Kendler et al. (2011) performed a GWAS which used a quantitative measure of symptoms of alcohol dependence in a general population from the United States consisting of 2357 European Americans and 812 African Americans subjects from the Molecular Genetics of Schizophrenia (MGS2) control sample (Kendler et al., 2011). As compared to the dichotomous clinical diagnosis of alcohol dependence a symptom count of alcohol dependence phenotype is presumed to provide greater power for genetic analysis while remaining highly correlated with a clinical diagnosis (Grant et al., 2009; Whitfield et al., 2004). Subjects who reported drinking greater than 4 drinks in one day were retained and administered a 7-item questionnaire which assessed craving for alcohol, DSM-IV criterion for alcohol abuse (dangerous use) and criteria 1 (tolerance), 3 (loss of control), 5 (“great deal of time … ”), 6 (activities given up), and 7 (use despite knowledge of harm) for alcohol dependence. Subjects who reported consuming less than three drinks (excluding liftetime abstainers) in a day were considered social drinkers and served as the control comparison group. Factor analysis of the alcohol dependence
