Will you live to 100? Scientists say it's in your genes

Explorers the world over have long sought the fountain of youth, but now researchers claim they have hit upon something tangible: genetic sequences that can predict whether you'll live to the ripe age of 100.

A team of scientists from Boston University studied over 1,000 centenarians to develop a system of genetic analysis by which they can predict - with a 77-percent accuracy rate - whether someone has a strong chance of "exceptional longevity," according to findings published Thursday in the journal Science.

The predictions can by boiled down to the presence of 150 genetic variants, called single nucleotide polymorphisms (SNPs), which doctors and researchers found to be common among the elderly who live substantially longer than the average population.

"We have noticed in the study that there is a very strong familial component to exceptional longevity and that in conjunction with some other work has always made us believe that genetic is playing a very important role" in longevity, said Thomas Perls, a biostatistics professor at Boston University School of Public Health and co-leader of the study.

"Centenarians are indeed a model of aging well. We have noticed in previous work than centenarians are disability free at the average age of 93 so they very much compressed their disabilities toward the very end of their life."

Using computer modeling, the team tracked the presence of the multiple genetic variants in the study subjects and members of control groups to identify the most predictive SNPs.

The researchers also identified 19 different clusters, or "genetic signatures" of exceptional longevity, found in 90 percent of the subjects, with the different signatures correlating with differences in the prevalence and the age-of-onset of diseases such as dementia.

They noted that of the oldest subjects in the study - those age 110 or older - 45 percent of them had the genetic signature "with the highest proportion of longevity-associated genetic variants."

Pinpointing such variants, the authors said, "may help identify key subgroups of healthy aging."

Perls described the genetic signatures as "a new advance towards personalized genomics and predictive medicine, where this analytic method may prove to be generally useful in prevention and screening of numerous diseases, as well as the tailored uses of medications."

A key finding, the authors said, was that there appeared to be negligible difference between the subjects and the control group in disease-associated variants, suggesting that the presence of the genetic variants linked with longevity was of greater importance than absence of disease-associated traits.

Should the finding prove correct, "predicting disease risk using disease-associated variants may be inaccurate and potentially misleading, without more information about other genetic variants that could attenuate such risk" the authors said.

Centenarians are vital research subjects because they can provide doctors with key insight into age-related diseases such as cancer, heart disease, and dementia progress in the elderly.

"My hope has always been with the study that we would learn more about how to get lot of people to live to an older age in good health and markedly delay the disability and age of onset diseases toward the very end of their live," Perls said.

Despite the positive record of predicting longevity without knowledge of other risk factors, the authors stressed that "this prediction is not perfect."

"Its limitations confirm that environmental factors (e.g., lifestyle) also contribute in important ways to the ability of humans to survive to very old ages," the researchers wrote.

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