Published: May 18, 2011
(Page 2 of 2)
Telomeres are stretches of DNA linked to certain proteins that are at the ends of chromosomes. They are often likened to the caps at the end of shoelaces. Each time a cell divides, the telomeres get shorter. Eventually, the telomeres get so short that the cell can no longer divide. It enters a state of senescence or dies.
Telomeres are stretches of DNA linked to certain proteins that are at the ends of chromosomes. They are often likened to the caps at the end of shoelaces. Each time a cell divides, the telomeres get shorter. Eventually, the telomeres get so short that the cell can no longer divide. It enters a state of senescence or dies.
Life Length
María Blasco is a co-founder of Life Length, a company in Spain that sells a test for 500 euros ($712) that says that it can tell people their biological age.
, using blood samples from 143 elderly people collected in the 1980s, found that those with shorter telomeres were almost twice as likely to die in the ensuing years as those with longer ones.
Another study, published in The Journal of the American Medical Association last July, followed 787 people in Italy, all initially free of cancer. Those with the shortest telomeres had three times the risk of developing cancers in the next 10 years as those with the longest telomeres.
Still, not all studies have found such strong correlations. In any case, correlations do not prove that the shorter telomeres are causing the problems, although experts say some animal and cell studies do suggest causality.
Some say that the telomere test might not tell people much that cannot be learned in other ways.
“You can pretty much look at people and determine their biological age,” said Michael West, who founded Geron, the biotechnology company that sponsored and conducted some important research on telomeres. He now runs BioTime, another biotechnology company.
It is also unclear what to do about short telomeres. At the moment, there is no drug that can lengthen telomeres, though researchers are working on drugs and stem cell therapies.
There is some evidence, however, that stress is associated with shorter telomeres and that stress relief, exercise or certain nutrients such as omega-3 fatty acids might at least slow the decline in telomere length. But healthy lifestyles are already recommended for people without having to know their telomere length.
There are also disputes about how to measure telomeres. Life Length says its technique, while more expensive, can detect not only average telomere length but the shortest telomeres in cells. The shortest telomeres cause the health problems, said Dr. Shay, the adviser to Life Length.
Telome Health and SpectraCell use a DNA amplification technique called polymerase chain reaction, or P.C.R., which is cheaper but provides only an average length. And there are some questions about the accuracy.
Dr. Harley of Telome said the P.C.R. test was more relevant because virtually all the studies correlating telomere length with disease had used that test.
For those wanting to know how long they might live, there are already some indexes that are used by geriatricians to estimate the chances of a patient dying in anywhere from six months to nine years. A patient with a short expected lifespan, for instance, might no longer need to undergo annual screening for cancer.
These estimates rely on factors such as person’s age, gender, smoking history, whether they have certain diseases and whether they can perform certain functions, like walking several blocks, pushing an armchair or managing their finances.
Dr. Sei Lee, an assistant professor at the University of California, San Francisco who developed a test that estimates the probability of dying within four years, said he was not sure how much telomere length testing would add. “The chance of any single factor being a great predictor is probably low,” he said.
Still, not all studies have found such strong correlations. In any case, correlations do not prove that the shorter telomeres are causing the problems, although experts say some animal and cell studies do suggest causality.
Some say that the telomere test might not tell people much that cannot be learned in other ways.
“You can pretty much look at people and determine their biological age,” said Michael West, who founded Geron, the biotechnology company that sponsored and conducted some important research on telomeres. He now runs BioTime, another biotechnology company.
It is also unclear what to do about short telomeres. At the moment, there is no drug that can lengthen telomeres, though researchers are working on drugs and stem cell therapies.
There is some evidence, however, that stress is associated with shorter telomeres and that stress relief, exercise or certain nutrients such as omega-3 fatty acids might at least slow the decline in telomere length. But healthy lifestyles are already recommended for people without having to know their telomere length.
There are also disputes about how to measure telomeres. Life Length says its technique, while more expensive, can detect not only average telomere length but the shortest telomeres in cells. The shortest telomeres cause the health problems, said Dr. Shay, the adviser to Life Length.
Telome Health and SpectraCell use a DNA amplification technique called polymerase chain reaction, or P.C.R., which is cheaper but provides only an average length. And there are some questions about the accuracy.
Dr. Harley of Telome said the P.C.R. test was more relevant because virtually all the studies correlating telomere length with disease had used that test.
For those wanting to know how long they might live, there are already some indexes that are used by geriatricians to estimate the chances of a patient dying in anywhere from six months to nine years. A patient with a short expected lifespan, for instance, might no longer need to undergo annual screening for cancer.
These estimates rely on factors such as person’s age, gender, smoking history, whether they have certain diseases and whether they can perform certain functions, like walking several blocks, pushing an armchair or managing their finances.
Dr. Sei Lee, an assistant professor at the University of California, San Francisco who developed a test that estimates the probability of dying within four years, said he was not sure how much telomere length testing would add. “The chance of any single factor being a great predictor is probably low,” he said.
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