Tibetans' unique ability to survive at high altitudes deciphered

An international team of researchers, including two Indians, has discovered an 8,000-year-old gene mutation that gives Tibetans the unique ability to thrive in a low-oxygen climate, without exhibiting standard biological responses.

Because of a specific gene mutation, Tibetans thrive at an average elevation of 14,800 feet on the Tibetan plateau, while others struggle to cope in the same conditions. The mutation exists in about 88 per cent of Tibetans, but is virtually absent in other closely related low-land Asians.

“Our paper explains why Indians, Caucasians and Chinese do poorly at high altitudes because their organs overreact to the low oxygen levels,” team leader Josef T Prchal at the University of Utah told Deccan Herald.

This report is the first to identify and functionally characterise the genetic basis of adaptation at high altitudes. In 2010, the team had found that there were marked differences in the Tibetan genome, but had not pinpointed the specific gene.

In the latest issue of Nature Genetics, the scientists have reported the discovery of the specific “HIF” mutation in the EGLN1 gene, which is a single DNA base-pair change that short-circuits a potentially fatal response to low oxygen levels.

The 8,000-year-old mutation prevents Tibetans from developing hypoxia, a deadly condition exhibited by people without an adaptation mechanism. A low-oxygen environment leads to the thickening of blood due to the accumulation of red blood cells – the normal biological response to feed oxygen-starved tissues – which can lead to long-term complications such as heart failure.

The two Indian team members in the team, Prasenjit Guchhait from the Regional Centre on Biotechnology in Faridbad and Parvaiz A Koul from Sher-i-Kashmir Institute of Medical Sciences in Srinagar, were involved in collecting blood samples and carrying out DNA analysis for the study.

The Tibetans had initially refused to donate their blood for research. But after a letter of support from the Dalai Lama and the inclusion of a Tibetan scholar in the team, they agreed to cooperate with the scientists.

The results of this study could be just the beginning of further discoveries in the Tibetan genome, according to geneticist Samir K Brahmachari, former director-general of the Council of Scientific and Industrial Research.

“While the results are interesting, the sample sizes are small. The possibility of other mechanisms cannot be ruled out at this stage,” said Brahmachari.