The enzyme encoded by this gene belongs to the aldehyde dehydrogenase family of enzymes that catalyze the chemical transformation from acetaldehyde to acetic acid. Aldehyde dehydrogenase is the second enzyme of the major oxidative pathway of alcohol metabolism.
Two major liver isoforms of this enzyme, cytosolic and mitochondrial, can be distinguished by their electrophoretic mobilities, kinetic properties, and subcellular localizations. The ALDH2 gene encodes a mitochondrial isoform, which has a low Km for acetaldehydes, and is localized in mitochondrial matrix; in contrast the ALDH1 gene codes for the cytosolic isoform.
Most Europeans have two major isozymes, while approximately 50% of Northeast Asians have one normal copy of the ALDH2 gene and one mutant copy that encodes an inactive mitochondrial isoenzyme. A remarkably higher frequency of acute alcohol intoxication among Northeast Asians than among Europeans has been repeatedly shown to be related to the very much reduced activity of the mutant ALDH2-2 isoenzyme. During the 80's there has been a steady increase in the number of Japanese alcoholics who manage to overcome their genetically determined aversion to alcoholism from the dominant effects of an ALDH2-2 mutation. This trend demonstrates that, even among those least likely to succumb to alcoholism, there are social pressures to drink.
An activator of ALDH2 enzymatic activity, Alda-1 (N-(1,3-benzodioxol-5-ylmethyl)-2,6-dichlorobenzamide), has been shown to reduce ischemia-induced cardiac damage caused by myocardial infarction.
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