Y-STR markers from Ladakh in the Himalayas

The maternal genetic origin and diversity of the extant populations of the Ladakh region in India

Ladakh lies at a strategic location between the Indus River valley and the Hindu Khush Mountains, which makes the "Land of high passes" one of the major routes of movement. Through the years the region has faced multi-layered cultural movements, genetic assimilation and demographic changes. The initial settlement in the years goes back to the early Neolithic age and still continues despite its harsh, unhospitable and cold climate. Previous studies mostly covered the patrilineal markers of the region and an in-depth study lacked to represent the matrilineal ancestry and possible genetic inflow in the region. Hence, our current study first time generated complete mitogenomes of 108 unrelated individuals from Ladakh belonging to three population groups namely, Changpa (n = 38), Brokpa (n = 32) and Monpa (n = 38). In the in-depth analysis, we found that the mitogenome of the three Ladakhi groups are highly diverse in terms of maternal haplogroup distribution carrying lineages specific to East Asia (M9a), Tibbet (A21) and South Asia (M3, M30, U2). In our analysis we found that Changpa and Monpa probably have shared maternal ancestry compared to Brokpa, which is very distinct and also later suffered possible historical Bottleneck. Bayesian evolutionary and Network analysis indicates more ancient maternal lineage of Changpa and Monpa in terms of M9a haplotypes, but they also share some genetic history with Tibeto-Burman speakers in past. These findings conclusively indicate possible matrilineal genetic inflow in Ladakh from three directions, primarily from East Asia or South East Asia during post-glacial, West Eurasia and also from South Asia.

Y-23 mediated genetic data analysis of endogamous Brahmin population of Rajasthan, India

India's largest state Rajasthan is known for its variable population groups including castes, communities and tribes. In the present article, Y-STR polymorphisms of hundred unrelated healthy male volunteers from the Brahmin population of Rajasthan, India were investigated using the Powerplex® Y-23 PCR amplification kit. Total 94 distinct haplotypes were obtained out of them 93 were singletons. Haplotype Diversity (HD) and Discrimination Capacity (DC) for the population were 0.644 and 0.9894 respectively. The Intra-population relationship between the present population data and other reported Indian populations was examined through Multidimensional Scaling (MDS) Plot, which shows the Brahmin population of Rajasthan lies in a cluster with the Brahmin populations of Haryana and Maharashtra. Data generated with 23 Y-STR markers is submitted on Y chromosome haplotype reference database (YHRD) (yhrd.org) and it will robust the forensic database of the Rajasthan population of India.

Investigating the genetic diversity and affinities of historical populations of Tibet

This study elucidates Y chromosome distribution patterns in the three general provincial populations of historical Tibet, Amdo (n = 88), Dotoe (n = 109) and U-Tsang (n = 153) against the backdrop of 37 Asian reference populations. The central aim of this study is to investigate the genetic affinities of the three historical Tibetan populations among themselves and to neighboring populations. Y-SNP and Y-STR profiles were assessed in these historical populations. Correspondence analyses (CA) were generated with Y-SNP haplogroup data. Y-STR haplotypes were determined and employed to generate multidimensional scaling (MDS) plots based on Rst distances. Frequency contour maps of informative Y haplogroups were constructed to visualize the distributions of specific chromosome types. Network analyses based on Y-STR profiles of individuals under specific Y haplogroups were generated to examine the genetic heterogeneity among populations. Average gene diversity values and other parameters of population genetics interest were estimated to characterize the populations. The Y chromosomal results generated in this study indicate that using two sets of markers (Y-SNP, and Y-STR) the three Tibetan populations are genetically distinct. In addition, U-Tsang displays the highest gene diversity, followed by Amdo and Dotoe. The results of this transcontinental biogeographical investigation also indicate various degrees of paternal genetic affinities among these three Tibetan populations depending on the type of loci (Y-SNP or Y-STR) analyzed. The CA generated with Y-SNP haplogroup data demonstrates that Amdo and U-Tsang are closer to each other than to any neighboring non-Tibetan group. In contrast, the MDS plot based on Y-STR haplotypes displays Rst distances that are much shorter between U-Tsang and its geographic nearby populations of Ladakh, Punjab, Kathmandu and Newar than between it and Amdo. Moreover, although Dotoe is isolated from all other groups using both types of marker systems, it lies nearer to the other Tibetan collections in the Y-SNP CA than in the Y-STR MDS plot. High resolution and shallow evolutionary time frames engendered by Y-STR based analyses may reflect a more recent demographic history than that delineated by the more conserved Y-SNP markers.