that Aminobutyric acid (GABA), the major inhibitory neurotransmitter in the human central nervous system, is involved in many of the neurochemical pathways affecting alcohol use and related disorders (Buck, 1996; Grobin et al., 1998). Genetic markers were tested across the four GABA-A receptor genes in the region, and evidence emerged that alcohol-dependent individuals were more likely to carry a particular version of the GABRA2 receptor gene, suggesting it may be involved in the predisposition to alcohol dependence (Edenberg et al., 2004). This finding was subsequently replicated by multiple independent studies (Covault, Gelernter, Hesselbrock, Nellissery, & Kranzler, 2004; Fehr et al., 2006; Soyka et al., 2008; Xu et al., 2004).
