(ADH1B) is involved in the conversion of ethanol to acetaldehyde; acetaldehyde is toxic and its accumulation leads to an unpleasant physiologic reaction involving headache, nausea, and heart palpitations. Polymorphisms in alcohol metabolism genes that affect acetaldehyde levels can have a profound effect on drinking behavior.49,50 For example, the ADH1B*2 allele rapidly oxidizes ethanol, and is protective against alcoholism; this effect is most evident among East Asian and Ashkenazi Jewish populations, in whom the frequency of this allele is high. Individuals carrying at least 1 of these alleles are far less likely to develop alcoholism. The advantage of the candidate gene approach is that it provides targeted hypothesis testing, but this approach is limited by knowledge of human biology.
