In an environment where others struggle to survive, Tibetans thrive in the thin air on the Tibetan Plateau, with an average elevation of 14,800 feet. A study led by University of Utah scientists is the first to find a genetic cause for the adaptation–a single DNA base pair change that dates back 8,000 years–and demonstrate how it contributes to the Tibetans’ ability to live in low oxygen conditions. The study appears online in the journal Nature Genetics on Aug. 17, 2014.
“These findings help us understand the unique aspects of Tibetan adaptation to high altitudes, and to better understand human evolution,” said Josef Prchal, M.D., senior author and University of Utah professor of internal medicine.
First author Felipe Lorenzo, Ph.D., spent years combing through the Tibetans’ DNA, and unlocking secrets from a “GC-rich” region that is notoriously difficult to penetrate. His hard work was worth it, for the Tibetans’ DNA had a fascinating tale to tell. About 8,000 years ago, the gene EGLN1 changed by a single DNA base pair. Today, a relatively short time later on the scale of human history, 88% of Tibetans have the genetic variation, and it is virtually absent from closely related lowland Asians. The findings indicate the genetic variation endows its carriers with an advantage.
Prchal collaborated with experts throughout the world to determine what that advantage is. In those without the adaptation, low oxygen causes their blood to become thick with oxygen-carrying red blood cells–an attempt to feed starved tissues–which can cause long-term complications such as heart failure. The researchers found that the newly identified genetic variation protects Tibetans by decreasing the over-response to low oxygen.
These discoveries are but one chapter in a much larger story. The genetic adaptation likely causes other changes to the body that have yet to be understood. Plus, it is one of many as of yet unidentified genetic changes that collectively support life at high altitudes.