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The Tibetan-Yi Corridor, located on the eastern edge of the Tibetan Plateau, is the main route of the people of the plateau. Human settlement and diffusion along the corridor have played a pivotal role in shaping the genetic architecture of Sino-Tibetan-speaking (STs) populations in China. In this study, five STs groups (Chengdu Tibetan, Chengdu Han, Muli Tibetan, Lugu Lake Mosuo and Xichang Yi) settling in the Tibetan-Yi Corridor were genotyped via AGCU InDel 50 kit on the capillary electrophoresis platform to decrypt the genetic landscape and phylogenetic relationship of STs populations and investigate the forensic characteristics. Allele frequency distributions of all autosomal insertion/deletion polymorphisms (InDels) in studied groups comply with Hardy-Weinberg equilibrium. The combined power of discrimination values are 0.9999999999999999998, 0.9999999999999999995, 0.9999999999999999999, 0.999999999999999993 and 0.99999999999999999994, respectively, and all the combined probability of exclusion values exceed 0.9990. Forensically relevant statistics implied that these InDels could be used for individual identification and as a promising alternative to STR profiling in paternity testing. Typical population comparisons showed strikingly high homogeneity among studied STs people, indicating complicated genetic admixture among populations in the Tibetan-Yi Corridor. The STs groups in the Tibetan-Yi Corridor keep close genetic affinity with geographically or linguistically close populations, and the genetic components of investigated populations arose from a mixture of multiple ancestral gene pools (resulting from the admixture from the ancestral Highland Tibetans and ancestral Lowland indigenous populations).

Mitochondrial DNA (mtDNA) is a key player in numerous multifaceted and intricate biological processes and plays a pivotal role in dissecting the peopling of different populations, due to its maternally inherited property and comparatively high mutation rate. In this study, 119 Tibetan individuals from the Muli Tibetan Autonomous County of China (average altitude above 3,000 m) were employed in mitochondrial genome (mitogenome) sequencing by massively parallel sequencing (MPS) techniques using the Precision ID mtDNA Whole Genome Panel on an Ion S5XL system. The dataset presented 88 distinct haplotypes, resulting in the haplotype diversity of 0.9909. The majority of haplotypes were assigned to East Asian lineages and the distribution of haplogroups of Muli Tibetan significantly differed from reference Tibetan populations. The maximum parsimony phylogeny reconstructed by 119 newly generated mitogenomes revealed 12 major Muli Tibetan lineages. Intriguingly, a Sherpa-specific sub-haplogroup A15c1 with the lack of mutations at 4216 and 15,924 was discerned in our dataset, which suggested that the maternal gene pool of Sherpas may derive from Tibetan populations. The shared haplogroups between Muli Tibetan and lowland Han Chinese hinted that these lineages may derive from non-Tibetans and have already differentiated before their arrival on the Tibetan Plateau. Furthermore, extensive pairwise population comparisons displayed that Muli Tibetan had a closer genetic relationship with ethnically or linguistically close Nyingtri Tibetan, Nyingtri Lhoba and Chamdo Tibetan populations. Genetic affinity was also observed between the Muli Tibetan and North Han Chinese. Collectively, the results generated in this study enriched the existing forensic mtDNA database and raised additional interest in the application of whole mitogenome sequencing in forensic investigations., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Culturally diverse Tibetans (Ü-Tsang, Kham and Ando) harboring a unique molecular mechanism that allows them to successfully adapt to hypoxic environments in the Qinghai-Tibet Plateau have been a subject of great interest in medical genetics, linguistics, archeology and forensic science. However, forensic characteristics and genetic variations of the Y-chromosomal 27-marker haplotype included in the Yfiler Plus system in the Ü-Tsang and Kham Tibeto-Burman-speaking Tibetans remain unexplored. Thus, we genotyped 27 Y-STRs in 230 Shigatse Ü-Tsang Tibetans (SUT) and 172 Chamdo Kham Tibetans (CKT) to investigate the forensic characterization and genetic affinity of Chinese Tibetan Highlanders. The haplotype diversities were 0.999962028 in SUT and 0.999796002 in CKT. Forensic diversity measures indicated that this 27-Y-STR amplification system is appropriate for routine forensic applications, such as identifying and separating unrelated males in deficiency paternity cases, male disaster victims and missing person identification and determining male components in sexual assault cases. Moreover, the genetic relationships among 63 worldwide populations (16,282 individuals), 16 Asian populations, and 21 Chinese populations were analyzed and reconstructed using principal component analysis, multidimensional scaling plots and a phylogenetic tree. Considerable genetic differences were observed between Tibetan populations and other geographically/ethnically diverse populations (Han Chinese). Our studied SUT and CKT have a genetically closer relationship with Gansu Ando Tibetans than with other Asians. In total, our analyses indicated that subpopulation structures exist among Asian and Chinese populations, and population-specific reference databases should be established for forensic applications.