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    New Clues on What Causes Aging

    Genetics and DNA Damage Play Role, Researchers Say
    WebMD Health News
    Reviewed by Louise Chang, MD

    Dec. 20, 2006 -- Ever wondered what causes aging? The answer may lie in DNA.

    DNA damage contributes to aging -- especially in people whose genes aren't good at repairing damage, researchers report in Nature.

    "Damage, including DNA damage, drives the functional decline we all experience as we age," says researcher Laura Niedernhofer, MD, PhD, in a news release.

    "But how we respond to that damage is determined genetically," continues Niedernhofer, an assistant professor of molecular genetics and biochemistry at the University of Pittsburgh.

    DNA can be damaged by normal wear and tear, as well as from smoking, too much sunlight, or other factors.

    "The bottom line is that avoiding or reducing DNA damage caused by sources such as sunlight and cigarette smoke, as well as by our own metabolism, also could delay aging," Niedernhofer says.

    Boy Is Clue to What Causes Aging

    One of Niederhofer's colleagues on the study was Jan Hoeijmakers, PhD, of Erasmus Medical Center in Rotterdam, Netherlands.

    Hoeijmakers had heard from doctors in Germany about a 15-year-old Afghan boy with an extreme form of premature aging, a condition called progeria.

    The boy was extremely sensitive to sunlight and had had an old, wizened appearance since age 10.

    He was gaunt, had hearing loss and vision problems, and had had hepatitisA and tuberculosis as a young child.

    The boy died when he was 16 after getting severe pneumonia and having organ failure. Genetic tests showed the boy had a severe mutation in his XPF gene, a gene involved in DNA repair.

    Lab Tests

    Based on those findings, Niedernhofer and colleagues studied a mouse model of the aging condition. They manipulated mice genetically to mimic the rapid aging effect of the XPF mutation seen in the boy.

    This doesn't mean the XPF gene is the only gene involved in progeria or in normal aging.

    "However, it shows how important it is to repair damage that is constantly inflicted on our genes," Hoeijmakers says in the news release.

    "It is fast becoming clear that unraveling the complex biology of aging so as to understand the true relationship between cause and effect will not be easy," writes editorialist Tom Kirkwood, PhD.

    Kirkwood works in England at Newcastle University's Institute for Ageing and Health.

    The XPF gene finding doesn't settle all the questions about aging, but it "represents a helpful buoy in these waters," Kirkwood writes.

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