Got genes for longevity?

Scientists discovered genes associated with old age. Will there be a test for longevity?
Written by Boonsri Dickinson, Contributing Editor

The chance that you will ever reach 100-years-old is pretty good considering, 1 in 6,000 people in the industrial world make it to their triple digit birthday.

But your odds of becoming a centenarian might be better if you have the genes for it, according to Boston University scientists.

As many as 15 percent of Americans have the genes to be a centenarian, but unfortunate events like getting hit by a bus and environmental factors like smoking and being obese decrease the odds of actually getting there.

The researchers claim with startling accuracy, that they can predict if someone is biologically destined to live a long life. In general, centenarians are an ideal bunch to study: Not only do they represent healthy models of aging, they also don't usually have a disability until 93.

For this study, the researchers studied 1,055 centenarians and 1267 controls (spouses of centenarian offspring or children of parents who died at the mean age of 73 years) using a common technique called genome-wide association.

Paola Sebastiani, a biostatistician at the Boston University School of Public Health, wrote in Science:

"Using these data, we built a genetic modelthat includes 150 single-nucleotide polymorphisms (SNPs) andfound that it could predict EL with 77% accuracy in an independentset of centenarians and controls."

Based on that, the researchers could predict with 77 percent accuracy if someone would live to 100 or longer. They found 150 gene variants associated with long life.

The samples were categorized into 19 genetic profiles. The finding doesn't suggest that the people have a lack of genes that predispose them to disease, but instead the genes offer an "enrichment of longevity-associated variance."

"The 'super centenarians' who live beyond 100, had three genetic signatures in common," reports The Washington Post. Some of the people had genes that delayed the onset of diseases such as cancer and dementia, while others did not. There's not a clear association, as many pathways are involved.

So you're probably wondering about the 23 percent of people who didn't have the genetic signature for healthy aging but still managed to get there. National Geographic suggests:

Maybe this minority "lived long simply because they had some tricks and avoided risk factors," Sebastiani said. "Perhaps they didn't smoke, didn't eat much red meat, or just lived healthier lives."

Kari Stefansson, an Icelandic geneticist, who has studied longevity in the Icelandic population says, "I am very surprised by this large number of loci coming out of this very small cohort of centenarians. I am also concerned that the controls were genotyped on different platforms. This usually leads to problems."

"When you look at the study, these results are never going to hold up. We haven't seen any of these associations," Stefansson adds, referencing the genetic studies done through his company, deCODE Genetics.

Other scientists see the longevity discovery in a different light. The New York Times reports:

“I think it’s a quite striking finding,” said Nir Barzilai, an expert on longevity at the Albert Einstein College of Medicine. It shows that only a limited number of favorable genes are required to attain great age, he said. Identifying these genes would provide protection against all the diseases of old age, a more powerful strategy than tackling each disease one by one.

“I feel there’s an elephant in the room and no one realizes it’s really important — this is the next step to make us all healthy,” Dr. Barzilai said.

The search for longevity isn't new, but still seems like an unattainable goal.

Even if you don't have these so-called longevity genes, the research could one day benefit you.

But not in the form of a longevity pill.

Scientists could develop new treatments and come up with ways of preventing age-related diseases to delay the onset of Alzheimer's for instance.

That's why in the future, it wouldn't be surprising to see longevity tests show up in consumer tests offered by companies like deCODEme and 23andMe.

For example, 23andMe already offers preliminary results for longevity. After seeing this Boston study, I was curious to know if I had any genes for longevity based on my 23andMe profile.

I logged onto my account and this is what I saw: According to one study, I have typical odds of reaching 95 or beyond. Another one said I have typical odds of reaching 100.

Ok, that's nice. But I'm not sure what to think of that.

These results are hardly conclusive. 23andMe warns that:

Preliminary Research includes results of studies that still need to be confirmed by the scientific community. It also includes topics where there may be contradictory evidence. The results of these studies are not conclusive.

Longevity runs in families — I know this from experience. When I looked at my genetic ancestry in a story for Discover magazine, I found that:

The report added some details about my place in haplogroup D: I belong to subgroup D4a. “Your maternal ancestor was probably from Siberia and northern China,” Joanna Mountain, senior director of research at 23andMe, explained. People in subgroup D4a have a gene for longevity, consistent with what I know about my grandmothers and great grandmothers, who all lived well into their nineties.

But I'm not going to count on my genes for a long life or hope that I age gracefully like my grandmas. That's why I eat well and exercise often, so I can lower my chances of developing common diseases later on in life.

Photo: edwardyanquen / flickr

This post was originally published on Smartplanet.com

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