Li Qian, Lin Keqin, Sun Hao, Liu Shuyuan, Huang Kai, Huang Xiaoqin, Chu Jiayou, Yang Zhaoqing
Department of Medical Genetics, Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Yunnan, China.
J Hum Genet. 2016 Dec;61(12):1021-1026. doi: 10.1038/jhg.2016.95. Epub 2016 Jul 28.
While hypoxic environment at high altitude remains a major challenge for travelers from low-altitude areas, Tibetans have adapted to the high-altitude environment. Mitochondria are the energy conversion and supplement centers in eukaryotic cells. In recent years, studies have found that the diversity of the mitochondrial genome may have a role in the adaptation to hypoxia in Tibetans. In this study, mitochondrial haplogroup classification and variant genotyping were performed in Tibetan and Han Chinese populations living at different altitudes. The frequencies of mitochondrial haplogroups B and M7 in the high-altitude population were significantly lower compared with those in the low-altitude population (P=0.003 and 0.029, respectively), whereas the frequencies of haplogroups G and M9a1a1c1b in the high-altitude group were significantly higher compared with those in the low-altitude group (P=0.01 and 0.002, respectively). The frequencies of T3394C and G7697A, which are the definition sites of haplogroup M9a1a1c1b, were significantly higher in the high-altitude group compared with that in the low-altitude group (P=0.012 and 0.02, respectively). Our results suggest that mitochondrial haplogroups B and M7 are associated with inadaptability to hypoxic environments, whereas haplogroups G and M9a1a1c1b may be associated with hypoxic adaptation. In particular, the T3394C and G7697A variants on haplogroup M9a1a1c1b may be the primary cause of adaptation to hypoxia.
尽管高海拔地区的低氧环境对来自低海拔地区的旅行者来说仍然是一个重大挑战，但藏族人已经适应了高海拔环境。线粒体是真核细胞中的能量转换和补充中心。近年来，研究发现线粒体基因组的多样性可能在藏族人对低氧的适应中发挥作用。在本研究中，对生活在不同海拔高度的藏族和汉族人群进行了线粒体单倍群分类和变异基因分型。高海拔人群中线粒体单倍群B和M7的频率与低海拔人群相比显著降低（分别为P = 0.003和0.029），而高海拔组中单倍群G和M9a1a1c1b的频率与低海拔组相比显著升高（分别为P = 0.01和0.002）。作为单倍群M9a1a1c1b定义位点的T3394C和G7697A的频率在高海拔组中比低海拔组显著更高（分别为P = 0.012和0.02）。我们的结果表明，线粒体单倍群B和M7与对低氧环境的不适应性相关，而单倍群G和M9a1a1c1b可能与低氧适应相关。特别是，单倍群M9a1a1c1b上的T3394C和G7697A变异可能是适应低氧的主要原因。
