Exceptional longevity results from favourable genes much more than from a healthy lifestyle and environment, according to the first extensive genetic analysis of people who lived past the age of 100.
Researchers at Boston University have identified 150 genetic variants that, taken together, can predict exceptional longevity with 77 per cent accuracy.
The scientists compared the genomes of 1,055 centenarians with a similar number of control subjects, using DNA-scanning technology. They distilled the differences down to 150 life-extending changes, each affecting one chemical “letter” in the 3bn letters of the human genetic code.
These changes run right across the human genome. A few affect genes associated with age-related diseases, such as the ApoE and Alzheimer’s but many have unknown functions.
“Longevity is an extremely complex genetic trait involving many biological processes,” said Thomas Perls, co-author of the paper and director of the New England Centenarian Study. “We’re a long way from understanding them.”
The research confirmed that there could be no simple “elixir” to extend life, he added.
The scientists were surprised to find that, on the whole, the centenarians did not have fewer genetic variants known to trigger disease than the controls.
“What makes a difference is more the positive enriching effect of genetic variants that protect against disease than the absence of disease-associated variants,” said Dr Perls.
Although the details remain a mystery, what seems to happen as people age is that lifestyle and environment – such as healthy eating, exercising and avoiding smoking and obesity – are important in determining lifespan up to the 80s. After that, genes play an increasingly important role.
DNA rather than lifestyle is almost entirely responsible for generating “super-centenarians” who survive beyond 110. They make up one in 7m people in the industrial world.
Eighty-five per cent of centenarians and 90 per cent of super-centenarians are women. In spite of claims of people living to 140 or 150 in places from the Andes to the Caucasus, Jeanne Calment, who died in France in 1997 at the age of 122, remains the world’s oldest documented person.
Paola Sebastiani, professor of biostatistics at Boston University, said all data from the longevity study would be available without restrictions. “We have no financial interests in it and we are not planning to patent anything here,” she said.
Researchers will put up a web page this month where people can calculate their prospect of longevity. They also expect companies that sell genetic tests to consumers quickly to include a longevity assessment.
Source : Financial Times. July 1st.2010
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