Genetic structure of Tibetan populations in Gansu revealed by forensic STR loci

Hong-Bing Yao,Qiongying Deng,Bingying Xu,Qiajun Du,Xiaolan Tao,Hong-Dan Wang,Shao-Qing Wen,Shujin Li,Bin Cong Bin Cong,Chuan-Chao Wang,Ying Huang,Lei Shang,Liying Ma,Li Jin,Jiang Wang,Hui Li,Johannes Krause

doi:10.1038/srep41195

Abstract

The origin and diversification of Sino-Tibetan speaking populations have been long-standing hot debates. However, the limited genetic information of Tibetan populations keeps this topic far from clear. In the present study, we genotyped 15 forensic autosomal short tandem repeats (STRs) from 803 unrelated Tibetan individuals from Gansu Province (635 from Gannan and 168 from Tianzhu) in northwest China. We combined these data with published dataset to infer a detailed population affinities and genetic substructure of Sino-Tibetan populations. Our results revealed Tibetan populations in Gannan and Tianzhu are genetically very similar with Tibetans from other regions. The Tibetans in Tianzhu have received more genetic influence from surrounding lowland populations. The genetic structure of Sino-Tibetan populations was strongly correlated with linguistic affiliations. Although the among-population variances are relatively small, the genetic components for Tibetan, Lolo-Burmese, and Han Chinese were quite distinctive, especially for the Deng, Nu, and Derung of Lolo-Burmese. Han Chinese but not Tibetans are suggested to share substantial genetic component with southern natives, such as Tai-Kadai and Hmong-Mien speaking populations, and with other lowland East Asian populations, which implies there might be extensive gene flow between those lowland groups and Han Chinese after Han Chinese were separated from Tibetans. The dataset generated in present study is also valuable for forensic identification and paternity tests in China.

Highlights

During the past two decades, genetic evidence, especially from the maternal mitochondrial DNA and the paternal Y chromosome, has shed more light on the history of Sino-Tibetan populations
Tibeto-Burman populations tend to cluster with North Asian and Tai-Kadai populations rather than Han Chinese based on the frequency data of 15 autosomal short tandem repeats (STRs)[14]
The loci in both populations were highly discriminating with discrimination power (DP) ranging from 0.852 to 0.974, demonstrating that those loci are useful for forensic identification

Summary

Introduction

During the past two decades, genetic evidence, especially from the maternal mitochondrial DNA (mtDNA) and the paternal Y chromosome, has shed more light on the history of Sino-Tibetan populations. Y chromosome suggested Tibeto-Burman populations are an admixture of the northward migrations of East Asian initial settlers with haplogroup D-M175 in the Late Paleolithic age, and the southward Di-Qiang people with dominant haplogroup O3a2c1*-M134 and O3a2c1a-M117 in the Neolithic Age[6,7,8]. Tibeto-Burman populations tend to cluster with North Asian and Tai-Kadai populations rather than Han Chinese based on the frequency data of 15 autosomal short tandem repeats (STRs)[14]. A genome-wide study of PanAsia SNP project reveals that Han Chinese populations show varying degrees of admixture between a northern Altaic cluster and a Sino-Tibetan/ Tai-Kadai cluster[15]. The limited markers of mtDNA and Y chromosome and small sample sizes and insufficient sampling of genome-wide study are far from enough to give a comprehensive understanding about the genetic history and admixture process of Sino-Tibetan populations. We analyze 15 autosomal STRs in 635 and 168 unrelated individuals from two Tibetan populations in Gannan and Tianzhu of Gansu province to explore the genetic structure of Tibetan populations in northwest China and to test population affinities and the level of admixture of Sino-Tibetan populations with surrounding populations

Methods

Results

Conclusion