Rising obesity levels are leading to an increase in cases of cancer, diabetes, and other health issues. However, a study that has continued over several decades has shown that individuals with a certain type of genetic dwarfism may be immune to these illnesses.

Cancer is caused by uncontrolled cell division, and an overabundance of growth hormone will trigger this excessive growth, which leads to tumors. Typically, dwarfism is caused by a lack of these hormones. However, individuals with Laron syndrome, named after endocrinologist Zvi Laron, have higher than normal levels of growth hormone, but they also have defective receptors that cannot respond to the hormones. Because of this, the chemical pathway that tells the cells to divide isn’t started, leading to the small stature.

Further research of a small population of people with Laron syndrome in the Loja province of Ecuador showed that all but one of the 38 DNA samples showed a mutation in the growth hormone receptor. A patient of Moroccan and Jewish descent also had the same receptor mutation, suggesting that a common ancestor lived in the Iberian Peninsula and fled during the Spanish Inquisition.

The lack of functional growth hormone receptors explains how very few people with Laron syndrome have cancer: the cells can’t reproduce out of control if they can’t receive the signal to grow. However, very few also had diabetes, which should have been more prevalent considering their predisposition to obesity. Instead, the researchers found that those with Laron syndrome had a higher sensitivity to insulin rather than the lower sensitivity or resistance found in other overweight people.

With this knowledge, scientists are looking into whether defective growth hormone receptors or increased insulin sensitivity affects the likelihood of other diseases in individuals with Laron syndrome. These findings could lead to medicines that mimic these processes to beat cancer, diabetes, and more.