Most people have two forms of the acetaldehyde dehydrogenase, a low KM mitochondrial form and a high KM cytosolic form. In susceptible persons, the mitochondrial enzyme is less active due to the substitution of a single amino acid (glutamate to lysine substitution at position 487; common in 50% Asian population), and acetaldehyde is processed only by the cytosolic enzyme. Because this enzyme has a high KM, less acetaldehyde is converted into