Medicine

Can measuring telomeres help predict your life span?

By Lisa M. Krieger / San Jose (Calif.) Mercury News

The moment will come, we know, when we’re whisked off life’s stage.

But when? It’s a mystery that has haunted humans since the dawn of civilization. If it’s soon, we can cancel that dental appointment, quit the job and take a dream vacation. If not, plan for decades of decrepitude.

For me, a clue — perhaps — arrived in my email from a Menlo Park, California, company, Telomere Diagnostics. Its test measures the length of a protective cap, called a telomere, at the end of each strand of DNA, the genetic blueprint of life.

My telomeres are shrinking right now. So are yours. Every time a cell divides, its telomeres shorten until they reach a critical length, and the cell dies. Their shrinking serves as a clock that counts off a cell’s life span. They tell us: Time’s running out.

These tiny telomeres are so important to human biology that their discovery earned three American scientists the 2009 Nobel Prize.

So I leapt at the chance to have my telomeres measured — and get paid $50 per test — in Telomere Diagnostics’ yearlong study to identify normal telomere lengths and rates of change.

A telomere test is not yet — and will likely never be — life’s crystal ball. There are other theories to explain aging, such as damaged cell membranes and mutated DNA.

But a fast-growing body of research is finding that telomere length in leukocytes, the white blood cells of the immune system, reliably predicts age-related disease — and can be affected by genetics, chronic stress and health behaviors, such as exercise and diet.

Since then, several testing companies have been founded by respected scientists, such as Nobel laureate Elizabeth Blackburn of UC San Francisco and George Church, director of Harvard University’s Molecular Technology Group.

They’re part of the flourishing fields of retail genomics and personalized medicine, drawing on tools built for the Human Genome Project, where companies such as Mountain View, California-based 23andMe offer a tour of your genes. The proliferation of these “lab developed tests,” with companies marketing complex automated assays originally intended only for research purposes, is a growing concern among federal regulators.

The promise, though, is irresistible: For the first time in humanity’s long search for immortality, it’s possible to see how our cells are holding up against the ravages of time. Telomere science is inching us closer toward Weirdsville, where a simple blood test, not gray hair and creaky joints, measures aging.

“Telomere length is a biomarker of overall health status,” according to my research consent form, “and thought to reflect physiological age. … It is an ‘integrator’ of a broad range of current and lifelong factors that impact health, including genetics, diet, fitness, toxins and chronic stress.”

So far, so good.

As a working journalist in my 50s, with a lifetime of deadline pressures, lost sleep, child-rearing and freeway traffic, I feared that my chromosomal caps might be as paltry as the ends of old shoelaces.

But I also swim, jog, have strong friendships and maintain my high school weight. Surely, I hoped, my caps are thriving under all that discipline?

Information is power, I reasoned. If the news was gloomy, I’d force myself to learn meditation. Eat more vegetables. And buy that vacation plane ticket.

Three times over the next year, I drove to research sites and donated 10 teaspoons of blood, spit into a saliva collector, stood on a scale and answered questions about diet, exercise and stress. The company responded with newsletters about healthy living, such as how to help prevent breast cancer, prostate cancer and lung disease. (It did not respond to interview requests for this article.)

“It is worth doing. It does tell us something. It is the best measure we have” of cellular aging, said researcher of aging and Genescient CEO Bryant Villeponteau. But testing still belongs in a research setting, he said, not used as a personal diagnostic tool.

As more people take them, he said, “I think the tests will get better, with more potential to learn something.”

Finally, the day came. My results arrived in a password-protected email.

This is when other experts, such as Hank Greely, director of Stanford University’s Center for Law and the Biosciences, might hit the “delete” button.

“They are just one more unapproved test out there that hasn’t presented its evidence to an unbiased agency,” such as the U.S. Food and Drug Administration, said Greely, who specializes in the ethical, legal and social implications of biomedical technologies. “All we have is their ‘say-so’ that the test is good and — with all due respect to researchers whom I like and respect — that is not enough.”

He doesn’t object to companies providing data. What’s wrong, he said, is claiming that the data relates to a person’s health or longevity.

The biggest flaw with telomere testing is that the general trends we’ve learned from large research studies — “long is good, short is bad” — can’t be accurately applied to a single person, agreed Greely and scientist Judy Campisi of the Buck Institute of Aging, who has gained international recognition for her insights into the cellular basis of aging.

I remember Clara Cowell, the lively English woman who quit smoking at age 102; her family worried about house fires. And marathoner Jim Fixx, who died of a massive heart attack at age 52.

“There is a huge variability among people,” said Campisi, also a senior scientist at Lawrence Berkeley National Laboratory. Here’s another problem: The technology behind the tests is imperfect, yielding unreliable results, said Villeponteau.

But Villeponteau, author of “Decoding Longevity: Ending Aging as We Know It,” compares telomere testing to cholesterol tests: It “doesn’t tell you you’re going to have a heart attack. It doesn’t tell you that you’ll die at a certain age. But it is an important indicator of a common cause of death.”

I’m convinced. This email will be intriguing, but holds no more predictive power than the Gap sales promotion next to it.

Yet when I click open the file and a graph pops up on my screen, I catch my breath.

My telomeres scored well above average in the first test — in the 66th percentile compared with other participants of my age. They’re a hefty 2,520 nucleotides long. Hooray!

But — Help! — they inexplicably sag in the second test. Within a mere six months, they’ve fallen to only 2,400 nucleotides long, a decline that drops me to the 56th percentile for people my age. At this rate of shortening, I’ll predecease my iPhone.

The third test is even more disappointing: “NA.” There wasn’t enough usable data, according to the company, probably because the sample degraded during shipping.

Now that I have all this information, what sense do I make of it?

Maybe it means I have many happy years left, since both scores are above average. Or maybe it means that something catastrophic has happened, and I’ve already started a steep downhill slide.

Most likely, for me, it means nothing at all. But I hold hope that science is closing in on a deeper understanding of physical decay that may yet — someday — help us understand and lengthen the span of our years.

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