Reaching immortality is still in the realm of science fiction. But using clues from our genes, scientists are one step closer to understanding why some of us live to be centenarians while others don't.
Using a specific set of genetic markers, scientists predicted with 77-percent accuracy whether someone would live to a very old age.
The findings do not mean that lifestyle factors, such as healthy diet and exercise, are not important for long life. Indeed, 23 percent of the time the genetic markers didn't predict longevity. So those long-lifers without the centenarian genes might have practiced healthy habits that allowed them to lead a longer life. [Learn more facts about centenarians]
But they do suggest our genes play an important role when it comes to living well past the average lifespan. With more research, one day people might be able to determine whether they have the genetic potential to become a centenarian.
Additionally, learning more about how centenarians ward off diseases, including dementia, heart disease and cancer, well into their elder years, might help the rest of us delay disease.
"I'm very hopeful that understanding how and why centenarians are able to do that will lead to strategies and therapies, including screening and figuring out who could be helped by whatever therapies [there] are down the road," study researcher Tom Perls, of Boston University School of Medicine, said in a press briefing Wednesday about the study.
The results will be published this week in an early online edition of the journal Science.
The researchers compared the genomes of 1,055 centenarians (average age of 103) with those of non-centenarian controls.
They identified differences in the genetic code, known as genetic variants or markers, that were common in centenarians but not in the average population.
Using a computer model, they found 150 of these markers could predict 77 percent of the time whether a person lived into their late 90s and beyond.
Additionally, they saw 90 percent of the centenarians could be categorized into one of 19 groups based on which genetic variants they had. In other words, each group had a distinguishing "genetic signature" made up of certain genetic markers.
Differences in these genetic signatures may relate to differences in the way extreme longevity manifests itself. For instance, some genetic signatures were associated with extremely old age (living 110 years or more), while others were associated with a late onset of diseases such as dementia.
So can someone live to old age without these markers? Perhaps. About 30 of the centenarians had almost none of the longevity associated markers. In these cases, extreme old age might be influenced by other markers that have yet to be identified, or by the subject's lifestyle.
The researchers were also curious if centenarians had fewer markers that are known to be linked with diseases. However, in this respect, they found little difference between the centenarians and the control group.
This might mean that centenarians owe their exceptional lifespan not to less "bad genes," but to the presence of "good genes" that override the harmful ones.
This results suggests "that what makes people live very long lives is not a lack of genetic predisposition to diseases, but rather an arrangement of longevity associated variants that may be protective, it may even cancel the negative effect of disease-associated variants," said study researcher Paola Sebastiani, of Boston University School of Public Health, who also spoke at the briefing.
The researchers caution that before a genetic test for longevity is developed, scientists need to have a better understanding of what kind of effect the information could have on society, such as in the context of health care.
They hope the study spurs additional research into these genetic markers and how they might biologically contribute to longevity.
"I think that we're quite a ways away still in understanding what pathways governed by these genes are involved, and how the interaction of these genes, not just with themselves, but with environmental factors, are all playing a role in this longevity puzzle," Perls said.
The study was funded by grants from the National Institute of Aging (NIA) and the National Heart Lung and Blood Institute (NHLBI) of the National Institutes of Health (NIH).
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