A genetic sub-structure study of the Tibetan population in Southwest China

Abstract

Tibetan is a typical ethnic minority population in Southwest China, which can be divided into U-Tsang, Kham, Amdo, Jiarong and other sub-populations. However, the genetic structure of these sub-populations has not been comprehensively analyzed, especially from the perspective of paternal and maternal lineages. Based on genetic markers of autosomes, the Y chromosome and mitochondria, we studied four Tibetan populations (the U-Tsang population in Tibet Autonomous Region; the Kham population in Garze, Sichuan province; the Amdo population in Qinghai province and the Jiarong population in Aba, Sichuan province) to interpret their genetic structure. The mini-sequencing technology was used to detect the genotype of each maker. Meanwhile, the PowerPlex ?Y23 and DNA Typer TM Y26 kit were applied to genotype Y-STRs. Subsequently, the genetic structure was analyzed by heatmap and principal component analysis, ancestry component, haplogroup frequency, network map and multi-dimensional scaling analysis. The results showed that the four Tibetan populations could be divided into three sets based on the autosomal and Y-chromosomal genetic markers, in which set 1 was the U-Tsang population in the Tibetan Plateau, set 2 comprised of the Kham and Amdo populations in the surrounding areas of the plateau, and set 3 was the Jiarong population that resided in the Tibetan and Yi Corridor. No significant difference was observed in mitochondrial genetic markers among four Tibetan populations. In general, multi-category genetic information provides a new comprehensive insight into the Tibetan sub-population.藏族为中国西南地区典型的少数民族,分为卫藏、康巴、安多和嘉绒等多个支系。然而,对藏族支系人群的遗传结构,特别是各分支人群的父系、母系遗传结构却缺乏深度解析。本研究基于个体水平的常染色体、父系来源的Y染色体和母系来源的线粒体3个类别遗传信息,对西藏地区卫藏藏族、四川甘孜地区康巴藏族、青海地区安多藏族和四川阿坝地区嘉绒藏族共4个藏族群体进行研究,以揭示其遗传亚结构关系。采用微测序技术检测各位点分型,利用PowerPlex ?Y23和DNATyper TM Y26试剂盒检测Y-STRs基因座分型,通过热图和主成分分析、祖先成分分析、单倍群频率统计、网络图及多维尺度分析等探讨其遗传亚结构。结果表明,常染色体和Y染色体遗传标记可将4个藏族人群分为3类：青藏高原的卫藏藏族为一类,高原周边地区的康巴藏族和安多藏族的遗传结构类似分为一类,“藏彝走廊”中嘉绒藏族的遗传结构与其他藏族人群差异显著而为一类。不同藏族分支人群在线粒体遗传信息方面无明显差异性。上述多类别遗传信息的分析结果为深入了解藏族不同分支人群的遗传亚结构提供了新视角。.