Can a simple blood test tell you how your lifestyle is affecting your lifespan? Geneticists seem to think so, and have recently begun founding start-up companies aiming to do exactly that. By measuring the length of one’s telomeres, the dense “caps” on the ends of chromosomes, researchers believe they can estimate how healthy you are relative to people your age. Replication of DNA in humans, like in all eukaryotes, progresses in only one direction on the strand of DNA, and this makes replication at the chromosome’s ends difficult. The result is a progressive loss of short DNA sequences with each replication cycle, shortening the telomeres. This regular loss of DNA acts as a biological clock for eukaryotes, similar to the carbon isotopes measured in carbon dating. Researchers believe that by comparing this measured “telomere age” with a patient’s actual age, they can get a general idea of his or her overall health.
Although telomere lengths, like height and weight, vary throughout the population, distinct correlations exist between groups with similar lifestyles. People who exercise regularly tend to have longer telomeres, while factors like cardiovascular disease, stress, and obesity have been shown to correlate with shorter telomeres. Calvin B. Harley, a genetics researcher and founder of the telomere research company Telome Health, goes as far as to say telomere length is “probably the best single measure of our integrated genetics, previous lifestyles, and environmental exposures.” But, exactly how much our telomere length can tell us is still up for debate; some researchers believe more extensive trials need to be done before this type of measurement has any credibility, while others believe that preserving our telomeres can even prevent aging (try googling “telomerase” and see how many people think this single enzyme can be our aging cure!).
Written by: Walter Palmer