4 ms·
These mutations do have a lot of spread outside of China. For example Fig. 1 of this paper (http://www.medgenetics.ru/UserFile/File/Borinskaya%202009%20AJHG%20D
by dynm 5y ago
These mutations do have a lot of spread outside of China. For example Fig. 1 of this paper (http://www.medgenetics.ru/UserFile/File/Borinskaya%202009%20AJHG%20Distr%20ADH1B%2047His.pdf http://www.medgenetics.ru/UserFile/File/Borinskaya%202009%20...) shows a high incidence of ADH1B in the Middle East.
Is it really required that these genes are equally selective everywhere? If the adaptation theory were true, that would depend on how widely available alcohol was, as well as how harmful it is to lose the extra calories from rotting fruit, etc. No particular reason to think it would be equal everywhere.
- nl 5y agoThanks for this. That paper led me down a rabbit hole and I ended up with this: Evidence of positive selection on a class I ADH locus It seems unlikely that the selection was recent and associated with alcoholism, the modern phenotypic manifestation of the polymorphism.... Mycotoxins, from toxin-producing fungi found in moldy rice, can be converted by the host ALDH enzymes from protoxin to toxin, and the effects of mycotoxins can be further potentiated by ethanol. If the incidence of hepatic disease found in many East Asians, especially JPN, is related to the consumption of mycotoxins, then individuals carrying the deficient ALDH22 variant with lowered alcohol consumption would be selectively favored.*[1] So it sounds like it isn't alcoholism that is being selected against, but instead resistance to mouldy rice born infections, which is correlated with this gene. That explains the geographic distribution quite well, too. [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1821113/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1821113/