[Genetically determined trehalase deficiency in various population groups of Russia and neighboring countries].

Due to the low specificity and sensitivity of non-invasive clinical tests trehalose malabsorption remained out of sight of gastroenterologists. Therefore, the specialists regard this disorder as rare. Trehalose became widely used in the food industry as a harmless sucrose substitute, sweetener and stabilizer. After the discovery of the trehalase gene (rs2276064 TREH), it was found that the A*TREH allele is the determinant of the disaccharide absorption disorders, and the allele's carriership may be high in some groups. There is not enough information on the A*TREH frequency in the population of Russia. The aim of the study was to analyze the allele and genotype frequencies of the trehalase gene (rs2276064 TREH) in the main population groups of the Russian Federation and neighboring countries. Methods. DNA samples from 1146 unrelated subjects belonging to 21 population groups of Russia, Azerbaijan, Tajikistan and Mongolia were genotyped by the two following methods: 1) using the Infinium iSelect HD Custom Genotyping BeadChip (Illumina, USA) on the iScan platform; 2) by the real time polymer-chain reaction (PCR) method on the Bio-Rad CFX96 Touch amplifier. Results. It has been found that on the territory of the Russian Federation the frequency of the A*TREH allele increases from the west to the east. The frequencies are lowest in the groups of Russians and Finns of the Northwest (0.01-0.03), up to 0.07 in the populations of Central Russia and the Volga region, and even higher toward the Southern Urals (Bashkirs 0.15), in the Transurals and Southern Siberia (0.19 in the Altai people, 0.30 in the Tuvinians and Mongols). Up to 1% of the population of the European part of the Russian Federation have the AA*TREH genotype (i.e. trehalose intolerance in phenotype), and up to 15% (GA*TREH genotype) have a reduced ability to absorb the disaccharide. In the Asian part of the country (Siberia, Altai, Baikal) the genotypes carriers constitute up to 12 and 46% respectively. Conclusion. Trehalose malabsorbtion is an underappreciated problem of particular practical importance for regions with high concentrations of indigenous population (Yakutia-Sakha, Buryatia, Tyva, etc.). It would be feasible to consider food labelling of trehalose.

[Gene pool of Siberian Tatars: Five ways of origin for five subethnic groups].

Siberian Tatars form the largest Turkic-speaking ethnic group in Western Siberia. The group has a complex hierarchical system of ethnographically diverse populations. Five subethnic groups of Tobol-Irtysh Siberian Tatars (N = 388 samples) have been analyzed for 50 informative Y-chromosomal SNPs. The subethnic groups have been found to be extremely genetically diverse (FST = 21%), so the Siberian Tatars form one of the strongly differentiated ethnic gene pools in Siberia and Central Asia. Every method employed in our studies indicates that different subethnic groups formed in different ways. The gene pool of Isker-Tobol Tatars descended from the local Siberian indigenous population and an intense, albeit relatively recent gene influx from Northeastern Europe. The gene pool of Yalutorovsky Tatars is determined by the Western Asian genetic component. The subethnic group of Siberian Bukhar Tatars is the closest to the gene pool of the Western Caucasus population. Ishtyak-Tokuz Tatars have preserved the genetic legacy of Paleo-Siberians, which connects them with populations from Southern, Western, and Central Siberia. The gene pool of the most isolated Zabolotny (Yaskolbinsky) Tatars is closest to Ugric peoples of Western Siberia and Samoyeds of the Northern Urals. Only two out of five Siberian Tatar groups studied show partial genetic similarity to other populations calling themselves Tatars: Isker-Tobol Siberian Tatars are slightly similar to Kazan Tatars, and Yalutorovsky Siberian Tatars, to Crimean Tatars. The approach based on the full sequencing of the Y chromosome reveals only a weak (2%) Central Asian genetic trace in the Siberian Tatar gene pool, dated to 900 years ago. Hence, the Mongolian hypothesis of the origin of Siberian Tatars is not supported in genetic perspective.