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What Causes Cystic Fibrosis and What is the Prognosis?

Cystic Fibrosis is a genetic disease that is caused by a series of mutations in the gene that codifies a specific protein called ‘cystic fibrosis transmembrane conductance regulator’.

It’s a mouthful, so thankfully the scientific community has shortened it to ‘CFTR’.

The function of CFTR is to regulate the transport of chloride ions through the membranes of exocrine epithelial cells, such as sweat glands. If the CFTR being produced by our genes is faulty, so will be the regulation of transportation of chloride across cell membranes. This causes a diminished secretion of water, giving sweat with high viscosity as a consequence. Why is high viscosity of water an issue? Because the ducts through which water passes (like sweat) can become clogged due to the difficulty of water to exit.

Sweat is just the beginning of the issue. Think about the lungs, intestines, sex glands and pancreas! All of these depend on the secretion of fluids that allow the proper functioning of the organ.

Sweat glands are the most affected by cystic fibrosis. Sweat from someone suffering from this disease can bring with it a higher content of sodium chloride and this ‘salty’ characteristic is how cystic fibrosis is diagnosed.

Likewise, the mutation of the gene responsible for the codification of CFTR alters the different local defense mechanisms of some organs, such as the lungs. The respiratory tract contains natural amounts of lysozyme and lactoferrin, enzymes that act as antimicrobial agents. Their quantities are reduced if the concentration of sodium chloride is high. In this manner, there is an increased vulnerability to infection for those who suffer from cystic fibrosis.

Another mechanism that the respiratory tract uses to expel foreign matter from our lungs is by the use of tiny hair-like structures called cilia located in the mucosa of the tract. For example, when there is increased mucus production in the airways and it comes into contact with cilia, they stimulate a strong reaction from the lungs that we know as coughing. A person with cystic fibrosis will see the activity of cilia drop considerably.

The pancreas is another affected organ. It is postulated that the alteration in the concentration of chloride, bicarbonate and sodium, increases the viscosity of pancreatic secretions, causing obstruction slowly but surely and with it progressive self-destruction of the pancreas.

Finally, the mutation of the CFTR gene is the cause of blockage to the vas deferens ducts, which are vasa responsible for carrying sperm to the ejaculatory ducts in males. This is why cystic fibrosis is so often accompanied by sterility.

The prognosis for cystic fibrosis patients has improved dramatically over the last few years. In the 1950s, life expectancy was at a meager 4 years of age. Whereas in 2018, the life expectancy has increased to almost 40 years of age! The main reasons for this improvement are due to early diagnoses, betterment of nutritional habits and advances in the treatment of respiratory infections.

However, despite the achievements of the scientific community in this regard, the most frequent cause of death of cystic fibrosis sufferers tends to be associated with the malnutrition generated by the inadequate absorption of fatty acids and nutrients, due to pancreatic insufficiency, recurrence of respiratory infections and lack of appetite.

Other less frequent causes of death are meconium ileus, which is an intestinal blockage due to highly viscous meconium (like stool produced by a newborn), altered hepatic function and cardiac insufficiency.

Today, hope lies in the advancements being made by the transplant of organs. Not only are a high number of organs becoming more and more available for those in need, but also the continued improvement of surgical procedures and techniques, not to mention effective immunosuppressive drugs for after the transplant.

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