title: Mitochondrial haplogroup M9a1a1c1b is associated with hypoxic adaptation in the Tibetans.
abstract: 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.
authors.affiliation: Department of Medical Genetics, Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Yunnan, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Li
authors.affiliation: Department of Medical Genetics, Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Yunnan, China.
authors.forename: Keqin
authors.initials: K
authors.lastname: Lin
authors.affiliation: Department of Medical Genetics, Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Yunnan, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Sun
authors.affiliation: Department of Medical Genetics, Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Yunnan, China.
authors.forename: Shuyuan
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Medical Genetics, Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Yunnan, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Huang
authors.affiliation: Department of Medical Genetics, Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Yunnan, China.
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Huang
authors.affiliation: Department of Medical Genetics, Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Yunnan, China.
authors.forename: Jiayou
authors.initials: J
authors.lastname: Chu
authors.affiliation: Department of Medical Genetics, Institute of Medical Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Yunnan, China.
authors.forename: Zhaoqing
authors.initials: Z
authors.lastname: Yang
mesh_terms: D000220:Adaptation, Biological / Q000235:genetics*; D000483:Alleles; D000531:Altitude; D004272:DNA, Mitochondrial; D050259:Genes, Mitochondrial; D056726:Genetic Association Studies; D014644:Genetic Variation; D005838:Genotype; D006239:Haplotypes; D006801:Humans; D000860:Hypoxia / Q000235:genetics*; D008928:Mitochondria / Q000235:genetics* / Q000378:metabolism; D020641:Polymorphism, Single Nucleotide; D018609:Tibet
chemical_list: D004272:DNA, Mitochondrial