Two genes that help adapt the human body to high-altitude living have been identified by a study published in Science this month. The study may help scientists understand heart and lung disease where patients have decreased oxygen levels.
US and Chinese scientists analysed the DNA of 75 highland-dwelling Tibetans and compared it to the DNA of 90 lowland-dwelling Chinese and Japanese people. Variants in two genes involved in oxygen processing - EGLN1 and PPARA - were found to be more prevalent in the highland-dwelling Tibetans.
'This is a groundbreaking paper. These genes seem to have relatively large phenotypic effects', said Professor Anna Di Rienzo, a geneticist at the University of Chicago who was not involved in the study.
Tibetans who inherited two copies of the EGLN1 and PPARA gene variants were found to have lower blood oxygen levels and to use this oxygen more efficiently than those who inherited one or no copies of these variants.
Highland-dwelling people, such as the Andeans, have adapted to high altitudes by increasing their haemoglobin levels, thereby increasing their blood oxygen levels. Research suggests, however, that Tibetans have lower than average haemoglobin levels, making their blood less viscous and less prone to the health problems associated with increased viscosity.
'For the first time we have genes that explain that adaptation', said Professor Lynn Jorde who led the study at the University of Utah School of Medicine. 'Both EGLN1 and PPARA…may cause a decrease of haemoglobin concentration', said Dr Jinchuan Xing, who was also involved in the study.
Professor Jorde goes on to say that 'Just lowering your haemoglobin alone would make you less well adapted to high altitude'. Further research is therefore required to uncover how the Tibetans use the lower levels of oxygen in their blood so effectively, and the role played by EGLN1 and PPARA in this.
Professor Hugh Montgomery, director of the University College London Institute for Human Health and Performance, told the BBC 'It is important clinically because it helps us understand how patients cope with low oxygen levels…There are opportunities here for developing new drug therapies'.