In terms of GWAS assessments, in contrast to the GWAS of smoking behaviors to date, GWAS of alcohol dependence have been less consistent in identifying genetic variants associated with alcoholism (Treutlein et al., 2009; Bierut et al., 2010; Edenberg et al., 2010). One main reason for the differences in results is that these initial studies of alcohol dependence are of modest size by GWAS standards, with only a few thousand subjects compared to the tens of thousands of subjects in the GWAS of smoking behaviors. Each study identified novel regions that have suggestive evidence of association with alcohol dependence, including PECR (Treutlein et al., 2009), an enzyme involved in fatty acid metabolism, PKNOX2 (Bierut et al., 2010), which plays a role in cell proliferation, differentiation, and death, and SLC22A18 (Edenberg et al., 2010), a solute carrier. However, there is not consistent replication across studies. In addition, the alcohol metabolizing genes previously found to be associated with alcohol dependence are not well queried on the genetic platforms used by these studies, so remain to be validated by GWAS. For instance, rs1229984
