Longevity Genes Cannot Explain Why Centenarians Live So Long

One study of more than 1000 centenarians led by Boston University researchers including Thomas Perls and Paola Sebastiani and published in the prestigious science journal Science identified 150 gene variants that are associated with extreme longevity defined as a lifespan of over 100 years.

Most supercentenarians had all the longevity markers while centenarians had various combinations of the genetic variants, which can be categorized in 19 genetic profiles.

Centenarians were not free of genetic variants that are associated with diseases.  But the fact that they are not affected by the diseases is probably due at least in part to the longevity SNPs which in reality cancel the negative effect of the disease gene variants.

The study involved 1,055 centenarians and 1,267 younger people.  An initial study only identified 33 SNPs, but Perls, Sebastiani and colleagues believe there should be more and their work eventually led to the discovery of 150 SNPs linked with extreme longevity .

A statistical model based on the 150 SNP variants was reportedly able to predict who was a centenarian 77 percent of the time.  

However, this genetic model did not mean to predict someone in the general population may or may not live over 100 years, Sebastiani said, even though 77 percent is a high accuracy for a genetic model.

Nicholas Schork, a statistical geneticist at the Scripps Translational Science Institute and the Scripps Research Institute was cited as saying that these gene variants do not mean to be used to predict a person's longevity in a general population because they are just markers. 

That is, essentially whether these gene variants play any major role in the retarded aging process remains unknown even though some genes have been found associated with certain diseases like Alzheimer's disease, chromosome stability and insulin among others.

The scientists still do not know why the model based on these newly located genetic variants could not accurately identify all the centenarians. This led them to believe that there may be some other rare genetic variants or lifestyle, which largely remains unknown, or a combination of both genetics and lifestyle parameters responsible for their longevity.

According to a report by sciencenews.org, only one in 6000 people lives long enough to be a centenarian and one in 7 million lives to be a supercentenarian, who enjoys a lifespan of 110 or more years.

ScienceNews cited Perls as saying that about 15 percent of the general population have the genetic foundation to help them potentially to live 100 years and whether or not they can live so long depends on environmental factors.

Overall, genetics only accounts for 20 to 30 percent of a person's chances of living beyond 85 years, according to the ScienceNews report.  And environmental factors such as diet and healthy lifestyle may play a major role in a person's longevity.

By David Liu