Japanese study had identified a mutant form of the enzyme aldehyde dehydrogenase (ALDH)that is responsible for some people feeling less or no hangover from consuming alcohol.
Researchers from Mitsukoshi Health and Welfare Foundation have found that the toxicity of acetaldehyde leads to hangovers in individuals who have a particular genetic makeup.
Aldehyde dehydrogenase (ALDH) is the most important enzyme involved in the removal of acetaldehyde, which is the foremost product of alcohol metabolism. If the enzyme is normal and active, then the acetaldehyde is metabolized quickly. If the enzyme does not function properly, then people may experience drowsiness, nausea, asthma and flushed face, along with cardiovascular problems.
People from East Asia often have a mutant allele called ALDH2*2 and an inactive ALDH that prevents them from drinking heavily because of feelings of uneasiness or unpleasantness. These people are not able to remove the acetaldehyde from their bodies and may suffer severe hangovers.
Results of the study had shown that in spite of negative consequences, people with a deficit ALDH might still develop tolerance to alcohol, after a period of heavy drinking. And these are the people likely to have the most severe of the hangovers.
Reference: Alcoholism: Clinical & Experimental Research, July 2005