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If there were a medical test that could tell you whether you would live to be 100, would you take it? That's no longer a hypothetical question. Scientists from Boston University report they have a first version of such a test and they're hoping it will lead to a better understanding of the genetics of why some people live longer than others. NPR's Joe Palca has more.
JOE PALCA: Fifteen years ago, scientists in Boston began the New England Centenarian Study. The criteria for participating, you had to be at least 100 years old.
Dr. THOMAS PERLS (Geneticist, Boston University): The oldest subject in our study was 119.
PALCA: Thomas Perls is director of the study. Perls says whatever other factors are involved in living into your hundreds, genes must play a role. Longevity definitely runs in families, but which genes and how they worked was a mystery. So Perls teamed up with Boston University geneticist Paola Sebastiani.
Mr. PERLS: And left it up to Dr. Sebastiani to solve the genetic puzzle.
PALCA: OK. And so, Dr. Sebastiani, did you solve it?
(Soundbite of laughter)
Dr. PAOLA SEBASTIANI (Geneticist): I think we went step ahead. Maybe we haven't solved it completely.
PALCA: Sebastiani took samples from the centenarians and looked for differences between their DNA and the DNA of normal-aged people. As she reports in the journal�Science,�she was able develop a computer model that used 150 genetic markers, specific bits of DNA scattered around the 23 pairs of human chromosomes, to predict who would be able to join the centenarian club.
Dr. SEBASTIANI: And the accuracy of this model is 77 percent.
PALCA: The model also allowed Sebastiani to identify genetic signatures: gene patterns that were present in subgroups of centenarians with particular characteristics. For example, the subgroup who lived the longest was also the group most likely to have delayed onset of diseases that typically affect older people.
Dr. SEBASTIANI: For example, dementia, cardiovascular disease, hypertension.
PALCA: In other words, Sebastiani says not only did these people live long lives; they lived long, healthy lives.
So have you tested yourself for your genetic signature using these markers?
Dr. SEBASTIANI: Not yet.
PALCA: Neither has her colleague Thomas Perls.
Dr. PERLS: Actually the various authors of the paper feel that this really isn't quite ready for prime time.
PALCA: First, the test isn't 100 percent accurate. But second, what would you do with the information? OK. Maybe you'd do a better job of saving money if you knew you were going to live to 100. But Perls says consider the flip side.
If people knew they were unlikely to live to 100 they might stop watching their weight or exercising or start doing dangerous things like...
Dr. PERLS: Jumping out of an airplane and being a real risk taker, because I'm not going to live a long time, versus maybe I shouldn't be such a risk taker.
PALCA: Perls and Sebastiani agree that the real value of this study should be what it will tell scientists about the genetics of aging.
Dr. SEBASTIANI: At the moment this is a statistical analysis. And a lot of work has to be done to then understand what is the biology, what is the contribution of all these different genetic markers. So this is a first step.
PALCA: Geneticist Richard Myers of the Hudson Alpha Institute for Biotechnology in Birmingham, Alabama, agrees.
Dr. RICHARD MYERS (Hudson Alpha Institute of Biotechnology): This is sort of the first hint of regions of the genome that might be important for extreme longevity. And it's - you have a hint, and that's better than having nothing.
PALCA: But it does mean understanding the genetics of longevity will take a while, maybe even 100 years. If we live that long.
Joe Palca, NPR News, Washington.