Therefore, the use of endophenotypes, or specialized intermediate phenotypes, has been proposed as a strategy to aid gene identification efforts for complex phenotypes, such as AD (Gottesman and Gould, 2003). Endophenotypes are rigorously defined (Ray et al., 2010) and allow for a critical analysis of genetic risk for alcohol use disorders (AUDs). As part of the COGA project, the use of endophenotypes has successfully led to the identification of genes associated with AD (Dick et al., 2006). Of note, Edenberg et al (Edenberg et al., 2004) reported that variation at the GABRA2 locus is associated with EEG β power. Another potential endophenotype is subjective response to alcohol, a measure of individual differences in sensitivity to the pharmacological effects of alcohol, and a predictor of the development of AUDs (Morean and Corbin, 2010; Quinn and Fromme, 2011). The exact pattern of subjective responses to alcohol associated with increased risk for alcohol problems, however, remains unclear. In the Low Level of Response (LLR) Model, high-risk individuals experience a dampened response to the full range of alcohol effects; thus a LLR to alcohol
