Long life in genes

Want to live to be 100? Pick old grandparents.

It's an old irony, but researchers have said they have shown this is remarkably true when it comes to surviving into old age, and they believe a cluster of just a few genes may be responsible.

They have set up a company that studies centenarians to see if the genetic secret to living a long and healthy life may result in drugs that can prevent the diseases of ageing, such as Alzheimer's and heart disease.

"It isn't really that obvious," said Dr Thomas Perls, who led the study at Harvard University.

"It isn't old age that runs in families. It's exceptional old age that runs in families.

"We think this may be a handful of genes that could be playing really substantial roles in the ability to get to very old age, much of it in good health."

Perl's team studied 444 families, including more than 2000 relatives of people who lived to 100.

They compared this data with the 1900 census and the Social Security Administration's database, and found that brothers of centenarians were 17 times more likely than other people to reach the milestone themselves, and sisters were eight times as likely.

Earlier work has shown many of these people share similarities in their DNA, especially on chromosome 4. Perls hoped that his company, Centagenetix, could home in on the important genes and perhaps make discoveries that would lead to drugs that can stave off disease.

"Discovering these genes will lead to understanding the biochemical pathways that those genes affect," he said. "My hope is that that would help a lot of other people age more slowly and delay and, my goodness even escape, something like Alzheimer's."

Which genes you do not have may be as important as those you do, Perls said. For instance, he found the 100-year-olds were very unlikely to have a version of a gene called APOE-4, which is associated with high cholesterol and Alzheimer's.

Environment did not seem to be too important to those who lived to be 100. Census Bureau data showed they were more likely to be poor and poorly educated - something not usually associated with old age.

But for most of us, environment and behaviour is the key.

"I think the average set of genes gets us to our mid- to late-80s," said Perls, a geriatrician who now works at the Boston Medical Centre.

"I base this on twin studies and on Seventh Day Adventists, who have a life expectancy of 87 years, who do everything right - they don't smoke, they are lean, they are vegetarian, they exercise and, as a result, they live 10 years longer than the rest of us. That basically tells us what our genes are capable of.

"But to live the extra 15, 20 years beyond that, I suspect genes are playing a greater role."

- REUTERS

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