Rare type of dwarfism could hold the key to a longer life, scientists claim

A rare form of dwarfism has been found to protect individuals from cancer and diabetes, suggesting the gene could be the key to a longer life. 

Known as Laron syndrome, individuals with the condition stand about four feet because their bodies can't make use of their own growth hormone that is produced in the brain - but they have an average lifespan of those without the disorder.

Scientists who have followed a group of adults with Laron syndrome for almost 20 years have discovered how their rare condition can be a gift, protecting them from aging-related diseases - and potentially paving the way for anti-aging treatments. 

In the latest study on this group, a team of scientists from California and Ecuador found that people with Laron syndrome have lower blood sugar, insulin resistance, and blood pressure compared to their relatives who don't have the condition.

Doctors Jaime Guevara-Aguirre (back left) and Valter Longo (back right), pictured with several of the Laron study participants at the USC Leonard Davis School of Gerontology in Los Angeles. The two researchers have followed Laron syndrome individuals for years to find out what kinds of advantages their rare genetic syndrome gives them.

Ecuadoreans Maritza Valarezo (right) and her sister Lugartda (left), both have Laron syndrome. There are only about 400 to 500 people worldwide who are known to have the rare genetic condition.

The study participants were also found to have smaller hearts than their relatives, lower carotid artery thickness, and lower rates of arterial plaque - the substance that can narrow arteries and lead to heart attack, heart failure, or blood clots.

Doctors  first identified Laron syndrome among adults with dwarfism who live in a remote corner of Ecuador. It is also known as growth hormone receptor deficiency - GHRD for short. 

Laron syndrome individuals actually tend to have high levels of growth hormone, but their genetic mutation makes it so their body can't produce the target for the hormone.

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When co-lead study author Dr Jaime Guevara-Aguirre first started studying Laron syndrome, he was surprised that the condition seemed to protect against cancer.

After all, higher levels of growth hormone are usually linked to cancer - and this relationship has been reliable in most people.  

Guevara-Aguirre, an endocrinologist at the Universidad San Francisco de Quito, Ecuador, has been studying Laron dwarfism for more than 20 years, previously told DailyMail.com: 'We've discovered that people with Laron simply don't get cancer.

'Cancer can be detected in their relatives of a normal size, but never in my patients - not one single case,' he said.

Most of the people with Laron syndrome come from Ecuador, where the average heights for men and women - five-foot, six inches and five-foot and 1/2 inch - are among the shortest in the world.

For this reason, these individuals don't tend to think of themselves as particularly short. 

Women with Laron average around four feet tall, and men are usually around four feet, six inches.

But what many of them do realize is that they have a special biological gift.

'Since I was a teenager, I saw my height as (an opportunity) to develop — the growth problem is part of my personality,' Nathaly Paola Castro Torres told CNN in Spanish.

'I am also quite lucky because in reality my body protects me a lot from diseases that other people have every day,' she added. 'This height, at the same time as being a limitation, is also a blessing.'

Insulin-like growth factor 1 (IGF-1) is produced in the liver. In people with typical genetics (left), growth hormone from the brain's pituitary gland tells the liver to make more IGF-1, which can contribute to aging and age-related diseases. But in people with Laron syndrome (right), despite high levels of growth hormone, their liver produces much lower amounts of IGF-1, protecting them against heart disease.

Maritza (left) and Lugartda Valarezo (right), in their kitchen in Quito, Ecuador, in 2014. The Valarezo sisters are patients of co-lead study author Jaime Guevara-Aguirre, who has studied Laron syndrome for more than two decades.

Because of their resistance to chronic diseases, people with Laron syndrome have been the subject of great interest from doctors and scientists looking for treatments for aging-related diseases. 

'We have shown in studies people with Laron have a very low incidence of cancer, diabetes and cognitive decline,' said co-lead study author Dr Valter Longo, professor of gerontology at the University of Southern California. 

'Brain scans have shown they have more youthful brains - the equivalent of someone 20 years younger. I have yet to see a case of Alzheimer's in this population.' 

Some even claim that studying these patients will lead to cures for cancer and diabetes

'It doesn't mean that they are immune to these diseases, but people with Laron syndrome certainly seem to be very protected,' said Longo on the latest study on heart health. 'This is how powerful this mutation seems to be.' 

Based on the new study, the key seems to be a hormone called insulin-like growth factor 1 (IGF-1).

This chemical is produced mostly in the liver.

In people with typical genetics, growth hormone from the brain's pituitary gland gives the liver instructions to make more IGF-1, which supports normal wound healing and other metabolic processes.

High levels of IGF-1 can contribute to aging and age-related diseases, though.

In people with Laron syndrome, despite high levels of growth hormone, their liver produces much lower amounts of IGF-1, which seems to protect them against heart disease.

In mice, IGF-1 deficiency has led to heart disease, so the results of the new study were somewhat unexpected. 

Researchers also said that Laron syndrome individuals' low levels of IGF-1 in the blood contribute to reduced risk of cancer and diabetes, but more research is necessary to figure out the specifics of that connection.

'Although the population tested is small, together with studies in mice and other organisms this human data provide valuable insights into the health effects of growth hormone receptor deficiency and suggest that drugs or dietary interventions that cause similar effects could reduce disease incidence and possibly extend longevity,' Longo said. 

The study was published in the journal Med.