Alcohol dependence was the first behavioral disorder to have validated genetic findings. The alcohol metabolism gene, ALDH2, was initially found in the early 1980s to decrease the risk of alcohol dependence by increasing the levels of acetaldehyde in the blood, leading to uncomfortable physiologic effects including facial flushing, nausea, and tachycardia. A second alcohol-metabolizing gene, ADH1B, also decreases the risk for alcohol dependence by increasing ethanol oxidation to acetaldehyde. In addition to associations between alcoholism and alcohol-metabolizing genes, a GABA receptor gene, GABRA2, has been associated with alcohol dependence. The mechanism for this association is believed to be due to GABA mediation of behavioral affects of alcohol.
