ALDH2 and hyperinsulinemic hypoglycemia, familial, 4: There are two major aldehyde dehydrogenase (ALDH) isoenzymes in the liver: cytoplasmic ALDH1 and mitochondrial ALDH2. The primary pathway by which ethanol is metabolized involves its degradation by alcohol dehydrogenase into acetaldehyde (an intermediate metabolite), which is then acted upon by ALDH and converted into acetic acid [49]. Previous studies have reported a widespread prevalence of ALDH deficiency in Oriental populations [50], and thus, it can be interpreted that Asians metabolize ethanol less efficiently than non-Asians.