POSTER NO: 188

Study on Multiple Origins of Tibetan using Y Chromosomes SNP Markers

¹Yaping Qian, ¹Jiayou Chu, ³Bing Su, ²Li Jin
¹Institute of Medical Biology, Chinese Academy of Medical Sciences, Kunming, 650118, China, ²Institute of Genetics, Fudan University, Shanghai, China, ³Human Genetics Center, University of Texas-Houston, Houston, Texas

The genetic origin of Tibetans was investigated using 19 Y chromosome single nucleotide polymorphic (SNP) markers. Three Tibetan populations, two from central Tibet (Lhasa and Shigatse), and the other one from Zhongdian (northwestern Yunnan) were sampled. The former populations are called Zang (Tsang) who speak Tibetan belonging to the Central Tibetan branch, while the latter is called Khamba who speak Kham, a northern Tibetan language. In the three Tibetan populations, 10 Y haplotypes were observed. No significant difference between the Lhasa and Shigatse peoples was observed. It is clear that both Zang and Khamba populations are predominated by two haplotype groups defined by the YAP+ (H2 and H3) and M122C (H6 and H8), encompassing about 80% of their gene pools and suggesting a common origin of those two populations. The YAP+ was an ancient polymorphism originated from Central Asia and made major contributions to Tibetan populations (41.3% in Zang and 44.4% in Khamba). Our previous study on extant East Asian populations demonstrates that M122C (defining H6, H7 and H8) is predominant in East Asian populations, especially in Han Chinese (54.1% on average), but it is merely absent in other world populations, including Central Asians . Therefore, the high frequency of M122C in Tibetan population (>35%) reflects a genetic source originated from East Asian populations where YAP+ is virtually absent. In conclusion, Tibetan Y-chromosomes may have been derived from two different gene pools, one from Central Asia and the other from East Asia.