Cystic fibrosis is a genetic (inherited) condition that causes severe damage to the lungs, digestive system and other organs in the body. The mucus normally secreted by cells in the lung airways (breathing tubes), pancreatic ducts, gastrointestinal tract, and the reproductive system becomes thickened and blocked, causing frequent infections and loss of function in the affected organs.

Key Facts

  • Cystic fibrosis is a life-threatening, genetic condition.
  • Both parents have to be carriers of an abnormal gene that gets passed on to their child for the child to have CF.
  • People with this condition produce a faulty CFTR protein that affects the cells of the body that produce mucus and sweat.
  • There are about 30,000 people with cystic fibrosis in the United States and approximately 70,000 people worldwide. Approximately 1 in 30 Americans is a carrier.
  • There is no cure for CF, but treatment is available. Because of improved care, the average life expectancy has been steadily increasing since the 1950s and is currently close to 40 years.
  • It is most common in Caucasians.

How Cystic Fibrosis Affects Your Body

Patients with CF suffer from a cystic fibrosis transmembrane conductance regulator (CFTR) gene mutation, which causes the CFTR protein to malfunction. The CFTR protein is located in every organ of the body that makes mucus; including the lungs, liver, pancreas, intestines and sweat glands. It is also present in many other cells in the body. When the CFTR protein isn’t working correctly, thick, sticky mucus is produced that causes blockages and traps germs, leading to infections.

In the lungs, this thick mucus can obstruct (clog) the airways. The mucus creates an environment for bacteria to grow, causing infections and further inflammation. Over time, this damages the airways and eventually the lung tissue, which can lead to respiratory failure. This vicious cycle is also why people with cystic fibrosis are more susceptible to developing other chronic infections including bronchitis, bronchiectasis, pneumonia, hemoptysis (coughing up blood), nasal polyps and pneumothorax (collapsed lung), to name a few.

Many other organs in the body are affected by the CFTR protein malfunction. Scarring, caused by blocked ducts in the pancreas, leads to reduced absorption of fat and vitamins. In the digestive tract, intestinal secretions can become much thicker than normal, causing blockages that may require surgery. In the liver, ducts can be blocked causing damage to the liver cells and cirrhosis. In the reproductive tract, increased mucus can cause decreased fertility or infertility in both men and women.

What Causes Cystic Fibrosis?

CF is an inherited disorder caused by having two abnormal copies of the CF gene. You cannot catch or acquire CF. It can occur in people who have no known family history of the disease because people with one abnormal CF gene (called “carriers”) are usually healthy.

Who Is at Risk?

The only risk factor for getting CF is having two parents who carry abnormal CF genes and pass the abnormal gene on to their child. However, some factors impact how severe the CF is.

  • Genes: CF gene mutations are divided into classes based on how damaged the CFTR protein function is. Classes I, II and III are generally more severe causing “classic CF.” Classes IV and V are usually milder. Also, other genes called modifier genes can affect a person’s symptoms and outcome.
  • Environment and lifestyle: People with CF need to consume a very large number of calories to maintain weight and grow, which can be difficult to achieve. Physical activity is also important to help keep lungs healthy. People with CF should not smoke or be exposed to secondhand smoke, as it will worsen lung disease. You should also be careful with alcohol intake and avoid it altogether if you have liver disease.
  • Age: CF worsens with age. If you have CF, you usually experience a small decline in lung function each year.

Reviewed and approved by the American Lung Association Scientific and Medical Editorial Review Panel.

Page last updated: March 4, 2020

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