Saturday, 3 July 2010

Genes behind long life found


“Genes that mean you will live to 100” have been discovered by scientists, said The Daily Telegraph.

The news is based on a study by US scientists who have built a genetic model that can predict exceptional longevity, defined as survival well beyond the average human lifespan, with 77% accuracy.

This is an interesting study that built and tested a genetic model for exceptional longevity in over 1,000 centenarians and 1,200 control subjects. It indicates that genetic factors play a critical and complex role in living an exceptionally long time.

However, as the scientists note, their model is not perfect and further research on the variations of the human genome are needed to improve on this. Whether this research is likely to be turned into a commercially available test is unclear, as is whether this test would be helpful for the individual. Our environment and lifestyle also clearly play a role in longevity, and so it seems sensible to increase our chances of reaching a healthy old age through controlling these modifiable factors where possible, regardless of our genes.

What were the basic results?

In the first part of their study, the researchers identified 70 SNPs (Single Nucleotide Polymorphisms - a change of a nucleotide at a single base-pair location on DNA.) that were significantly more common in centenarians than controls.

The researchers developed a model for predicting extreme longevity based on 150 SNPs. They found that their model correctly identified exceptional longevity in 77% of their replication set of centenarians. The model also correctly identified 77% of those who did not have exceptional longevity (controls).

Further computer analysis revealed that 90% of the centenarians could be grouped into 19 ‘clusters’ of those who had similar genetic make-up, which they termed ‘genetic signatures’. These clusters had differences in the prevalence and age of onset of age-associated disease such as dementia, high blood pressure and cardiovascular disease.

The researchers also says that while large numbers of longevity-associated variants (LAVs) within the genes appear to be necessary for extreme survival, they did not observe a difference between centenarians and controls in the numbers of many known disease-associated genetic variants. They say that this suggests that extreme longevity may be the result of an ‘enrichment’ of longevity genes that counter the effects of genetic variations that predispose towards disease.

How did the researchers interpret the results?

The researchers say they have identified the genetic data to predict extreme longevity without knowledge of other risk factors. They acknowledge that the prediction is not perfect, and its limitations confirm that environmental factors also contribute to the ability of humans to survive to very old age.
In a separate interview reported by the newspapers, one of the researchers predicted that this information, freely available in the public domain, could be used by biotechnology companies to develop a commercial test for extreme longevity, although he added, society was probably not ready for this.

Links to the headlines

Scientists discover what makes us live longer. The Independent, July 2 2010
Genes predict living beyond 100. BBC News, July 2 2010

Links to the science

Sebastiani P, Solovieff N, Puca A et al. Genetic Signatures of Exceptional Longevity in Humans. Science, [published online] July 2010

No comments: