They’re about three and a half feet tall and their origins are mysterious, but an isolated group of Ecuadorians with a genetic mutation causing dwarfism are making news for another reason: They hardly ever get cancer or diabetes. Medical researchers say the villagers’ genetic protection from these diseases could lead to preventative treatments for the general population–and could therefore increase human longevity.
The villagers’ condition is called Laron syndrome, which is caused by an insensitivity to growth hormone.
Laron syndrome results from a mutation in the gene that codes for growth hormone receptor (GHR), a protein that binds with the human growth hormone and ultimately results in the production of the insulin-like growth factor 1 (IGF1), causing cells to grow and divide. When a person has two of these mutated and non-working genes, they can develop the disease. [LiveScience]
Jaime Guevara-Aguirre, the leader of the study about the Ecuadorians appearing in Science Translational Medicine, has been looking into their condition and extraordinary resistance to age-related diseases for more than two decades, since his serendipitous discovery of the people while riding horseback in Ecuador.
“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.” [The New York Times]
Longo is the aging expert and study coauthor with whom Guevara-Aguirre began to investigate why these villagers appeared to be diabetes- and cancer-free. First, they had to compare them to nearby Ecuadorians who lived in the same kind of environment but didn’t have Laron syndrome.
The team followed about 100 people with the syndrome, and 1,600 normal-sized relatives in nearby towns. Over 22 years, there were no cases of diabetes and only one non-lethal case of cancer among the Laron group. Among the relatives, about 5 percent developed diabetes and 17 percent developed cancer. [Reuters]
The researchers noted that the Laron patients aren’t producing insulin-like growth factor 1 (IGF1), which has been shown to play a role in longevity–in one animal study, researchers found that worms lacking an IGF1 gene lived twice as long as normal. Guevara-Aguirre believes that lack of IGF1 is responsible for the Laron patients’ remarkable resistance to cancer and diabetes. From the study:
Family members with the gene mutation have lower amounts of Insulin-like Growth Factor 1 or IGF-I, as well as lower insulin concentrations and higher insulin sensitivity. And when stressed, their cells tend to self-destruct rather than accumulate DNA damage. All of these features are known to promote longevity in lower organisms. Although it’s difficult to prove that major reductions in IGF-I and insulin concentrations are responsible for the lack of cancer and diabetes in this Ecuadorian family, the findings coincide with similar observations in lower organisms like yeast, worms and mice.
Unfortunately for the villagers, alcoholism, accidents, and other killers strike their population at a high rate, so their resistance to cancer and diabetes does not afford them special longevity. Fortunately for humanity, however, their peculiar physiology could reveal ways to perhaps block excess growth hormones levels as a way to fight the deadly diseases that spare the villagers.
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Image: Science Translational Medicine (some members of Ecuadorian group in 1988, and then 2009)