnic Han Chinese origin, with 240 Han Chinese controls [26]; iv) 500 K SNP genotype data from 100
