Evolutionary significance of selected EDAR variants in Tibetan high-altitude adaptations

Jianming Shao, Muhammad Sohail Raza, Basang Zhuoma, Changqing Zeng

Humans have been exposed to many environmental challenges since their evolutionary origins in Africa and subsequent migrations to the rest of the world. A severe environmental challenge to human migrants was hypoxia caused by low barometric oxygen pressure at high altitudes. Several genome-wide scans have elucidated the genetic basis of human high-altitude adaptations. However, the dearth of functional variant information has led to the successful association of only a few candidate genes. In the present study, we employed a candidate gene approach and re-sequenced the EDAR locus in 45 Tibetan individuals to identify mutations involved in hypoxia adaptation. We identified 10 and five quantitative trait-associated mutations for oxygen saturation (SaO2) and blood platelet count, respectively, at the EDAR locus. Among these, rs10865026 and rs3749110 (associated with SaO2 and platelet count, respectively) were identified as functional candidate targets. These data demonstrate that EDAR has undergone natural selection in recent human history and indicate an important role of EDAR variants in Tibetan high-altitude adaptations.