What Is Cystic Fibrosis?
Cystic fibrosis is a progressive, genetic disease that causes persistent lung infections and limits the ability to breathe over time. In people with CF, mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause the CFTR protein to become dysfunctional. When the protein is not working correctly, it’s unable to help move chloride — a component of salt — to the cell surface. Without the chloride to attract water to the cell surface, the mucus in various organs becomes thick and sticky.
In the lungs, the mucus clogs the airways and traps germs, like bacteria, leading to infections, inflammation, respiratory failure, and other complications. For this reason, minimizing contact with germs is a top concern for people with CF.
In the pancreas, the buildup of mucus prevents the release of digestive enzymes that help the body absorb food and key nutrients, resulting in malnutrition and poor growth. In the liver, the thick mucus can block the bile duct, causing liver disease. In men, CF can affect their ability to have children.
Symptoms of CF
People with CF can have a variety of symptoms, including:
- Very salty-tasting skin
- Persistent coughing, at times with phlegm
- Frequent lung infections including pneumonia or bronchitis
- Wheezing or shortness of breath
- Poor growth or weight gain in spite of a good appetite
- Frequent greasy, bulky stools or difficulty with bowel movements
- Male infertility
Diagnosis and Genetics
Cystic fibrosis is a genetic disease. People with CF have inherited two copies of the defective CF gene — one copy from each parent. Both parents must have at least one copy of the defective gene.
People with only one copy of the defective CF gene are called carriers, but they do not have the disease. Each time two CF carriers have a child, the chances are:
- 25 percent (1 in 4) the child will have CF
- 50 percent (1 in 2) the child will be a carrier but will not have CF
- 25 percent (1 in 4) the child will not be a carrier and will not have CF
The defective CF gene contains a slight abnormality called a mutation. There are more than 1,700 known mutations of the disease. Most genetic tests only screen for the most common CF mutations. Therefore, the test results may indicate a person who is a carrier of the CF gene is not a carrier.
Diagnosing cystic fibrosis is a multistep process, and should include a newborn screening, a sweat test, a genetic or carrier test, and a clinical evaluation at a CF Foundation-accredited care center. Although most people are diagnosed with CF by the age of 2, some are diagnosed as adults. A CF specialist can order a sweat test and recommend additional testing to confirm a CF diagnosis.
According to the Cystic Fibrosis Foundation Patient Registry, in the United States:
- More than 30,000 people are living with cystic fibrosis (more than 70,000 worldwide).
- Approximately 1,000 new cases of CF are diagnosed each year.
- More than 75 percent of people with CF are diagnosed by age 2.
- More than half of the CF population is age 18 or older.
The type and severity of CF symptoms can differ widely from person to person. Therefore, although treatment plans can contain many of the same elements, they are tailored to each individual’s unique circumstances.
Each day, people with CF complete a combination of the following therapies:
- Airway clearance to help loosen and get rid of the thick mucus that can build up in the lungs.
- Inhaled medicines to open the airways or thin the mucus. These are liquid medicines that are made into a mist or aerosol and then inhaled through a nebulizer and include antibiotics to fight lung infections and therapies to help keep the airways clear.
- Pancreatic enzyme supplement capsules to improve the absorption of vital nutrients. These supplements are taken with every meal and most snacks. People with CF also usually take multivitamins.
- An individualized fitness plan to help improve energy, lung function, and overall health
- CFTR modulators to target the underlying defect in the CFTR protein. Because different mutations cause different defects in the protein, the medications that have been developed so far are effective only in people with specific mutations.
Cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapies are designed to correct the malfunctioning protein made by the CFTR gene. Because different mutations cause different defects in the protein, the medications that have been developed so far are effective only in people with specific mutations. There are four CFTR modulators for people with certain CFTR mutations:
- Kalydeco® (ivacaftor)
- Orkambi® (lumacaftor/ivacaftor)
- Symdeko® (tezacaftor/ivacaftor)
- Trikafta® (elexacaftor/tezacaftor/ivacaftor)
More potential CFTR modulators are in development to address the underlying cause of the disease in people with other CF mutations.
The CFTR protein regulates the proper flow of water and chloride in and out of cells lining the lungs and other organs. In people with CF, mutations in the CFTR gene result in either a defective protein being produced or no protein at all. This leads to the buildup of thick, sticky mucus, which can lead to infections in the lungs and damage to the pancreas. It can also lead to problems in other parts of the body.