Alcohol dependence, which constitutes major public health problems, is a chronic relapsing disorder characterized by compulsive seeking, abuse, tolerance, and physical dependence on alcohol. It is a multifactorial disorder caused by complex interaction of genetic and environmental factors (Gelernter and Kranzler 2009; Kendler et al. 2007). The alcohol dehydrogenases and aldehyde dehydrogenases metabolize alcohol into acetaldehyde and then into acetate. There are two major aldehyde dehydrogenase (ALDH) liver isoforms, cytosolic and mitochondrial, encoded by the aldehyde dehydrogenase 1 gene (ALDH1) and aldehyde dehydrogenase 2 gene (ALDH2), respectively. The ALDH2 gene was hypothesized to alter genetic susceptibility to alcohol dependence (AD) and alcohol-induced liver diseases.
