The largest AD GWAS to date was performed by Gelernter et al. (2014a). The discovery sample consisted of 2,379 EA and 3,318 AA subjects (“Yale-Penn”) and 2,752 EA and 1,311 AA subjects from the SAGE sample (Bierut et al., 2010). The replication sample consisted of 1,746 EA and 803 AA subjects (Yale-Penn replication) and 1,806 EA AD cases and 1,978 EA controls from a previously analyzed German sample (Frank et al., 2012), which were used to replicate the results for the case-control phenotype. The Yale-Penn samples were not previously included in any other GWAS. In addition to being the largest AD GWAS to date, this was the first to impute the SNPs tested to include over 9 million in AAs and over 6 million in EAs. Similar to their previous analyses for cocaine and opioid dependence (Gelernter et al., 2014b; Gelernter et al., 2014c) and the analysis by Wang et al. (2013), the authors tested for association with a quantitative DSM-IV AD criterion count phenotype. They controlled for cocaine, opioid, and nicotine dependence criteria in the sample and meta-analyzed the
