ALDH2*504Lys appears to confer protection against some diseases such as alcohol liver disease. The unpleasant sensations experienced by heterozygotes for ALDH2*504Lys (even more so by the homozygotes) after drinking, such as the flushing reaction in many East Asians, hinder/stop further heavy drinking, thus reducing serious harm to the liver and other relevant organs (Yu et al., 2002). However, some social attitudes reduce this protection by promoting drinking in many ethnic groups of East Asia (Hasituya et al., 2007), resulting in more serious diseases in the ALDH2*504Lys heterozygotes.
