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Scientists have discovered a group of people with a rare gene mutation that protects them from cancer and diabetes. The mutation also keeps them from growing taller than a typical third grader. Researchers say this discovery could lead to new ways of preventing deadly diseases associated with aging. NPR's Jon Hamilton reports.
JON HAMILTON: The journey began more than 15 years ago in a lab in Los Angeles. A graduate student named Valter Longo was studying yeast. He was hoping to learn something that might help humans live longer, healthier lives. Longo, who is now a professor at USC, says his research led him, first, to a particular type of genetic mutation. Ultimately, it took him to the mountains of southern Ecuador to study people with something called Laron syndrome.
Professor VALTER LONGO (University of Southern California): They're very short - most of them less than four feet tall. And they're generally normal. Some of them have families. And they seem to be pretty happy, very intelligent. Just small - yes.
HAMILTON: Longo says another scientist had noticed something surprising about these people. They didn't seem to get diseases associated with aging.
Prof. LONGO: Even though they have an increased obesity, none of them have ever developed diabetes.
HAMILTON: And when Longo and a team of researchers studied decades of medical records on 99 of these people, they found that only one got cancer. That was a much lower rate of cancer than among their taller relatives.
The team thought this protection might come from the same gene mutation that made these people so small. It's a mutation that keeps cells from responding to growth hormone. Longo knew that a similar mutation greatly extends the life spans of yeasts and worms and rodents. And he had suspected that it might work that way in people, too.
Prof. LONGO: There was only one major piece missing, which was the human data. And this is it, you know.
HAMILTON: Longo says the mutation seems to prevent diabetes by allowing people to get by on very low levels of insulin. It wards off cancer by reducing DNA damage in cells and helping to eliminate abnormal cells. Longo says you'd expect all this protection to allow the small people in Ecuador to live longer than their taller relatives. They don't.
Prof. LONGO: The majority of them die of just strange causes, including alcohol related deaths, accidents, et cetera.
HAMILTON: Things that have nothing to do with disease. Subtract the presentable deaths, Longo says, and it looks like they really would live longer than their relatives.
Longo says his study is good news. He says a whole lot of people might be able to lower their risk of cancer and diabetes if they could lower their levels of growth hormone.
Robert Salvatori, of Johns Hopkins University in Baltimore, agrees. He studied a group of small people in northeast Brazil whose bodies don't produce growth hormone at all. He says they also appear less susceptible to diseases associated with aging. Salvatori says people taking growth hormone for medical reasons shouldn't be concerned by the new study. For example, he says there's good scientific evidence that children who are prescribed growth hormone to reach normal height are not at increased risk of cancer.
Dr. ROBERT SALVATORI (Johns Hopkins University): So I think that, you know, parents should not worry too much about this.
HAMILTON: But Salvatori says athletes or others who are taking large doses of growth hormone to build muscle should take the new study as a warning.
Dr. SALVATORI: If lacking growth hormone is associated with lack of cancer one could sort of assume that excessive growth hormone may be associated with increased cancer. So, you know, certainly, it's a worry.
HAMILTON: The new research appears in the journal, Science Translational Medicine.
Jon Hamilton, NPR News.
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