The Geriatric Genotype?

Posted by Brendan Parent on July 7th, 2010

The combination of 150 genetic mutation points appears to indicate a predisposition to extreme longevity (100 years+), according to a study by Sebastiani et al reported in the July 1 issue of Science. The study is attracting a fair amount of news coverage. While some headlines are jumping the gun, claiming "Genes are the Key to Long Healthy Living" and "Longevity Genes Found; Predict Chances of Reaching 100," many are recognizing the limited predictive and social value of the test.

The researchers identified the genetic variations by analyzing 1,055 centenarian genomes and then applying their findings to an independent set of centenarian genomes; they found a 77% correlation between the mutations and extreme longevity. As Matthew Yglesias of Think Progress points out, that leaves plenty of room for false positives. According to his math, the genetic variations in question actually confer only a 37% chance of living to 100.

Newsweek raises additional concerns about the study's accuracy in an article titled "Scientists Discover the Fountain of Youth! Or Not." Geneticists David Altshuler (Broad Institute) and David Goldstein (Duke) point out that potential "false apparent relationships" might be drawn when data used in the control group is collected outside of the lab in which the other set of data was compiled.

Beyond questions about methodology are the social hazards of information about genetic predisposition to longevity. Tucked beneath the bandwagon headline "Scientists Discover Keys to Long Life," Wall Street Journal's Robert Hotz insightfully posits: "People with genes for extreme longevity could face a series of difficult decisions about their careers, retirement savings, insurance coverage, medical treatments and marriages in old age." These considerations are echoed in an NPR interview, in which the researchers themselves admit to not having taken the test, saying that it is "not quite ready for primetime" and that the information may lead to unhealthy or dangerous decisions.

And then there's the point that we already know a lot about how to live longer. Brandon Keim of Wired writes:

Other studies suggest that whether or not someone lives to their 80s is mostly a result of common-sense lifestyle choices: moderate drinking, no smoking, plenty of exercise, a vegetable-centric diet and low stress.

Regardless of how strong genetics' role in longevity turns out to be, emphasizing it over common-sense empirical health maintenance techniques is unwise. The last sentence of the Science article acknowledges this:

This prediction is not perfect… its limitations confirm that environmental factors (e.g., lifestyle) also contribute in important ways to the ability of humans to survive to very old ages.

Lifestyle choices are indeed important to health. But another factor in healthy aging is painfully absent in nearly all the recent discussion. Social determinants largely set the conditions of birth, growth, diet and health care, and the uneven distribution of resources preempts individual choices about working out and eating leafy greens.

The World Health Organization's Commission on Social Determinants of Health advises that health and life expectancy be improved by focusing on policies that promote affordable housing, reasonable minimum wage, quality education, and health care. For much of the world's population, access to these kinds of basic resources easily trumps the contributions either of lifestyle or genes.

Previously on Biopolitical Times:

Genes of the Week

Posted in Sequencing & Genomics


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