Genetic polymorphisms of CYP2D6, CYP1A1, GSTM1 and p53 genes in a unique Siberian population of Tundra Nentsi

The purpose of this study was to establish the frequencies of CYP2D6, CYP1A1, GSTM1 and p53 polymorphic genotypes in Tundra Nentsi, which comprises the small group of indigenous people belonging to Northern Mongoloids and Caucasians of Western Siberia. A total number of 102 Tundra Nentsi individuals and 96 Caucasians of Western Siberia were genotyped by means of polymerase chain reaction-based assays. Mutated alleles comprising CYP2D6*4, CYP1A1Val, GSTM1*0 and p53Pro were analysed along with the wild-type alleles. The results showed the intermedial position of CYP2D6*4 allele frequency in Tundra Nentsi, compared to Caucasians and Orientals (0.07 versus 0.2, P = 0.0003; 0.07 versus 0.003, P = 1 x 10(-6), respectively). Thus, our data indicate that the intermedial position of Tundra Nentsi between Orientals and Caucasians most likely shows the Caucasian ancestral origin of CYP2D6*4 allele. Comparative analysis of p53Pro allele frequency showed the pronounced ethnic differences with geographic gradient. Though the frequency of p53Pro allele ranged from 0.17 in Tundra Nentsi up to 0.3 in Caucasians of Western Siberia (P = 0.002), which is in agreement with the previously reported radial distribution of the known genetic markers. No differences were found in the CYP1A1Val allele distribution among Caucasians of Western Siberia and Caucasoid populations presented in other studies, whereas the frequency of Val allele in Nentsi was 1.5-fold higher (P = 0.076) compared to the Japanese group. It was found that the frequency of GSTM1 null genotype in Tundra Nentsi was only 39.8%. The frequency of GSTM1 null genotype in females was higher than in males (0.27 and 0.50, respectively) but that difference was not statistically significant. Comparative analyses of the distribution of putative markers towards cancer susceptibility, CYP1A1Val, GSTM1*0 and p53Pro alleles, have shown that the healthy Tundra Nentsi population (Northern Mongoloids) have a low number of p53Pro alleles and GSTM1*0/*0 genotypes and a high level of CYP1A1Val alleles. Further investigations of gene polymorphisms in isolated Northern native populations would be valuable in clarifying the origin of Northern natives. All this is important for comparative analyses of pharmacogenetic data in Mongoloid populations.