Genes and Longevity

Boston University scientists claim to have identified a small set of genetic variants that predicts extreme longevity.

The scientists, Paola Sebastiani and Thomas Perls, examined the DNA of 1,055 centenarians living in New England. They isolated 150 gene variants that were common in this population. They subsequently examined a separate sample of centenarians and found that 77% of them had many of the same genetic variants.

The centenarians in the original cohort had as many disease-associated gene variants as shorter-lived people, so the scientists reasoned that the genes they identified must protect against disease.

This conclusion is at odds with current thinking about extreme longevity which is predicated on the assumption that long life is caused by the absence of disease-causing gene variants, rather than the presence of protective genes.

To find the protective genes, the scientists implemented a genome-wide association study, a technique that has so far failed to meet expectations that it would unlock genetic secrets behind common conditions like diabetes and Alzheimer’s disease.

Some scientists questioned the findings of the BU group. Kari Stefansson, a geneticist who works for Decode Gentics told the New York Times for example, that he was “amazed at how many loci of genome-wide significance have been found in a modest sample size.”

Stefansson’s company has also studied extreme longevity. Apparently, none of the BU group’s 150 genetic variants showed up in the population studied by Decode Genetics.

There are roughly 80,000 centenarians in the US right now. Roughly 15 % of the general population has some or many of the 150 genetic variants found in the BU study. Most of them fail to reach a ripe old age because of accidents or an unhealthy lifestyle.

Their report appears in Thursday’s issue of Science.

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