Genetic polymorphism of Y-chromosome in Kazakh populations from Southern Kazakhstan

BACKGROUND

The Kazakhs are one of the biggest Turkic-speaking ethnic groups, controlling vast swaths of land from the Altai to the Caspian Sea. In terms of area, Kazakhstan is ranked ninth in the world. Northern, Eastern, and Western Kazakhstan have already been studied in relation to genetic polymorphism 27 Y-STR. However, current information on the genetic polymorphism of the Y-chromosome of Southern Kazakhstan is limited only by 17 Y-STR and no geographical study of other regions has been studied at this variation.

RESULTS

The Kazakhstan Y-chromosome Haplotype Reference Database was expanded with 468 Kazakh males from the Zhambyl and Turkestan regions of South Kazakhstan by having their 27 Y-STR loci and 23 Y-SNP markers analyzed. Discrimination capacity (DC = 91.23%), haplotype match probability (HPM = 0.0029) and haplotype diversity (HD = 0.9992) are defined. Most of this Y-chromosome variability is attributed to haplogroups C2a1a1b1-F1756 (2.1%), C2a1a2-M48 (7.3%), C2a1a3-F1918 (33.3%) and C2b1a1a1a-M407 (6%). Median-joining network analysis was applied to understand the relationship between the haplotypes of the three regions. In three genetic layer can be described the position of the populations of the Southern region of Kazakhstan-the geographic Kazakh populations of Kazakhstan, the Kazakh tribal groups, and the people of bordering Asia.

CONCLUSION

The Kazakhstan Y-chromosome Haplotype Reference Database was formed for 27 Y-STR loci with a total sample of 1796 samples of Kazakhs from 16 regions of Kazakhstan. The variability of the Y-chromosome of the Kazakhs in a geographical context can be divided into four main clusters-south, north, east, west. At the same time, in the genetic space of tribal groups, the population of southern Kazakhs clusters with tribes from the same region, and genetic proximity is determined with the populations of the Hazaras of Afghanistan and the Mongols of China.

Genetic polymorphism of 27 Y-STR loci in Kazakh populations from Eastern Kazakhstan

BACKGROUND

The establishment of a national haplotype database is important for forensic and genetic applications and requires studying genetic polymorphisms at Y-STR sites. However, the genetic structure of the Eastern Kazakhstan population is poorly characterised.

AIM

To investigate the genetic polymorphisms of 27 Y-STR loci in the Kazakh population from Eastern Kazakhstan and analyse the population genetic relationships of the Eastern Kazakhs with other populations.

SUBJECTS AND METHODS

The Yfiler Plus kit was utilised to genotype 246 healthy, unrelated males from Eastern Kazakhstan. Based on the raw data, haplotype and allele frequencies along with forensic parameters were calculated, and an MDS plot was constructed.

RESULTS

A total of 207 haplotypes were detected, of which 186 were unique. The haplotype diversity and discrimination capacity were 0.997 and 0.841, respectively. Population comparisons showed that Eastern Kazakhs have close genetic relationships with Kazakhs from Xinjiang, China. At the same time, a difference was found between the studied population and the previous one in the same part of Kazakhstan.

CONCLUSIONS

The obtained haplotypes will help to expand the Kazakhstan Y-chromosome reference database and will be useful for future genetic research and forensic applications.

Genetic Relationship Among the Kazakh People Based on Y-STR Markers Reveals Evidence of Genetic Variation Among Tribes and Zhuz

Ethnogenesis of Kazakhs took place in Central Asia, a region of high genetic and cultural diversity. Even though archaeological and historical studies have shed some light on the formation of modern Kazakhs, the process of establishment of hierarchical socioeconomic structure in the Steppe remains contentious. In this study, we analyzed haplotype variation at 15 Y-chromosomal short-tandem-repeats obtained from 1171 individuals from 24 tribes representing the three socio-territorial subdivisions (Senior, Middle and Junior zhuz) in Kazakhstan to comprehensively characterize the patrilineal genetic architecture of the Kazakh Steppe. In total, 577 distinct haplotypes were identified belonging to one of 20 haplogroups; 16 predominant haplogroups were confirmed by SNP-genotyping. The haplogroup distribution was skewed towards C2-M217, present in all tribes at a global frequency of 51.9%. Despite signatures of spatial differences in haplotype frequencies, a Mantel test failed to detect a statistically significant correlation between genetic and geographic distance between individuals. An analysis of molecular variance found that ∼8.9% of the genetic variance among individuals was attributable to differences among zhuzes and ∼20% to differences among tribes within zhuzes. The STRUCTURE analysis of the 1164 individuals indicated the presence of 20 ancestral groups and a complex three-subclade organization of the C2-M217 haplogroup in Kazakhs, a result supported by the multidimensional scaling analysis. Additionally, while the majority of the haplotypes and tribes overlapped, a distinct cluster of the O2 haplogroup, mostly of the Naiman tribe, was observed. Thus, firstly, our analysis indicated that the majority of Kazakh tribes share deep heterogeneous patrilineal ancestries, while a smaller fraction of them are descendants of a founder paternal ancestor. Secondly, we observed a high frequency of the C2-M217 haplogroups along the southern border of Kazakhstan, broadly corresponding to both the path of the Mongolian invasion and the ancient Silk Road. Interestingly, we detected three subclades of the C2-M217 haplogroup that broadly exhibits zhuz-specific clustering. Further study of Kazakh haplotypes variation within a Central Asian context is required to untwist this complex process of ethnogenesis.