Less is more: Tibetans thrive on 'roof of the world' due to missing genome, study suggests
Tibetan highlanders may have adapted to their high altitude environment by breeding out parts of the genetic code over thousands of years, according to a new Chinese study.
This genetic mutation stabilised their red blood cell count, thus keeping altitude sickness, and more deadly side effects linked to great heights, at bay, the scientists believe.
Tibetans have lived on the roof of the world for thousands of years, an extreme environment where snow capped peaks tower over 7,000 metres, and Himalayan Sherpas earn a living by ferrying loads up mountains.
Usually, red blood cells spike at higher elevations, an emergency response that increases the lungs’ ability to absorb oxygen from the air.
But most Tibetans have “normal” readings, and now scientists think a mutation dubbed TED, short for Tibetan-enriched deletion, is the key.
Data analysis showed that the mutation caused the deletion of a specific genome section near the gene EPAS1.
“TED might have played a critical role in the high altitude adaptation of Tibetans,” said professor Xu Shuhua, lead scientist of the study.
He described the find as a springboard for future studies. Xu is a researcher with the Chinese Academy of Sciences’ Shanghai Institute for Biological Sciences.
The team published their results in the latest issue of the American Journal of Human Genetics.
Prior to this, it was believed that Tibetans had somehow acquired a “super gene” to help them adapt to thinner air. Many candidates were suggested, including EPAS1.
But Xu’s team developed a more elaborate hypothesis after discovering that nine in 10 native Tibetans have certain genetic copies missing from their DNA. This is incredibly rare elsewhere in the world, only affecting 3 per cent of people.
The findings were not conclusive, however. Xu said it could take several years of extensive animal trials to confirm the theory.
Moreover, the study was complicated by the fact that the deleted sequence could not be detected by routine methods, Xu said.
After years of persevering, the team developed a new approach that could efficiently detect copy number variations specific to a particular population, which led to the discovery, it said.