Dwarfism gene may help prevent cancer, diabetes
The long-term study, published in the journal Science Translational Medicine, raised the prospect of achieving similar protection in full-grown adults by other means, such as drugs or controlled diets.
The international team, led by Valter Longo of the University of Southern California and endocrinologist Jaime Guevara-Aguirre of Ecuador, followed a remote community on the slopes of the Andes mountains in the South American country.
The draft community includes many members with Laron syndrome — a deficiency in a gene that prevents the body from using growth hormone.
The team followed about 100 such individuals and 1,600 relatives of normal stature for over 22 years. And during the period, the team could not find a single case of diabetes while only one non-lethal case of cancer was documented.
However, among relatives living in the same towns during the same time period, 5 per cent were diagnosed with diabetes and 17 per cent with cancer.
Because other environmental and genetic risk factors are assumed to be the same for both groups, the researchers concluded that, at least for adults past their growing years, growth hormone activity has many downsides.
"The growth hormone receptor-deficient people don`t get two of the major diseases of ageing. They also have a very low incidence of stroke, but the number of deaths from stroke is too small to determine whether it`s significant," Longo said.
Overall lifespan for both groups was about the same, with the abnormally short subjects dying more often from substance abuse and accidents. The study did not include psychological assessments that could have helped explain the difference, said the researchers.
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.
Longo`s team found that in the Ecuadorean group, the deficient GHR led to low levels of IGF1, and this was associated with the disease-resistance.
The researchers are now planning to run clinical trials with IGF1-lowering drugs on cancer patients undergoing chemotherapy.
By decreasing IGF1 levels in these patients to normal levels, they will be able to see if they are protected from further effects of the disease.