Alcoholism is a complex genetic disorder, affected by multiple genes, environmental and social influence, and interactions between genes and environmental factors (Bierut et al., 1999; Cloninger et al., 1981; Heath et al., 1997; Kendler et al., 1994). To identify genes contributing to the risk for alcoholism, the Collaborative Study on the Genetics of Alcoholism (COGA) has utilized both linkage and association approaches, using carefully ascertained and rigorously evaluated individuals in families with multiple alcoholics (Begleiter et al., 1995; Edenberg, 2002; Foroud et al., 2000). With this approach, COGA has provided evidence that a number of specific genes are associated with the risk for alcoholism, including GABRA2, CHRM2, hTAS2R16, GABRG3, OPRK1, PDYN, ADH4, NFKB1, TACR3, NPY2R and ACN9 (Dick et al., 2004; Dick et al., 2008; Edenberg et al., 2004; Edenberg et al., 2006; Edenberg et al., 2008; Foroud et al., 2008; Hinrichs et al., 2006; Wang et al., 2004; Wetherill et al., 2008; Xuei et al., 2006).
