Alcohol use disorders are prevalent, affecting more than 8% of the U.S. population (Grant et al., 2004). They have multiple and complex etiologies including a strong genetic component, with heritability estimates ranging from 50–60% (Gelernter and Kranzler, 2009). Among the most widely studied genetic associations with alcohol dependence (AD) are those involving single nucleotide polymorphisms (SNPs) contained in a ~140 kb haplotype block spanning the 3’-region of GABRA2 and the adjacent intergenic GABRA2-GABRG1 region on chr4p12 (Covault et al., 2008, Edenberg et al., 2004, Covault et al., 2004). The association of SNPs in this region with AD has been replicated in multiple studies and across different populations (Ittiwut et al., 2012, Enoch et al., 2009, Lappalainen et al., 2005, Bauer et al., 2007, Fehr et al., 2006, Soyka et al., 2008, Li et al., 2014), but lack of replication has also been reported (Matthews et al., 2007, Lydall et al., 2011). SNPs in this haplotype block have also been associated with drug dependence (Agrawal et al., 2006), suggesting that variability in replication may relate in part to differing co-morbidities among
