Cystic fibrosis (CF) is a genetic condition that affects a protein in the body. People who have cystic fibrosis have a faulty protein that affects the body’s cells, its tissues, and the glands that make mucus and sweat.
Normal mucus is slippery and protects the airways, digestive tract, and other organs and tissues. Cystic fibrosis causes mucus to become thick and sticky. As mucus builds up, it can cause blockages, damage, or infections in affected organs.
Cystic fibrosis used to cause death in childhood. Survival has improved because of medical discoveries and advances in newborn screening, medicines, nutrition, and lung transplants. Nearly 40,000 children and adults in the United States and more than 100,000 worldwide are now living with cystic fibrosis. Children born between 2018 and 2022 who have cystic fibrosis are expected to live an average of 56 years. On average, half of babies born in 2021 with cystic fibrosis are expected to reach the age of 65 or older.
Many people believe that only people who are white get cystic fibrosis. But the disease can occur in anyone and sometimes gets missed in people who are Black.
Although medical advances mean that more people with cystic fibrosis live into adulthood, not everyone gets the same benefits. For example, having a low income is linked with worse lung function, higher death rates, and poorer nutritional status for people with cystic fibrosis. This is true even when comparing groups that have the same number of healthcare visits and take long-term prescription medicines. Also, people of color are more likely to be diagnosed.
Cystic fibrosis is an inherited disease caused by mutations in a gene called the cystic fibrosis transmembrane conductance regulator (CFTR). The CFTR gene provides instructions for the CFTR protein.
People who inherit two copies of a mutated CFTR gene (one copy from each biological parent) will have cystic fibrosis. Having two mutated CFTR genes means that the body makes a CFTR protein that doesn’t work like it should.
In cystic fibrosis, the mutated CFTR gene changes a protein that regulates the movement of salt in and out of cells. These changes cause thick and sticky mucus and increase the amount of salt in sweat. The abnormal mucus can lead to blockages in and damage to the lungs, the digestive system, and other organs of the body.
Normally, mucus coats tiny hairlike structures called cilia in the airways of your lungs. The cilia sweep the mucus particles up to the nose and mouth so your body can get rid of them. In people who have cystic fibrosis, this process does not work well.
More than 2,000 mutations of the CFTR gene can cause cystic fibrosis. Different mutations affect how much CFTR protein the cells make and how well the protein works. With the most common gene mutation, part of the CFTR gene is missing. The mutation makes a CFTR protein that can’t stay in the correct shape. Some CFTR mutations cause cells to make hardly any CFTR protein at all.
Normally, CFTR protein controls the movement of ions from inside the cell to outside the cell. In people who have cystic fibrosis, the CFTR protein does not work properly. The faulty CFTR protein affects how sodium and water move in and out of cells. Mucus becomes thick and sticky, because it contains less water. Also, sweat glands in the skin make extra-salty sweat.
Every person inherits two CFTR genes: one gene from each parent. Children who inherit a CFTR gene with a mutation from each parent will have cystic fibrosis.
When a mutated CFTR gene is inherited from one parent and a normal CFTR gene is inherited from the other, the person will be a cystic fibrosis carrier. Cystic fibrosis carriers can pass the mutated CFTR gene on to their children. Carriers are generally healthy, but they may have some mild symptoms of cystic fibrosis.
The image below shows how two parents who are both cystic fibrosis carriers can pass a CFTR gene mutation on to their children.
If both parents have a normal CFTR gene and a mutated CFTR gene, each of their children has a:
Some people who have cystic fibrosis have few or no symptoms, while others experience severe symptoms or life-threatening complications. The most serious and common complications of cystic fibrosis are problems with the lungs, including frequent pulmonary or respiratory exacerbations, typically caused by serious lung infections.
Diagnosing cystic fibrosis takes several steps. Your healthcare provider may diagnose cystic fibrosis based on your symptoms and results of genetic and sweat chloride tests.
It is important to diagnose cystic fibrosis as young as possible to start treatment early. Newborn screening makes it possible to detect the disease early in life. Early treatment helps prevent complications and can improve survival.
All newborns in the United States are tested for cystic fibrosis. Newborn screening identifies more than half of cystic fibrosis cases. However, many people born before 2010 have not been screened.
Newborn screening for cystic fibrosis is performed during a baby’s first 2 to 3 days of life. A few drops of blood from a heel prick are placed on a special card and tested by a lab.
Every state and the District of Columbia begin screening with a blood test to check for levels of immunoreactive trypsinogen (IRT), a chemical made by the pancreas. In people who have cystic fibrosis, IRT tends to be high. However, most babies with high levels of IRT do not have cystic fibrosis. IRT can also be high for other reasons, such as if the baby was born preterm (premature), had a stressful birth, or is a carrier of cystic fibrosis.
Some states test only IRT for cystic fibrosis newborn screening. In other states, if IRT is high, then the hospital will test the baby’s DNA for some of the CFTR mutations that cause cystic fibrosis. After a positive screening test, diagnosis is confirmed with more tests.
Genetic testing may be used to look for carriers of mutated CFTR genes and to screen relatives of people who have cystic fibrosis. Genetic testing looks at your DNA from a blood or saliva sample or cells from the inside of your cheek.
Genetic testing can tell you whether you are a carrier of a mutated CFTR gene. This is called carrier screening. It is your choice whether to have this test. People who inherit a mutation of the CFTR gene from one parent are cystic fibrosis carriers. People who have inherited a mutation of the CFTR gene from both parents will have cystic fibrosis. Learn more about how cystic fibrosis is inherited.
The standard test to check for cystic fibrosis carriers looks for 23 or more of the most common disease-causing gene mutations. If your test did not identify a CFTR mutation, there is still a small chance that you could carry a type of mutation that did not show up on the test.
Siblings (brothers and sisters) of a person who has cystic fibrosis may want to be tested for cystic fibrosis even if they do not have symptoms. Other family members, such as first cousins and half-siblings, may be tested if they have symptoms or if the family is concerned that those individuals might have cystic fibrosis or be carriers.
After a positive or unclear screening test result, the diagnosis should be confirmed with further testing. A genetic counselor can help you understand the meaning of your carrier screening result.
Genetic tests done before or during pregnancy can look for a mutated CFTR gene. The tests use a sample of blood, saliva, or cells from the inside of your cheek to check your DNA. It is your choice whether to have this screening. Talk with your healthcare provider about screening if you’re thinking about getting pregnant or if you’re already pregnant.
Couples who are planning to have children may want to be tested to see whether they are cystic fibrosis carriers. Getting tested before pregnancy gives you more options and more time to make decisions if results show that one or both parents has a mutated CFTR gene.
Often the mother is tested first. If the father has a family history of cystic fibrosis, he may be tested first. If one parent is a carrier for a CFTR gene mutation, then the next step is to test the other parent.
If you are already pregnant, both parents may be tested at the same time. If you are both cystic fibrosis carriers, then prenatal diagnostic testing may be performed to check the unborn baby for mutated CFTR genes.
A sweat test checks for high levels of chloride in your sweat. The sweat test is the standard test for diagnosing cystic fibrosis. It may be used if you have symptoms that could indicate cystic fibrosis or to confirm a positive diagnosis from a screening of your newborn baby. A normal sweat chloride test result alone does not mean you do not have cystic fibrosis. Lower levels of chloride may indicate the need for further testing to diagnose or rule out cystic fibrosis.
The sweat test detects a higher amount of chloride — a component of salt — in the sweat of people who have cystic fibrosis. In order to produce sweat for this test, a colorless, odorless chemical and a little electrical stimulation are applied to a small area of a person’s arm or leg. The sweat is collected and sent to a hospital lab for testing.
Although there is not yet a cure for cystic fibrosis, advances in treatment are helping many people live longer, healthier lives. To manage the disease, you will work with a team of healthcare providers, including cystic fibrosis specialists. For newborns with a positive screening result, treatment may begin while the diagnosis is being confirmed.
Treatment for cystic fibrosis focuses on medicines and other ways to clear the airway. Other medicines can improve the function of the faulty CFTR protein and help prevent complications. Sometimes breathing support, nutritional support, or surgery is needed.
Your healthcare providers will likely include a cystic fibrosis specialist. This is a doctor who is familiar with the complex nature of cystic fibrosis.
Your cystic fibrosis care team may include:
Airway clearance techniques help loosen lung mucus so it can be cleared, reducing infections and improving breathing. The techniques may include special ways to breathe and cough, devices used by mouth, therapy vests that use vibrations to loosen mucus, and chest physical therapy. These techniques are often used along with medicines such as bronchodilators (medicines that open up the airways) and mucus thinners.
Medicines to treat cystic fibrosis may maintain and improve lung function, fight infections, clear mucus and help breathing, or try to improve how well someone’s CFTR protein works.
People who are Asian, Black, or Hispanic are more likely to have mutations that won’t respond to available CFTR modulators.
If you are not eligible for treatment with a CFTR modulator, your healthcare provider may recommend participating in a clinical trial. Scientists continue to work on new treatments for cystic fibrosis.
It can be very hard for people to find out that CFTR modulators won’t work for them because of the type of CFTR gene mutation they have. It is common to feel depressed or anxious if you learn that you are not eligible for CFTR modulators. Talk with your healthcare team about mental health support and other treatment options for you.
