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November 12, 2012

Significant relationship between mortality and telomere length discovered

Eurekalert - A team of researchers at Kaiser Permanente and the University of California, San Francisco (UCSF) has identified a significant relationship between mortality and the length of telomeres, the stretches of DNA that protect the ends of chromosomes, according to a presentation on Nov. 8 at the American Society of Human Genetics 2012 meeting in San Francisco.

- individuals whose telomeres were in the shortest 10 percent were about 23 percent more likely to die in the three years following measurement of their telomeres, when compared with individuals whose telomeres were longer

While a reduction in telomere length is regarded as a biomarker of aging, scientists have not yet determined whether it plays a direct causal role in aging-related health changes and mortality or is just a sign of aging.

In their prospective study of 100,000 multi-ethnic individuals whose average age was 63 years, the researchers determined that an association between telomere length and mortality existed and persisted even after the data were adjusted for such demographic and behavioral factors as education, smoking and alcohol consumption, said Catherine Schaefer, Ph.D., director of the Kaiser Permanente (KP) Research Program on Genes, Environment and Health (RPGEH).

Science News - The 10 percent of people with the shortest telomeres had a more than 20 percent higher risk of dying than people with longer telomeres, Catherine Schaefer, an epidemiologist who directs the Kaiser Permanente Research Program on Genes, Environment and Health, reported November 8 at the annual meeting of the American Society of Human Genetics. “It seems as though once your telomeres get critically short, your risk of dying goes up,” she said. The increased death risk is about the same as for people who drink 20 to 30 alcoholic beverages per week or smoke for 20 to 30 years. “It’s a modest increase, but it’s not nothing.”


Telomeres do get shorter with age, the study confirms, but men older than 75 and women over age 80 tended to have longer telomeres than their slightly younger counterparts. That result does not mean that telomeres start to grow in length once people reach a certain age, Schaefer said. Rather, the finding probably means that people with shorter telomeres died before they reached those ripe old ages and the survivors are those that carry longer telomeres.

African-Americans tended to have longer telomeres than European-Americans, Latinos or Asians, the researchers found. The reason for that difference is not clear. As expected, people who smoked or drank heavily were more likely to have shorter telomeres, and higher levels of education were associated with longer telomeres. Other studies have linked exercise with longer telomeres, but Schaefer and her colleagues found no such association.

One of the study’s findings is rather puzzling, said Dan Eisenberg, an anthropologist at the University of Washington in Seattle who studies telomeres’ link to health, but who was not involved in the Kaiser Permanente study. Higher body mass index, or BMI, was associated with longer telomeres. The discovery is counterintuitive, Eisenberg said, because higher BMIs —those associated with being overweight or obese — are linked to a variety of health problems including diabetes and heart disease. Eisenberg said he would have expected telomeres in people with higher BMIs to be shorter.


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