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From NY Time 2-16-2011

Ecuadorean Villagers May Hold Secret to Longevity
By NICHOLAS WADE

People living in remote villages in Ecuador have a mutation that some biologists say may throw light on human longevity and ways to increase it.

The villagers are very small, generally less than three and a half feet tall, and have a rare condition known as Laron syndrome or Laron-type dwarfism. They are probably the descendants of conversos, Sephardic Jews from Spain and Portugal who were forced to convert to Christianity in the 1490s but were nonetheless persecuted in the Inquisition. They are also almost completely free of two age-related diseases, cancer and diabetes.

A group of 99 villagers with Laron syndrome has been studied for 24 years by Dr. Jaime Guevara-Aguirre, an Ecuadorean physician and diabetes specialist. He discovered them when traveling on horseback to a roadless mountain village. Most such villages are inhabited by Indians, but these were Europeans, with Spanish surnames typical of conversos.

As Dr. Guevara-Aguirre accumulated health data on his patients, he noticed a remarkable pattern: though cancer was frequent among people who did not have the Laron mutation, those who did have it almost never got cancer. And they never developed diabetes, even though many were obese, which often brings on the condition.

“I discovered the population in 1987,” Dr. Guevara-Aguirre said in an interview from Ecuador. “In 1994, I noticed these patients were not having cancer, compared with their relatives. People told me they are too few people to make any assumption. People said, ‘You have to wait 10 years,’ so I waited. No one believed me until I got to Valter Longo in 2005.”

Valter D. Longo, a researcher on aging at the University of Southern California, saw the patients as providing an opportunity to explore in people the genetic mutations that researchers had found could make laboratory animals live much longer than usual.

The Laron patients have a mutation in the gene that makes the receptor for growth hormone. The receptor is a protein embedded in the membrane of cells. Its outside region is recognized by growth hormone circulating through the body; the inside region sends signals through the cell when growth hormone triggers the receptor.

For more details refer to: 

http://www.nytimes.com/2011/02/17/science/17longevity.html?_r=1&ref=health