Further update, 25 July 2011: Last Friday Science officially retracted the paper on which this article is based following quality control checks by an independent laboratory. According to a retraction notice written by the study authors: 鈥淲e feel the main scientific findings remain supported by the available data鈥� However, the specific details of the new analysis change substantially from those originally published online.鈥�
Update, 8 July 2010: Since this article was written, some researchers have raised concerns over an error in the way the 鈥済enes for long life鈥� were identified that could cause false positive results. A DNA chip which was used to sequence the genomes in the study as having a tendency to get some details wrong, and is casting doubt on the study鈥檚 results. We will continue to monitor the situation as it unfolds.
Original article, 7 July 2010
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IF A genome test could predict your odds of living to 100, would you want to know? That鈥檚 the question posed by the possibility of a longevity scan based on genetic markers uncovered in people who lived to be 100 years old.
As part of an ongoing study of , and of Boston University in Massachusetts compared the genomes of 801 centenarians of white European ancestry, born between 1890 and 1910, with those of 926 people who died before reaching 100.
The team identified 150 single nucleotide differences 鈥� variations in a single letter in our genetic code 鈥� that are far more likely to be found in the genomes of centenarians than in people who die before the age of 100. Many of these markers are, not surprisingly, related to the body鈥檚 ability to stave off age-related diseases such as heart disease and dementia.
Next, the team created a genetic model which they applied to a new group of centenarians and controls. By analysing their genomes, the model correctly distinguished the centenarians from the rest 77 per cent of the time (Science, ).
The study鈥檚 main conclusion is confirmation that genetics plays an important role in extreme longevity. Does it also suggest that people are a genetic test away from knowing how long they are likely to live?
Probably not, but that doesn鈥檛 mean people won鈥檛 get themselves tested, Perls says. The consumer genome scans offered by firms such as 23andMe cover the gene markers that the team identified, and these or other companies could recreate the team鈥檚 predictive model. Anticipating this possibility, the team is launching a website where people can submit their raw genetic data to obtain a longevity prediction 鈥� along with a list of caveats.
鈥淎re we a genetic test away from knowing our likely lifespan? Probably not, but some will still get tested鈥�
For starters, the findings have only been tested in people of white European ancestry and there is no guarantee they will apply to other ethnic backgrounds. Nor is there a rigid link between genetics and longevity, Sebastiani notes: some people with these genetic markers clearly won鈥檛 live to 100.
The results still need to be independently corroborated, says K谩ri Stef谩nsson, CEO of , a genetics company based in Reykjavik, Iceland. He says none of the genetic markers the Boston team identified is correlated with extreme longevity among the Icelanders his firm studies, and he has no plans to offer this particular longevity test to deCODE鈥檚 customers.
Another issue is whether a potential consumer gene scan for longevity could affect health, lifestyle and financial decisions, says Perls. 鈥淚t鈥檚 going to be like getting your palm read,鈥� says , a geneticist at Boston University, who was not part of the study. 鈥淚t鈥檚 not like risk of cancer.鈥� He thinks people may therefore be less anxious over the results of a genetic test for longevity and are unlikely to read too much into them.
Longevity and other attributes are associated with a multitude of genetic and environmental factors. The trick will be communicating such subtleties to users of consumer genetic tests, says Green. He is embarking on a study to find out how people interpret and use information from their genomes.
