It may be possible to predict the lifespan of patients being treated for heart disease by taking a look at the lengths of strands of DNA found on the ends of special chromosomes called telomeres, according to a study by the Intermountain Heart Institute in Utah, which was presented Saturday at the American College of Cardiology’s Annual Scientific Session in San Francisco. It’s a pretty simple rule of thumb: The longer the telomeres, the longer the patient could be expected to survive.
Just as our hair gets more brittle and likely to fray with age, chromosomes also get shorter with age, explained John Carlquist, director of the institute’s genetics lab. “Once they become too short, they no longer function properly, signaling the end of life for the cell,” he said. “And when cells reach this stage, the patient’s risk for age-associated diseases increases dramatically.”
Non-medical folks can imagine the telomeres as functioning a bit like the tip on your shoelaces. As long as the tip is long, strong, and working, the chromosome won’t fray and come apart. However, once the tip is frayed, the chromosome starts to unravel, and serious diseases of aging like cancer or heart disease can be the result.
A previous study, conducted on zebra finches, had demonstrated the long telomeres in young, healthy animals could be used to predict lifespan. Individual zebra finches have telomeres that vary a great deal in length even at the same age. The birds with the longest strands ultimately outlived the birds with shorter strands — and sometimes by quite a lot. Birds destined to die early passed away within their first year of life, while the longest lived finches survived to be almost 9 years old.
What’s new about the Utah study is that, instead of looking at relatively young organisms, the doctors examined DNA strands from older patients who were already suffering from disease. Even though all of the patients had heart disease, they still showed individual variation in the length of their telomeres, and those people who had the longer telomeres lived the longest after receiving treatment.
If I was the poor finch destined to die 8 or 9 times earlier than my buddies, I’m not sure I would want to know. However, the Utah cardiologists believe that if they can predict who will respond best, they can ultimately plan better and more individual treatments for everyone.
Would you want your doctor to be able to easily predict your lifespan?
[micrograph of diseased heart tissue courtesy Wikipedia Commons]