Baku, February 18 (AZERTAC). 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 3½ feet tall, and have a rare condition known as Laron syndrome or Laron-type dwarfism. 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. As Guevara-Aguirre accumulated health data on his patients, he noticed a remarkable pattern: People who have the Laron mutation almost never got cancer. And they never developed diabetes, even though many were obese, which often brings on the condition.

Valter Longo, a researcher at the University of Southern California, saw the patients as providing an opportunity to explore 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.

The Laron patients` mutation means their growth hormone receptor lacks certain units of its exterior region, so it cannot react to growth hormone, and does not as a result produce another insulin-like hormone involved in growth.

This is where the physiology of the Laron patients links up with the studies researchers have been pursuing with animals. Longo said he believed that having very low levels of the insulin-like hormone was the critical feature of the Laron patients` freedom from age-related diseases.

The two physicians reported their findings on Wednesday in Science Translational Medicine.