Distribution of the arctic variant of the CPT1A gene in indigenous populations of Siberia

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Population screening of the Arctic variant, which has arisen due to the G > A mutation at locus rs80356779 in the CPT1A gene, has been performed for the first time among indigenous peoples of Siberia (Chukchi, Koryaks, Evens, Evenks, Yakuts, Buryats and Altaians) and East Asia (Koreans). It is assumed that CPT1A Arctic variant originated from Eskimo ancestors, probably as a result of adaptation to a high-fat diet and/or to the extremely cold environment. It is also known that the homozygous Arctic variant is associated with hypoketotic hypoglycemia attributable to CPT1A deficiency and high infant mortality and occurs at high frequency in American Eskimo. On the other hand, the association of CPT1A Arctic variant with increased levels of HDL-cholesterol and apolipoprotein A1 in blood plasma suggests that this mutation might have a cardioprotective role. In the present study, a high frequency of CPT1A Arctic variant has been found in coastal populations of Northeast Asia – in Koryaks (66 %), Chukchi (56 %) and Evens (30 %), and singularly (at a frequency of 1 %) in Evenks of Central Siberia. Five polymorphic loci relevant to the haplotypic structure of CPT1A gene (rs2278908, rs2278907, rs2924699, rs7112615 and rs2229738) were revealed by high-throughput DNA sequencing in addition to locus rs80356779 studied here. It was found that the Arctic variant haplotype has arisen only once on the basis of the haplotype, which is widespread in modern populations of Eurasia. We assume that the expansion of Eskimo culture of the sea mammal hunting as well as Eskimo assimilation by Chukchi and Koryaks have contributed to the spread of the CPT1A Arctic variant across the populations of indigenous peoples of Northeast Asia.