Over a course of 22 years, a study of dwarfs has shown a relation between growth inhibiting genes and variants related to both diabetes and cancer. Biologists from the University of Southern California (USC) and Ecuadorian endocrinologist Jaime Guevara-Aguirre, followed a remote Andes mountain community of about 100 such individuals and 1,600 relatives of normal stature. No cases of diabetes and only one benign case of cancer were documented over the years. In addition, a new statin to fight cardiovascular disease may have been uncovered.

Valter Longo from USC states:

“The growth hormone receptor deficient people don’t get two of the major diseases of aging. 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. Although all the growth hormone deficient subjects we met appear to be relatively happy and normal and are known to have normal cognitive function, there are a lot of strange causes of death, including many that are alcohol-related.”

If high growth factor levels become a risk factor for cancer as cholesterol is a risk factor for cardiovascular diseases, drugs that reduce the growth factor could become the new statins according to Longo.

Statins are a class of drug used to lower cholesterol levels by inhibiting the enzyme HMG-CoA reductase, which plays a central role in the production of cholesterol in the liver. Increased cholesterol levels have been associated with cardiovascular diseases (CVD), and statins are therefore used in the prevention of these diseases.

Such drugs would be used at first only for families with a very high incidence of cancer or diabetes and because growth hormone activity decreases naturally with age, any preventive treatment would be appropriate only until the effects of advanced age took over.

The FDA has already approved drugs that block growth hormone activity in humans. These are used to treat acromegaly, a condition related to gigantism. Exactly how growth hormone deficiency might protect a person is not fully understood. Artificial hormone blocking is not the only way to reduce these hormones in humans.

A natural method appears to achieve the same effect: restriction of calories or of specific components of the diet such as proteins. The results are not yet known, but a recent study by Longo’s group showed that fasting induces rapid changes in growth factors similar to those caused by the Laron mutation. Laron syndrome, or Laron-type dwarfism, is an autosomal recessive disorder characterized by an insensitivity to growth hormone (GH), caused by a variant of the growth hormone receptor. It causes short stature.

Because fasting or restriction in particular nutrients for long periods can lead to dangerous conditions including anorexia, reduced blood pressure and immunosuppression, and because individuals with rare genetic mutations can suffer life-threatening effects from even short periods of fasting, the study emphasized that additional studies are needed and that any changes in diet must be approved and monitored by a physician.

Co-author Guevara-Aguirre wanted to understand the reasons for the stunted growth of children in the remote community, centered in the Loja province of southern Ecuador, where she began to notice that the adults in the community were not dying of the usual chronic diseases.

After hearing of the Ecuador study findings, Longo invited Guevara-Aguirre to present at a symposium on aging and cancer in 2006 at USC’s Leonard Davis School of Gerontology, where Longo is associate professor.

Together, they obtained funding from the Center of Excellence in Genomic Science in the USC College of Letters, Arts and Sciences, which sponsored part of the initial field research in Ecuador, and from the National Institute on Aging, which sponsored the cellular studies.

Dwarfism can be caused by about 200 distinct medical conditions, such that the symptoms and characteristics of individual people with dwarfism vary greatly. In the United States, Canada and New Zealand, many people with dwarfism prefer to be called little people.

Short stature can be inherited without any coexisting disease. Short stature in the absence of any abnormal medical condition is not generally considered dwarfism. For example, a short man and a short woman who are in normal health will tend to produce children who are also short and in normal health. While short parents tend to produce short children, persons with dwarfism may produce children of normal height, if the cause of their dwarfism is not genetically transmissible or if the individual does not pass on the genetic mutation.

Source: Science Translational Medicine

Written by Sy Kraft, B.A.