Vershubskaya Galina

Introduction. A dinucleotide deletion of AG at the rs781470490 locus of the SI gene (SI delAG variant) causes dysfunction of the sucrase-isomaltase enzyme and the inability to digest sugar. The deletion frequency in the world is 0.0021%, while among the Inuit (Eskimo) it reaches 17–20%. Research hypothesis: the SI delAG variant is common in all the populations of indigenous northerners.
The study aimed to ascertain the prevalence of the SI delAG variant in the Cis-Ural, Siberian, and Far East populations of the Russian Federation and compare it to that of the Inuit people.
Materials and methods. DNA genotyping and the SI delAG variant frequency analysis were carried out in the samples from study groups of Russians, Komi, Mansi, Khanty, Nenets, Shors, Evenks, Evens, Koryaks, Chukchi (n =613). Corresponding data for the Canadian and Greenlandic Inuit (n =391) were used for comparison.
Results and discussion. The deletion in samples from the Chukchi, Koryak, and Even study groups occurred in 14, 7, and 4%, respectively; there was no the deletion found in the samples of the other Siberian and Cis-Ural groups. The carriage of the SI delAG variant decreases with the distance from the area of the Greenlandic Inuit. The Inuit, Chukchi, and Koryak groups form a distinct cluster. The Paleo-Eskimo do not carry the deletion. Minimal amounts of sugar-containing products appeared in the diet of the Greenlandic and Canadian Inuit at the end of the 19th century, 200 years later than in the diet of aboriginal northerners of Eurasia.
Conclusions. There was no SI delAG variant found in the samples of the indigenous people of West Eurasia high latitude regions. The deletion emerged in Neo-Eskimo population 1.2–2 thousand years ago and has been retained in the small numbered isolate due to their way of existence and diet. In the populations of the northwest coast of the Sea of Okhotsk and the Chukchi Peninsula, the SI delAG variant was brought by the gene flow from the Inuit people. © 2023. This work is licensed under a CC BY 4.0 license.

Introduction. Trehalose or mushroom sugar has been increasingly used in the food industry in the past decades. To be absorbed in the human intestine, trehalose needs to be broken down by an enzyme known as trehalase. Today, it is known that the G→A substitution in the rs2276064 locus of the TREH gene results in the reduced activity of this enzyme.

The aim of this study was to analyze the frequency of TREH (rs2276064) alleles and genotypes in the populations of South Siberia, Kazakhstan, Central Asia and Mongolia that differ in the contribution of the ancestral East Eurasian (Mongoloid) component to their gene pools.

Methods. We genotyped 987 DNA samples collected from the representatives of 17 indigenous populations from Siberia, Kazakhstan and Mongolia. The samples of 311 ethnic Russians comprised a reference dataset. In addition to estimating the frequencies of TREH alleles and genotypes, we analyzed the contribution of the ancestral East Eurasian (Mongoloid) and West Eurasian (European) ADMIXTURE components for the studied populations using an Illumina 750k microarray of SNP markers.

Results. The frequency of the A*TREH allele associated with trehalase deficiency increases from west to east (r_sp =0.500, p <0.05). TREH is correlated more strongly with the contribution of the ancestral East Eurasian (Mongolian) component than with the geography of the studied populations: r_sp =0.613 (p =0.007); with AA*TREH frequency r_sp =0.688 (p =0.002).

Conclusions. The rs2276064-А TREH allele is more frequent than previously estimated from clinical data. The more substantial is the contribution of the ancestral East Eurasian (Mongoloid) component, the higher is the frequency of the risk A*TREH allele, which rises dramatically to 29-30% in the Kyrgyz, Khakass, Tuvinian and 39% in Khalkha Mongol populations. Together, carriers of the AG and AA*TREH genotypes make up 35% to 65% of the populations of Oriental origin. We hypothesize that the high frequency of genetic trehalase deficiency determinants in the populations of Siberia, Kazakhstan, Central Asia, and Mongolia is associated with their anthropological characteristics and is not purely dependent on geographic factors.

© 2023. This work is licensed under a CC BY 4.0 license

Introduction. The authors consider the features of genetic determinants of disaccharide assimilation as the corollary of adaptation to the environment. The aim of the study was to assess the polymorphism of the genes that determine activity of disaccharidase enzymes lactase (LCT, rs4988235), trehalase (TREH, rs2276064) and sucrase-isomaltase (SI, rs781470490) in different territorial groups of Evenks.

Materials and methods. Biomaterial samples from 1365 unrelated individuals representing 15 ethno-territorial population groups in European Russia, Siberia, and the Far East of the Russian Federation were genotyped. "Focus" groups include "Western" (N=65), "Transbaikal" (N=50), and "Okhotsk" (N=81) Evenks (Krasnoyarsk Krai, Northern Transbaikalia, Okhotsk-Aldan region). The other study groups allow us to assess the specificity of the distribution of genetic determinants of disaccharide assimilation in populations that differ from racial, ecological, and subsistence perspectives.

Results. The Evenki territory subgroups do not differ from each other in terms of allele frequencies and genotype distribution of LCT (p>0.2) and TREH (p>0.8) and are similar to Yakuts, Buryats, Mongols, and populations of the Far East and Chukotka. The SI delAG deletion was not found in the Western Evenki subgroup.

Discussion. A question of similarity between taiga hunters Evenks to cattle breeders Buryats, Mongols, and Yakuts in terms of C*LCT frequencies requires further elaboration. Possible explanations may include a weakening of selection for the T*LCT allele due to the shift in traditional diet toward replacement of fresh milk with fermented dairy products, high activity of specific intestinal microflora, or the existence of other lactase synthesis genetic determinants, besides LCT*C/T-13910. The evolutionary origins of the clinal variation in the TREH gene allele frequencies, which appears to be associated with the expression of the Mongoloid ancestral component in the gene pool of populations in Northern Eurasia, remain unclear. It seems appropriate to conduct genetic screening in the indigenous populations of the Russian Far East in order to assess the prevalence of SI delAG deletion as an inducer of the sucrase-isomaltase deficiency. © 2024. This work is licensed under a CC BY 4.0 license

Introduction. Several studies have demonstrated a correlation between variations in genes regulating human uncoupling proteins (UCP) and environmental factors. However, information on the intra- and interpopulation diversity of allele and genotype frequencies of UCP1 and UCP3 within the territory of Russia remains insufficient. This study aims to investigate the intra- and inter-ethnic variability of genetic determinants of activity of uncoupling proteins UCP1 and UCP3, and to evaluate genotype-environment associations in the populations residing in the northeastern region of Russia.

Materials and methods. Genotyping was conducted on a total of 1,698 biological specimens collected from individuals representing 22 population groups of European Russia, Siberia, and the Russian Far East. Geographical and climatic data spanning from 1940 to 2023 were gathered for each sample collection locality.

Results and discussion. The spatial distribution of genetic determinants affecting the activity of UCP1 and UCP3 uncoupling proteins demonstrates a correlation with the severity of natural conditions. Three regression models of allele frequencies were constructed using climatic characteristics as predictors. All models are statistically significant (p<0.05 in all cases) and explain 39%, 36%, and 64% of the variability in UCP1 (rs6536991, rs1800592) and UCP3 (rs1800849) allele frequencies, respectively. These correlations revealed by the models confirm the adaptability of UCP genes in the indigenous population groups of Northern Eurasia.

Conclusion. The results of this study are consistent with the assumptions reported in scientific literature and significantly enhance existing knowledge. We observed correlations between allele and genotype frequencies of UCP1 (rs6536991, rs1800592) and UCP3 (rs1800849) genes and geographic latitude, elevation above sea level, as well as climatic indicators such as annual average rainfall, range of surface air temperatures, and the Bodman “weather severity” index. Further investigation involving a larger number of ethnic and territorial groups is necessary to better understand the factors influencing UCP gene variability formation. © 2024. This work is licensed under a CC BY 4.0 license