Analyses Of The Matrilineal Inheritance Structure Of The Northern Tibeto-Burman Populations

MtDNA is a closed circular double stranded DNA molecule locating in the cytoplasm of eukaryote. Human mtDNA is composed of 16569 base pairs. It has two parts, the hypervariable region (control region) and the coding region. The former has more information sites. which is much helpful for tracing the historical events of human beings. According to historical documents, morden Tibeto-burman populations derived from primitive DiQiang tribe. Our previous data indicated that Northern Tibeto-burman population could be well represented the Tibeto-burman population. In order to clearly understand the maternal inheritance of the northern Tibeto-Burman populations, 272 whole genosome DNA samples were collected from 5 representative northern Tibeto-Burman areas including Qiangs in Sichuan, Baima Tibetans in Gansu and other Tibetan branches along Tibetan Plateau and its east side. Then mtDNA haplogroup was typed for every individual with SNaPshot technique and clustering analyses (dendrograms, principal component analyses and networks) were performed basing on our results and published data.As a result, the most frequent mtDNA haplogroup of Northern Tibeto-burman populations are A, C, D4, G, M9 and Z, which are much closed to the haplogroup of Janpanese, Northern Hans and Altaic language population. More interestingly, a very high frequency of haplogroup D was found in these groups, especially in Qiangs and Baima Tibetans (>30% and 20%, respectively). Combining the clustering analyses, our data suggested that Tibetan Plateau and its east side, is the diversity center for the mtDNA haplogroup D in Asia continent and even in the world. Other common mtDNA haplogroup networks also indicated that these five Tibeto-Burman groups are closed to the northern populations including Japanese in East Asia, in which, Qiang is the most ancient branch. In other words, Tibetans is much similar to the northern ethnic groups in maternal genetics and is a typical northern Mongoloid, although they live in the southwest in China where is quite far away from the North.