Alcoholism is a chronic relapsing disorder characterized by compulsive intake of excessive amounts of ethanol, loss of control over drinking, emergence of a negative emotional state (e.g. depressed mood, anxiety, stress sensitivity) upon withdrawal, preoccupation with obtaining ethanol and narrowing of the behavioral repertoire at the expense of social, occupational and recreational activities, tolerance to the intoxicating effects of ethanol and continued drinking despite negative consequences (DSM-IV criteria for alcohol dependence). Alcoholism develops over the course of years and involves spiraling cycles of intoxication/withdrawal/craving [1]. Genetic factors account for more than 50% of the risk to develop alcoholism, according to a polygenic and epistatic scheme in which each individual gene only exerts a small influence and interact with other genes to impart vulnerability to alcoholism [2]. In individuals developing ethanol dependence, interplay between these predisposition genes, environmental factors and ethanol exposure in turn produces changes in gene expression, which are believed to contribute, together with epigenetic alterations and post-translational modifications, to the long-term allostatic changes in the activity of brain emotional systems that underlie alcoholism [3]. Exploration of ethanol-responsive genes
