July 2, 2010

Gene Sequence Predicts Who Lives To 100

Boston University researchers have discovered a genetic sequence that predicts with more accuracy than ever before whether a person will live to the age of 100 -- even if they have other genes associated with disease.

The scientists studied over 1,055 centenarians to develop a system of genetic analysis that predicts with 77-percent accuracy whether a person has a strong chance of "exceptional longevity". 

The predictions involve identifying the presence of 150 genetic variants known as single nucleotide polymorphisms (SNPs), which researchers have found to be common among those who live significantly longer than the average population.

"There is a very strong familial component to exceptional longevity," said the study's co-leader, Thomas Perls, in an interview with the AFP news agency.

"And that, in conjunction with some other work, has always made us believe that genetics is playing a very important role" said Perls, a biostatistics professor at Boston University School of Public Health.

"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."

The researchers used computer modeling to track the presence of the multiple genetic variants in study participants and members of control groups, and singled out the most predictive SNPs.

The team identified 19 different "genetic signatures" of exceptional longevity found in 90 percent of the study participants, with the different signatures correlating with differences in the prevalence and the age-of-onset of age-related diseases.

Of the study participants aged 110 or older, 45 percent had the genetic signature "with the highest proportion of longevity-associated genetic variants."

Identifying these variants "may help identify key subgroups of healthy aging," the researchers said.

Perls said the genetic signatures represent "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."

The fact that there seemed to be little difference between the subjects and the control group in disease-associated variants was a critical finding of the study, the researchers said.

This suggests that the presence of the genetic variants linked with longevity was more important than the absence of disease-associated genes. 

If so, then "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 researchers said.

Centenarians are valuable research subjects because they provide vital insight into age-related diseases such as cancer, cardiovascular disease and dementia.

"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," said Perls.

Despite the study's promising results, the scientists emphasize 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," they said.

The findings were published online Thursday in the journal Science.


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