Being Short Not That Bad- Are Very Short People Protected From Diabetes And Cancer?
This week Science Translational Medicine published provocative results from an Eucador study that people who are genetically short may be protected from diabetes and cancer. These patients had a genetic mutation that would not allow them to grow more than 4 feet tall -- their heights would be fixed to that of a 7-year-old for life.
The study was prompted by earlier research reports in animal models that showed an extension of life span in yeast and resistance to insulin resistance and cancer in the mouse.
To test the effect in humans, the authros monitored for 22 years Ecuadorian individuals who carry mutations in the growth hormone receptor (GHR) gene that lead to severe GHR and IGF-1 (insulin-like growth factor–1) deficiencies.
The study published Wednesday in Science Translational Medicine monitored a group of 99 Ecuadorians -- described as being of "severe short stature." The mechanisms that stunt their growth could potentially prevent cancer and diabetes, according to the findings.
Guevara-Aguirre and the co-authors compared the living participants' health with that of their close relatives who were of regular height. Those blood relatives "developed diabetes like the general Ecuadorian population, about 20% of them have died of cancer," Guevara-Aguirre said.
Yet of all the severely short patients only one got cancer in the 22-year period. After receiving treatment for ovarian cancer in 2008, she has remained cancer-free.
Researchers also looked at detailed death information on 53 severely short people who were not part of the study. They found no evidence of cancer or diabetes-related deaths there.
Despite this resistance to diabetes or cancer, life expectancy of the study subjects didn't rise.
"The answer is, it doesn't lead to life extension," said Dr. Valter Longo, one of the authors in the study. "It leads to major reduction in cancer and diabetes."
During the course of the study, nine of the 99 participants with dwarfism died. Their common killers were age-related diseases such as heart disease and stroke. Compared with their relatives of regular height, they "died much more frequently from accidents, alcohol-related causes, and convulsive disorders," according to the study.
"They do have potential to live longer if they don't die of weird causes of death-accidents, alcohol-related conditions," said Longo, an associate professor of biological sciences at the University of Southern California.
Dwarfism can be caused by several factors, including genetics, kidney disease or hormones.
The severely short Ecuadorians in the study have a specific mutation in their growth hormone receptor gene.
Although their pituitary glands produce enough growth hormones, their receptors are missing. That inability to bind to receptors means another growth hormone, called insulin-like growth factor-1 is not well-produced. This condition is known as Laron syndrome.
The affected Ecuadorians are descendants of Spanish Jews who escaped to South America to avoid the Inquisition and converted to Christianity, according to the researchers. The mutation is prevalent in this gene pool.
The findings from this study raise questions about the relationship between growth hormones and diseases.
"We treat adults who become growth hormone deficient with growth hormones. Studies like this, makes us pause," said Dr. Roberto Salvatori, associate professor of medicine in the division of endocrinology and metabolism at Johns Hopkins University
Courtesy: CNN, Yahoo News and Science Translational Medicine