Arctic populations live in an environment characterized by extreme cold and the absence of plant foods for much of the year and are likely to have undergone genetic adaptations to these environmental conditions in the time they have been living there. Genome-wide selection scans based on genotype data from native Siberians have previously highlighted a 3 Mb chromosome 11 region containing 79 protein-coding genes as the strongest candidates for positive selection in Northeast Siberians. However, it was not possible to determine which of the genes might be driving the selection signal. Here, using whole-genome high-coverage sequence data, we identified the most likely causative variant as a nonsynonymous G>A transition (rs80356779; c.1436C>T [p.Pro479Leu] on the reverse strand) in CPT1A, a key regulator of mitochondrial long-chain fatty-acid oxidation. Remarkably, the derived allele is associated with hypoketotic hypoglycemia and high infant mortality yet occurs at high frequency in Canadian and Greenland Inuits and was also found at 68% frequency in our Northeast Siberian sample. We provide evidence of one of the strongest selective sweeps reported in humans; this sweep has driven this variant to high frequency in circum-Arctic populations within the last 6-23 ka despite associated deleterious consequences, possibly as a result of the selective advantage it originally provided to either a high-fat diet or a cold environment.
KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This research was supported by European Research Council Starting Investigator grant FP7-261213 to T.K. C.T.-S., Y.X., Q.A., and M.S. were supported by Wellcome Trust grant 098051, and T.A. was supported by Wellcome Trust grant WT100066MA. M. Metspalu and R.V. received supported from the European Union European Regional Development Fund Centre of Excellence in Genomics to the Estonian Biocentre. T.K, M. Metspalu, and R.V. were supported by Estonian Institutional Research grant IUT24-1, and M. Metspalu received Estonian Science Foundation grant 8973.