[轉載]Study says about 15% of people have genetic profile for long

Only about 1 in 6,000 people will live past 100.

So at 102, West Palm Beach retiree Lillian Horowitz has become accustomed to answering the question, "What's the secret to long life?"

"I tell them, 'The important things in life are love and good friends,' " Horowitz said. "I never smoked and I never drank. I led a clean life."

A study published in Thursday's online edition of the journal Science found that achieving exceptional longevity may require something else: good genes.

Using a statistical method called genome-wide association, researchers looked at gene variants from more than 1,000 centenarians and a similar number of controls. They found 150 markers, grouped into 19 different profiles, which appeared to set the elders up for a long, healthy lives. Some of the profiles were associated with many years of life, others with late onset of debilitating disease.

Most of the centenarians had the same disease-linked genes, such as those for dementia and high blood pressure, as the general population. But their longevity genes appeared to protect them. Related studies have found that while centenarians still get illnesses such as cancer and heart disease, many get them much later than average.

The research suggests certain genes might actually cancel the risk of disease-linked genes, said Tom Perls, director of the New England Centenarian Study at Boston Medical Center and a lead author of the study, titled Genetic Signatures of Exceptional Longevity in Humans.

The findings throw into question the value of some commercial genetic tests for susceptibility to disease, he said.

"Your calculation of risk of disease may be incomplete if the other genetic background is ignored," Perls said. "Until these kits can take into account these complexities, I think they are not ready for prime time."

Horowitz said the findings ring true with her. At 102, she moved into assisted living at Morse­Life's Tradition of The Palm Beaches only a few months ago. Aside from arthritis and other frustrations, she's in good health. She takes few medications. She went without glasses until her 60s and didn't get dentures until she hit 100. She credits her morning oatmeal with keeping her off cholesterol medication.

She has outlived her husband and her siblings, and is surrounded with accomplished children, grandchildren and great-grandchildren who dote on her. Good thing, because she said her retirement money ran dry long ago.

"I never expected to live so long," Horowitz said.

Perls and his co-author, biostatistician Paola Sebastiani of the Boston University School of Public Health, agreed that long-term retirement planning might be one area where people will want to use their research.

Using the 150 markers, Sebastiani created a computer model able to predict the likelihood of living past 100 with 77 percent accuracy.

She said the model would be available to the public online in a week or two, meaning that once commercial longevity tests hit the market, people can quickly calculate their odds of living past 100.

Perls said he expects several companies to offer such genetic tests.

Will life insurance companies and financial planners want to put the information to work? University of Miami bioethicist Ken Goodman cautioned that science and society may not be ready.

"This is exciting science, but don't cancel your insurance policy yet," Goodman said. "Gene-gene interactions and gene-environment interactions are incredibly complex."

About 15 percent of people appear to have one of the beneficial genetic profiles, based on the control group. But those genes are no guarantee, Perls said. They appear to put people's odds of living into a second century at between 65 percent and 98 percent.

"If they're not hit by a bus, if they're not in a war, if they haven't had some other accident happen, maybe they get to fulfill that," Perls said.

Exactly what the 150 markers do is unclear. Some reside within known genes, but many do not. Some may play the role of genetic editors, affecting how and when other genes are put to work. Sorting it all out will require further study, the authors said.

Meanwhile, if people really want a gauge of how long they should expect to live, they should look at their family tree, Perls said. Horowitz's mother lived past 90, as did one of her grandmothers.

"It's very important to look at various diseases and what people are dying of, so that you can get an idea of what risk factors are not good for you," he said.

Horowitz plans to keep going for years to come. She does her daily crosswords and pays close attention to politics, often writing letters to the editor denouncing war and greed. Her advice to those who would live into a second century? Listen to music. Enjoy your friends and family. Be generous.

"Help people when you can, because the joy is twofold. You get joy from giving, and they get joy from getting," she said.