who are heterozygous experience a flushing response after consuming alcohol and have a substantially reduced risk of alcohol dependence compared with people who are homozygous for the functional ALDH2–1 allele. People who are homozygous for the defective ALDH2–2 allele experience an even more severe response to alcohol and have a risk of alcohol dependence that is close to zero. Thus, the ALDH2–2 allele is said to have a protective effect on the risk of alcohol dependence.
