Genetic and environmental factors contribute to individual susceptibility to alcohol dependence. Twin studies estimate that heritable influences explain 47-64% of variance in risk for alcohol dependence (Heath et al., 1997; Knopik et al., 2004). Several past research efforts have focused on targeted gene approaches to shed light on the genes that underlie these heritable influences. This has led to the proposal of hundreds of candidate genes that contribute to the development of alcohol dependence (Yu et al., 2008). A few GWA studies have also explored genes potentially involved in alcohol dependence (Bierut et al., 2010; Edenberg et al., 2010; Farrer et al., 2009; Heath et al., 2011; Hodgkinson et al., 2010; Joslyn et al., 2010; Treutlein et al., 2009; Zlojutro et al., 2011). Despite extensive candidate gene studies and several GWA studies, little consensus exists over which if any genes contribute to the genetic basis of alcohol dependence.
