Alcohol dependence is characterized by the emergence of a set of specific cognitive, physiological, and behavioral phenomena in which the use of alcohol eventually takes on greater importance than other salient activities and often results in physical and psychological harm (Ehlers and Chester, 2009). There is consistent evidence from family, twin, and adoption studies for the existence of a genetic contribution to the etiology of alcohol dependence (see Cotton, 1979; McGue, 1994, 1999; Heath et al., 1997). The individual differences seen in risk for alcohol dependence are almost certainly due to the combined effects of many genes, each exerting a specific effect on protection from and risk for the disorder, as well as gene-gene and gene-environment interactions (see Dick et al., 2006a; Kohnke, 2008). Over the last decade there have been several large studies in which investigators have identified families with alcoholism, collected DNA and family relationships, and conducted linkage and association analyses with the goal of identifying the genes associated with alcohol dependence (see Long et al., 1998; Reich et al., 1998; Ehlers et al., 2004; Hill et al.,
