Surprisingly, the researchers found that approximately 15 percent of control subjects also had the genetic signature associated with longevity. This suggests that many more people have the genetic potential to survive into old age than previously thought. "We know a lot about the human genome, but we also know that there is a lot that remains to be discovered," Sebastiani said. "Genetics is fundamental in EL, but it's not the only thing. So there may be other factors like environment or other lifestyles that may help people live longer and healthier lives," he added.
Importantly, there was no difference in the presence of known disease-associated gene variants between the longevity and control groups. The researchers conclude that EL may result from an enrichment of longevity-associated gene variants that may counteract the effects of having a disease-associated gene.
"I think this is a step towards making sense out of a lot of data—genetic data, environmental data, epidemiological data—to help us understand factors that contribute to long and healthy life," says Winifred Rossi, deputy director of the Division of Geriatrics and Clinical Gerontology at the National Institute on Aging, who wasn't involved in the study.
"We're starting to get to the point where it might be possible to use the information about these variants to predict someone's likelihood of achieving EL," says Matt Kaeberlein, professor of pathology at the University of Washington in Seattle, also not involved in the study. He added that the challenge was to next move beyond this correlative study to figure out how these gene variations may lead to functional changes that contribute to the molecular process of aging.
The authors caution that further study and replication of their results in different populations is needed to verify their model before it will be useful for individual genetic tests—or before longevity "cocktails" are created.
"My hope has always been with the study that we would learn much more about how to get lots of people to live to older age in good health and markedly delay their disability and age of onset of diseases…," Perls said. "I look at the complexity of this puzzle and feel very strongly that this will not lead to treatments that will get a lot of people to become centenarians, but rather will make a dent in the onset of age-related diseases like Alzheimer's, for example."