Under each ancestry-specific genetic variant lies a great biological story
A genetic variant that is extremely common in one population but completely absent in another population almost always leads us to a great biological discovery. Genetic variants that are positively selected in African populations are excellent examples (for e.g. sickle cell variants). A recent preprint reports an analysis of ~5000 whole genome sequences from Chinese population; the authors have mapped the genomic regions that are under positive selection in Chinese. While some of them are already known (MHC, ADH and ALDH2), one of them is novel, a region around gene SNX29 in chromosome 16, where the index variant is an intronic variant, rs75431978. The minor allele frequency of this variant is 0.17 in Asians and 0 in Europeans. The functional consequence of the variant is not clear (being an intronic variant, either it should be an eQTL or could be simply a marker of some structural variant in SNX29). But soon we will know, and I am quite sure the story will turn out fascinating.
Imagine: while none among the 740 million people living in Europe carry this variant, around 200 million individuals in China (17% of the population) carry this variant. What kind of environmental pressure would have driven this variant to such high frequency ? Only time will tell.
