Two criteria for the evolutionary selection of ALDH2*2 other than as a protection against alcohol disorder

Adaptive Genetic Variation and Population Differences
Author links open overlay panelChao-QiangLai

“It is unlikely that the high frequency of these risk alleles was under recent selection by alcoholism.

“Goldman and Enoch93 proposed two possible types of selection. First, mycotoxins (aflatoxins, in particular), which can cause hepatic disease and cancer, are commonly present in moldy rice, and ALDH enzymes can convert fungal protoxins found in moldy rice to toxins. Thus, heterozygotes of the mutation at ALDH produce less toxins and have an advantage over those who are homozygous for the major allele of ALDH.

“Second, many infectious bacteria and protozoa are very susceptible to acetaldehyde. Thus, carriers of ALDH2*2, who have high plasma concentrations of acetaldehyde, may better resist microbial infections and thus possess a selective survival advantage. While this hypothesis remains to be proven, this speculation suggests that adaptation based on one selective force may result in higher risk for other diseases.”

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