Cystic fibrosis is an inherited disease caused by mutations in a gene called the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The CFTR gene provides instructions for the CFTR protein. The CFTR protein is located in every organ of the body that makes mucus, including the lungs, liver, pancreas, and intestines, as well as sweat glands. The CFTR protein has also been found in other cells in the body, such as cells of the heart and the immune system. The mutations in the CFTR gene cause the CFTR protein to not work properly. This causes thick, sticky mucus and blockages in the lungs and digestive system.
Normally, mucus coats tiny hair-like structures called cilia in the airways of your lungs, which sweep the mucus particles up to the nose and mouth where your body can get rid of them. In people who have cystic fibrosis, this process does not work properly. Learn more in our How the Lungs Work Health Topic.
There are almost 2,000 known disease-causing mutations of the CFTR gene. Different mutations have different effects on how the CFTR protein is made and how it works. In the most common gene mutation, part of the CFTR gene is missing, resulting in a protein that does not work properly.
Learn more about what the CFTR protein does in your body.
Normally, the CFTR protein controls the movement of ions from inside the cell to outside the cell. In people who have cystic fibrosis, the mutated gene causes the protein to not work properly, which, in turn, affects the movement of sodium and water. When this happens, the sweat glands make sweat that is saltier than it is in people who do not have cystic fibrosis. Also, there is less water in the mucus, which makes the mucus thick and sticky. The thick mucus creates blockages in the lungs and digestive system.
Every person inherits two CFTR genes, one gene from each parent. Children who inherit a CFTR gene with a mutation from both parents will have cystic fibrosis. When a mutated CFTR gene is inherited from only one parent and a normal CFTR gene is inherited from the other, the person will be a cystic fibrosis carrier. CF carriers are generally healthy, but they can pass the mutated CFTR gene on to their children.
The image below shows how two parents who are both CF carriers can pass a CFTR gene mutation on to their children.
A person may have an increased risk for cystic fibrosis because of his or her family history and genetics, and race or ethnicity.
A person is at higher risk for having cystic fibrosis if one or both parents is a carrier of a mutated CFTR gene or has cystic fibrosis. A person is also at higher risk if a sibling, half-sibling, or first cousin has cystic fibrosis. More than 10 million Americans are carriers of a CFTR gene mutation, yet many of them do not know it.
Cystic fibrosis is most common in people of northern European ancestry and less common in Hispanics and African Americans. It is relatively uncommon in Asian Americans.
Genetic testing may be performed to look for carriers, as well as to screen relatives of people who have cystic fibrosis. Genetic testing may also be used as prenatal screening tool to look for a mutated CFTR gene. All newborns in the United States are now screened for cystic fibrosis. Since universal screening for cystic fibrosis began relatively recently, there are still young people and adults who have not been screened.
Genetic testing can tell you if you carry a mutation of the CFTR gene. This is called carrier testing. People who have inherited 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 in Causes. Genetic testing looks at your DNA from a blood or saliva sample, or cells from the inside of your cheek.
The standard test to check for possible cystic fibrosis carriers looks for 23 of the most common disease-causing gene mutations. If you have a positive test, there is a 99 percent chance you are a carrier. However, if you have a negative test, there is still a small chance that you could carry a CFTR mutation that did not show up on the test.
Siblings of a person who has cystic fibrosis may want to be tested for cystic fibrosis whether or not they have symptoms. Other relatives, such as first cousins and half-siblings, may be tested if they have symptoms, or if the family is concerned that the individual may have cystic fibrosis.
After a positive screening test, the diagnosis should be confirmed with further testing.
Review who is more likely to be a CF carrier in Risk Factors.
Couples who are planning to have children may want to be tested to see if they are cystic fibrosis carriers. Genetic testing, such as the carrier screening described above, may be done before or during pregnancy. Often, the mother is tested first. However, if you are already pregnant, you and your partner may choose to be tested at the same time. If the father has a family history of cystic fibrosis, he may be tested first. Similar to standard genetic testing, prenatal screening uses a sample of blood, saliva, or cells from the inside of your cheek to check your DNA.
If one partner is a carrier for a cystic fibrosis gene mutation, then the next step is to test the partner if this has not been done. If both parents are cystic fibrosis carriers, then prenatal diagnostic testing may be performed to see whether your unborn baby has cystic fibrosis or is a carrier.
When a child has cystic fibrosis, it is very important to diagnose it early to help prevent complications. Newborn screening for cystic fibrosis is performed during a baby’s first two to three days of life. A few drops of blood from a heel prick are placed on a special card and analyzed in labs.
The type of newborn screening that is performed varies from state to state. Every state and the District of Columbia begins with a blood test to check for levels of a chemical made by the pancreas called immunoreactive trypsinogen (IRT). 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 may also be high if the baby is premature, had a stressful delivery, or is a carrier of cystic fibrosis.
Some states test only IRT for cystic fibrosis newborn screening. Other states test IRT and also perform DNA testing. In states that test both IRT and DNA, if IRT is high, then the hospital will test the baby’s DNA for some of the gene mutations that cause cystic fibrosis.
After a positive screening test, the diagnosis should be confirmed with further testing.
There is no way to prevent whether or not you have cystic fibrosis. Couples who are planning to have children and know that they are at risk of having a child with cystic fibrosis may want to meet with a genetic counselor. A genetic counselor can answer questions about the risk and explain the choices that are available.
Symptoms of cystic fibrosis depend on which organs are affected and the severity of the condition. Most patients who have cystic fibrosis have noticeable symptoms. Some patients have few or no signs or symptoms, while others experience severe symptoms or life-threatening complications. Symptoms may also change over time. The most common complications of cystic fibrosis affect the lungs and pancreas.
Cystic fibrosis most commonly affects the lungs. Some people who have cystic fibrosis may have wheezing and a cough that may produce mucus or blood.
Other signs and symptoms depend on the organs affected and may include:
Cystic fibrosis affects many parts and systems of the body. Complications will depend on the affected organs and the severity of disease. People who have cystic fibrosis produce thick, sticky mucus that causes problems in the lungs and digestive system. The buildup of mucus in the lungs makes it easy for bacteria to grow and often leads to serious lung infections. People who have cystic fibrosis often have problems with nutrition, too, because their pancreas does not work properly.
Possible complications of cystic fibrosis include:
To diagnose cystic fibrosis, your doctor may recommend some of the following tests and procedures:
How is a sweat chloride test performed?
The sweat test detects a higher amount of chloride—a component of salt that is made of sodium and chloride—in the sweat of people who have cystic fibrosis. In order to make sweat for this test, a colorless, odorless chemical and a little electrical stimulation are applied to a small area of an arm or leg. The sweat is collected and sent to a hospital lab for testing.
While there is not yet a cure for cystic fibrosis, advances in treatment are helping people live longer, healthier lives. To better manage your condition, you or your child will work with cystic fibrosis specialists. In newborns with a positive screening result, treatment may begin while the diagnosis is being confirmed. Treatment for cystic fibrosis is focused on airway clearance, medicines to improve the function of the faulty CFTR protein and prevent complications, and surgery, if needed.
Your healthcare team will likely include a cystic fibrosis specialist. This is a doctor who is familiar with the complex nature of cystic fibrosis. Your doctor may work with a medical team that specializes in cystic fibrosis, often at major medical centers. The United States has more than 100 CF Care Centers, with medical teams that include:
Airway clearance techniques help loosen lung mucus so it can be cleared, reducing infections and improving breathing. The techniques include special ways of breathing and coughing, devices used by mouth and therapy vests that use vibrations to loosen mucus, and chest physical therapy. These techniques are often used along with medicines such as bronchodilators and mucus thinners.
Medicines to treat cystic fibrosis include those used to maintain and improve lung function, fight infections, clear mucus and help breathing, and work on the faulty CFTR protein. Your doctor may prescribe some of the following medicines to treat cystic fibrosis:
If you or your child has been diagnosed with cystic fibrosis, it is important that you continue your treatments, follow up with your doctors, and learn how to manage the condition.
Regular checkups with your doctor may be part of your follow-up and treatment. How often your regular checkups take place will depend on your age. Younger patients, and those who have just been diagnosed, will have more frequent visits. As adults, you may see your doctor less often, perhaps every three months and then once a year for an evaluation.
Regular checkups may include:
Return to Treatment to review possible treatment options for your cystic fibrosis.
In addition to more frequent regular checkups, you may need to see your doctor for additional tests and evaluations, which may include the following:
Staying healthy is an extremely important part of cystic fibrosis care. Your medical team will work with you to develop a plan for lifestyle changes that can become part of your everyday life. These include the following:
To help you prevent complications and reduce the risk of infections, your doctor may recommend the following:
Your doctor may recommend medicines to treat complications of cystic fibrosis, including:
Cystic fibrosis may have serious complications. Call your doctor if you believe you have any of the following:
Return to Signs, Symptoms, and Complications to review complications.
Learn about the following ways in which the NHLBI continues to translate current research and science into improved health for people who have cystic fibrosis. Research on this topic is part of the NHLBI’s broader commitment to advancing lung disease scientific discovery.
Learn about exciting ways the NHLBI has contributed to advances in cystic fibrosis.
In support of our mission, we are committed to advancing cystic fibrosis research in part through the following ways:
Learn about exciting research areas the NHLBI is exploring that involve cystic fibrosis.
We lead or sponsor many studies on cystic fibrosis. See if you or someone you know is eligible to participate in our clinical trials.
To learn more about clinical trials at the NIH Clinical Center or to talk to someone about a study that might fit your needs, call the Office of Patient Recruitment 800-411-1222.
After reading our Cystic Fibrosis Health Topic, you may be interested in additional information found in the following resources.