May 14, 2010

Genes Help Tibetans Survive In High Altitudes

Researchers have discovered the secret of how Tibetans are able to live comfortably in rarefied air at very high altitudes.

Scientists have found that Tibetans have a special genetic feature that allows them to breathe easy in higher places.  The researchers analyzed the genes of 31 Tibetans who were unrelated to each other, and compared them to the DNA of 90 Chinese and Japanese individuals living in low-lying areas.

The scientists from China and the U.S. wrote in a paper published in the journal Science on Friday that they hunted for genetic variations in locations that previous studies associated with adaptation to high altitudes.

Tibet is the highest region on Earth, with an average elevation of 16,000 feet.

Co-author Jinchuan Xing from the Eccles Institute of Human Genetics at the University of Utah School of Medicine in the U.S. said that two genes -- EGLN1 and PPARA on human chromosomes 1 and 22 -- turned up consistently.

"Their exact roles in high-altitude adaptation is unclear. Both EGLN1 and PPARA ... may cause a decrease of the hemoglobin concentration," Xing told Reuters.

Tibetans have unusually low blood hemoglobin levels, which allow them to thrive at high altitudes.  However, it is only now that experts have been able to trace this feature back to genes.

When people that live in lowlands visit Tibet, the lack of oxygen from the high altitude causes their bodies to get altitude sickness, which can develop into fatal heart or brain inflammation.

"Presumably Tibetans have developed a regulation mechanism to control the hemoglobin concentration to prevent these negative effects," Xing told Reuters.


On the Net: