genetic studies including small sample sizes and limited ability to tag all regions of a gene. However, results from more recent genetic association studies remain inconsistent with both positive (Hack et al., 2010, Filbey et al., 2011; Landgren et al., 2011; Van der Zwaluw et al., 2011; Bhaskar et al., 2011) and negative (Kasiakogia-Worlley et al., 2011; Creemers et al., 2011, Heath et al., 2011, Wang et al., 2011, Luo et al., 2011, Schumann et al., 2011) evidence for association between DRD2 and alcohol problems. Interpreting this literature is further complicated by the 2004 discovery that the Taq1A polymorphism that had been most extensively studied was actually located 10 kb downstream from DRD2 in a neighboring gene, ankyrin repeat and kinase domain containing 1 (ANKK1) (Neville et al., 2004). The Taq1A variant is located within an exon of ANKK1, causing a non-synonymous coding change that may affect the substrate binding specificity of the gene product. It has been hypothesized that ANKK1 may be involved in the dopaminergic reward pathway through signal transduction (Neville et al., 2004). There have been many reviews of the DRD2 literature that provide detailed analysis of the variation across these genetic association studies (Goldman, 1998; Noble
