Newly published whole genome analysis of two supercentenarians has shed light on the genetic factors that allow some humans to live to extreme old age.

The genomes of a man and a woman both aged older than 114 years were sequenced and analysed by researchers in the US.  Supercentenarians are those humans who have lived for more than 110 years and occur at a rate of one person per five million.

With regard to novel variants, functional variants, and variants that predispose to common age-related diseases and common cancers, the genomes were similar to those already published.

This suggests that other mechanisms were at work which allowed the pair to live to such an old age.

Indeed, the male subject exhibited 37 genetic mutations which have been linked with an increased risk of colon cancer. Earlier in his life, he had suffered from obstructing colon cancer that had not metastasized and was cured using surgery.

The woman was found to have a number of genetic variations linked with Alzheimer's, cancer and heart disease, although mild cognitive impairment or congenital heart disease did not appear until the age of 108.

Dr. Thomas Perls, director of the New England Centenarian Study and senior author of the article, said: "The difference may be that the centenarians likely have longevity-associated variants that cancel out the disease genes.

"That effect may extend to the point that the diseases don't occur – or, if they do, are much less pathogenic or markedly delayed towards the end of life, in these individuals who are practically living to the limit of the human lifespan."

Over 50 putative longevity-associated variants in genes that determine two forms of progeria and those linked with cardiovascular disease and Alzheimer's disease were also discovered, which the team believe requires further research.

The research was carried out by Boston University Schools of Public Health and Medicine and Boston Medical Center, the University of Florida, Gainesville, and The Scripps Research Institute. The full study is available in the open-access journal Frontiers in Genetics.

Analysis conducted by researchers from 15 nations recorded over 600 supercentenarians, with almost 20 living beyond 115, as of June 2010. Ninety per cent of those living over 115 years were women, PhysOrg reported.