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Life-saving Tibetan Gene-ius

Tibet contains some of the world's tallest mountains including the tallest of all, Mount Everest. At 29,029ft it is over five miles high. It is very difficult to grasp how tall this is. Ben Nevis, the tallest mountain in the UK is 4,409ft tall. That's not even a pimple by Tibetan standards. Helicopters can't fly at this altitude; the air is so thin their blades can't get a grip. So how do the Tibetan people living that high up survive?

Living the high life – literally!

On average Tibet lies at an altitude of 16,500ft. The tallest mountain in the Alps, Mont Blanc, is only 15,781ft tall. Living at altitude presents the body with challenges.

The Alps

The amount of oxygen in the air is much lower than at sea level. To compensate for this the human body pulls a really neat trick, it tells the bone marrow to produce more red blood cells. More red blood cells mean it is easier for the blood to transport oxygen to different parts of the body. This is why athletes that compete in endurance events often train at altitude. If your body makes more red blood cells, when you come back down to sea level to compete, it can keep supplying the muscles with oxygen for longer.

EPO

The banned substance called EPO does the same thing. A quick injection under the skin and the bone marrow goes into overdrive. It can be very hard to detect with a dope test because altitude training has exactly the same effect and is perfectly legal.

The down side

If the body produces too many red cells things can go horribly wrong. The blood becomes very thick and goopy. It can be very difficult for the heart to pump it around. It has proven lethal in the past when athletes have taken too much EPO and died in their sleep. When the heart slows down there is not enough pressure to pump the red blood cell sludge that the blood becomes.

Long term exposure can also lead to swelling of the lungs and brain, and damage to the blood vessels. Many mountaineers die of these complications every year as they try to conquer the world's tallest peaks. Even people who live and work at altitudes higher than their normal can become very ill. It happened to some of the celebrities who conquered Killamanjaro for Comic Relief, remember? That's what happens to us sea level dwellers anyway. If you are a Tibetan you simply don't encounter these problems. The big question has always been why?

The Tibetan Gene

Researchers have found that even at these extreme altitudes Tibetans do not overproduce red blood cells and yet their blood can still carry the extra oxygen needed to thrive. It seems that Tibetans have evolved genes that are unique to them.

Cells

There are about ten genes that seem to be involved closely with this adaption. Two of the genes affect haemoglobin directly. Haemoglobin is the chemical present in red blood cells that actually carries the oxygen. It makes up about 97 per cent of a blood cells dry weight so it is a red blood cell's most important bit!

Tibetans appear to have developed more efficient metabolisms. They show higher levels of nitric oxide in their blood, this seems to allow them to get more oxygen to the tissues without producing lots more red cells. The mechanism is not well understood yet, but could prove to be very important.

Heart Disease

Why could it be important?

200,000 people every year die from cardiovascular disease. Heart disease affects over 1.1 million Britons alone. It is one of the world's great killers. Just imagine you could persuade a human body to live happily with a smaller amount of red blood cells. The heart would not have to work nearly as hard.

It could be given time to recover. The effect of blocked or furred up arteries could be reduced. In principle it could contribute to saving the lives of millions. There is still much work to be done but this bit of research could prove to be very valuable to an awful lot of people.

The big questions:

What challenges do living at altitude hold?

How do people adapt to living at altitude?

What roll do genes play?

How can understanding high-altitude genetics help the rest of us?