GWASs represent the most recent paradigm shift for the gene discovery[43]. These hypothesis free genome scans allow interrogation of million of SNPs across thousands of genes at relatively modest cost[43]. Many GWAS’s of AUD, AD and alcohol consumption have been completed majorly in the European ancestry[28–30, 44–53]. First reported GWAS study for AD (Treutlein et al. 2009) identified 2 genome-wide significant SNPs (rs7590720 and rs134694) in combined male only sample of 1,460 AD subjects and 2,332 controls[44]. The closest gene to the association signal PECR (peroxisomal trans-2-enoyl-CoA reductase) is involved in the metabolism of fatty acids. Two subsequent AD GWASs did not identify any novel genome-wide significant loci (COGA, SAGE)[29, 54]. Further Heath and colleagues performed GWAS of quantitative indices of excessive alcohol consumption in moderate size cohort of Australian families but failed to identify any genome-wide significant variant[28]. Subsequent family and case control genome-wide efforts met with similar fate of limited success and non replication across different studies[52, 55]. At this point in time researchers already realized that AUD is highly polygenic and sample size of individual cohort is
