Rare Gene Mutation Plays Role in Longevity

TUESDAY, March 4 (HealthDay News) -- A rare gene mutation that restricts a particular growth factor may be one of the keys to living to 100 and beyond, a new study suggests.

This mutation, which seems to decrease the activity of insulin-like growth factor (IGF-1), results in short stature but longer life. Exactly why this might lengthen someone's life isn't known, but the researchers say the finding might prove useful in developing anti-aging drugs.

"We found that people of a hundred years old have mutations in a gene that is related to the growth hormone pathway," said lead researcher Dr. Nir Barzilai, director of the Institute for Aging Research at the Albert Einstein College of Medicine in New York City. "We think this is important, because that's what now happens in nature. The pony lives longer than the horse, the small dog lives longer than a large dog. Apparently, it's true for humans also."

Interestingly, this particular mutation has been found mostly among women, he added.

It might be possible, given these findings, to develop drugs that can prevent aging and age-related disease, Barzilai noted. "There are drugs being developed to decrease growth hormone in patients with tumors, because sometimes cancer is dependent on growth hormones," he said. "Maybe we can adopt the strategy to slow aging."

The report was published in this week's online issue of the Proceedings of the National Academy of Sciences.

In the study, Barzilai's team looked for this mutation among a population of Ashkenazi Jews who were 100, and their offspring. They also matched these offspring with people who had no history of longevity in their family. The researchers found this particular mutation was more common among those who were centenarians and their offspring. The same research team reported in December 2006 that a particular gene variant that is linked to longevity is also associated with improved mental function in the elderly.

How long growth hormones need to be restricted to produce the slowing of aging isn't known. "Do you have it during early development in the womb, in puberty, or can you have it at any stage that you wish?" Barzilai asked.

Barzilai noted that growth hormone is a very popular anti-aging therapy. Growth hormone changes the tone of the skin and fat distribution, and increases muscle mass.

"However, this study and other studies suggest that, for the purpose of aging and longevity, growth hormone might do exactly the opposite," he said. "In the short run, growth hormones are going to have positive effects, but certainly in elderly people I would suggest, and this study supports the notion, that we will kill them sooner rather than later."

One expert thinks the findings are intriguing but inconclusive.

"This is an interesting study, which has to be replicated by other researchers using a different dataset, because studies on exceptional longevity often cannot be replicated," said Leonid Gavrilov, a research associate at the Center on Aging at the University of Chicago.

The study found a sex-specific increase in IGF-1; it showed up only among the daughters of centenarians, while sons were not affected, Gavrilov noted. "The study does not suggest any explanation, or even a hypothesis, for this sex-specific effect. General conclusions suggested in this paper may be questionable if they are not applicable to men," he said.

"It may be interesting to put this study in a context of other findings, such as being born to a young mother helps to live to 100 years," Gavrilov said.

More information

For more on aging, visit the National Institute on Aging.

SOURCES: Nir Barzilai, M.D., director, Institute for Aging Research, Albert Einstein College of Medicine, New York City; Leonid Gavrilov, Ph.D., research associate, Center on Aging at the University of Chicago; March 3-7, 2008, Proceedings of the National Academy of Sciences

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