What happens in cystic fibrosis, exactly?

What is it?

Cystic fibrosis is a genetic disorder that affects primarily the lungs. The formation of sticky mucus leads to issues like recurrent infections and inflammations of the chest, as well as frequent coughing and difficulty with breathing. The mucus can also block parts of the digestive system leading to a variety of problems.

In 2010, the median age of survival of people with cystic fibrosis was 37 for women and 40 for men. A rough estimate is that 1 in 3000 Western children are born with cystic fibrosis, but this varies a lot by area.

What causes it?

Cystic fibrosis is caused by a faulty gene. Genes are the instructions for proteins, and the symptoms of cystic fibrosis are caused by the inability to produce a certain functioning protein. Only one correctly functioning gene is needed in order to produce the correct protein; this means that you need two copies of the faulty gene, one from each of your parents, to be affected.

What happens during it?

The faulty protein acts normally as a channel in the cell membrane. It allows chloride (a negatively charged ion) to pass between the inside of the cell and its environment. Opposite charges attract each other, and when chloride gets “stuck” inside the cell, it attracts sodium and together they form NaCl, commonly known as salt. This causes the heightened levels of salt in the sweat of people with cystic fibrosis.

Water is not a charged molecule, but since oxygen pulls electrons with much more strength than hydrogen does, the result is that the oxygen end of a water molecule is slightly negatively charged, while the hydrogen end of it it slightly positively charged. This polarity allows water to make strong bonds with ions. The increased levels of chloride thus also cause water to be pulled inside the cell.

Mucus is mostly made out of water. When the cells that secrete mucus keep the water inside themselves, the mucus gets thick and sticky. This leads to many problems: the mucus doesn’t flow away when it’s time for it to be replaced by new mucus, and the accumulation of it can disturb the functions of many organs and cause infections in them. This is particularly dangerous in the lungs. The mucus blocks small airways, and also acts as a perfect environment for many bacteria; the thick mucus is nutrient-rich, and a good place to hide from the immune system.

How can it be treated?

There is currently no treatment for cystic fibrosis, but a lot can be done to improve the quality of life of the affected. Preventing airway inflammation is often thought to be the most important thing. This can be done by, for example, using antibiotics as well as medication that makes the mucus thinner. Some breathing techniques can help to clear the mucus out of the lungs.

Cystic fibrosis is often accompanied by problems with food digestion and absorption. The affected need to pay careful attention to getting enough nutrients. This can be supported by taking digestive enzyme capsules to make the breaking down of food more efficient.

Since cystic fibrosis is caused by one faulty gene, there is hope that it can be fully cured in the future by using the new gene technology (CRISPR, for example) that is currently under rigorous research.



Sources: https://en.wikipedia.org/wiki/Cystic_fibrosis#Epidemiology, https://fi.wikipedia.org/wiki/Kystinen_fibroosi, http://www.nhs.uk/Conditions/cystic-fibrosis/Pages/Treatment.aspx, http://emedicine.medscape.com/article/1001602-overview?pa=dJTpVlsoEGwZMvHq4Q6yi5cwORIy42we7c0coANFPU4VzlCaolo2QO2nQzAc8tre56MI7dGTgNawPfsOtJla9Q%3D%3D#a3



3 thoughts on “What happens in cystic fibrosis, exactly?

  1. Great post! I also just wanted to mention that mutations in the cystic fibrosis transmembrane regulator protein (CFTR) also can cause the protein’s degradation in the ER, even before reaching the apical plasma membrane and thus inducing cystic fibrosis due to the protein’s non-presence. Looking forward to more of your posts 🙂


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