underlying individual differences in the vulnerability for the development of an alcohol use disorder. In light of such efforts, the identification of more narrow behavioral phenotypes, or endophenotypes, for alcoholism has received increased attention (e.g., Hines et al., 2005), as is the case for most psychiatric disorders (Burmeister, 1999; Gottesman & Gould, 2003). A good endophenotype should be narrowly defined, readily identifiable, and related to the disorder of interest (Hutchison et al., 2002). When used correctly, endophenotypes for psychiatric disorders are expected to increase the power to detect specific genes underlying the risk for a given disorder.
