Polymorphism of Genes Encoding Selenoproteins in the Indigenous Population of Siberia: Adaptive Variant rs1133238-A of the SEPHS2 Gene

In the present study, we analyzed the distribution of polymorphism variants of 25 genes encoding selenoproteins in indigenous Siberian populations on the basis of data on the variability of exons and adjacent noncoding DNA sequences. The study showed that there are virtually no polymorphism variants in the indigenous population of Siberia that differ greatly in frequency from those in the East Asian population, which could indicate the effect of selection on genes encoding selenoproteins. Nevertheless, we have proposed a set of loci in exons (rs3732532 of TXNRD3 gene, rs1050450 of GPX1 gene, rs6748996 of SELENOI gene, rs225014 of DIO2 gene) and noncoding region of genes (rs2291250 of SELENOS gene, rs201938903 of SELENOW gene, rs11258324 of SEPHS1 gene); further study of their polymorphism in different ethnic groups of Siberia is quite reasonable. The most promising locus is rs1133238 of the SEPHS2 gene. The frequency of the rs1133238-A variant was found to exceed 30% in Northeastern Siberia, although its frequency is significantly lower (~12%) in other regions of Siberia. Considering the association between the rs1133238-A variant and blood mercury levels in Canadian Eskimos, it is suggested that the increased frequency of the rs1133238-A variant in populations of the coastal regions of Northeastern Siberia (Koryaks, Chukchi, Eskimos) may be due to the protective role of this allele against the effects of mercury compounds on the body.