Science

Beating genetic diseases: tackling cystic fibrosis head on

By Samuel Durley

A drug that treats the very causes of cystic fibrosis has fulfilled a promise made more than 20 years ago by scientists who identified the gene that is responsible for the disease.

Researchers have reported in the scientific journal, Nature, on a clinical trial testing Kalydeco, a drug designed to treat cystic fibrosis at the very smallest of molecular levels.

Cystic fibrosis is a genetic disease that affects about 1 in 3500 people and is the most commonly inherited disease in the UK. Sufferers of cystic fibrosis have two mutated copies of the gene that causes cystic the disease; about one in 25 people in the UK carry one mutated gene.

Incredible research since the 1980s has increased the life expectancy for this disease from only 14 years to around 35 years in the current day. These treatments have until now only addressed the symptoms of the disease rather than the very cause.

The symptoms of cystic fibrosis are a thickening of the mucus that lines the lungs and digestive system. This thicker mucus is a haven for infectious diseases which often leads to severe infections of the lungs or digestive tract that result in the death of the sufferer.

The gene that involved in this disease is responsible for maintaining the balance of salt inside the cells that line the lungs by making a small hole, or channel, in the wall of the cell. When the gene is mutated this channel does not work properly causing salt, and ultimately water, to become trapped inside the cell and this is what causes the mucus to become thicker.

One mutation that results in cystic fibrosis means that the channel does not open properly. The drug Kalydeco however addresses this very problem by sticking to this channel and causing it to open. This rebalances the amount of salt and water and causes the mucus to become less thick, reducing the chance of infection.

Unfortunately there are as many as 1500 different mutations of the cystic fibrosis gene  and the mutation that Kalydeco addresses makes up four percent of those found in patients. This may sound like a small number but in reality it can change thousands of lives. And there is further hope.

A mutation that affects about 90 percent of cystic fibrosis sufferers that causes the channel to be destroyed when it is made has been heavily studied and promisingly a drug called VX-809 is now in trials to solve this problem too.

All of this shows the remarkable progress in scientific research and ingenuity over the last 20 years in tackling this genetic disease. Mathhew Reed, the chief executive of the Cystic Fibrosis Trust in London said “this is a seminal turning point in the treatment of cystic fibrosis.”

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