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, tissues, and the glands that make mucus and sweat.
Mucus is normally slippery and protects the linings of the airways, digestive tract, and other organs and tissues. People who have cystic fibrosis make thick, sticky mucus that can build up and lead to blockages, damage, or infections in the affected organs. Inflammation also causes damage to organs such as the lungs and pancreas.
Some people who have cystic fibrosis have few or no signs or symptoms, while others experience severe symptoms or life-threatening complications. Symptoms of cystic fibrosis depend on which organs are affected and the severity of the condition. The most serious and common complications of cystic fibrosis are problems with the lungs, also known as pulmonary or respiratory problems, which may include serious lung infections. People who have cystic fibrosis often also have problems maintaining good nutrition, because they have a hard time absorbing the nutrients from food. This is a problem that can delay growth.
Your doctor may recommend treatments to improve lung function and manage other complications. Early treatment can improve your quality of life and help you live longer.
Causes- Cystic Fibrosis
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.
What gene mutations cause cystic fibrosis?
- Cystic Fibrosis
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.
Risk Factors- Cystic Fibrosis
A person may have an increased risk for cystic fibrosis because of his or her family history and genetics, and race or ethnicity.
- Family history
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.
- Race and ethnicity
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.
Screening and Prevention- Cystic Fibrosis
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.
- Carrier Selection To Detect CFTR Mutations For Cystic Fibrosis
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.
- Prenatal Screening For Cystic Fibrosis
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.
- New Born Screening
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.
- Prevention Of Cystic Fibrosis
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.
Signs, Symptoms, and Complications- Cystic Fibrosis
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.
- Signs and Symptoms Of Cystic Fibrosis
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:
- Blockage of the intestine in a baby soon after birth
- Clubbing of fingers and toes due to less oxygen getting to the hands and feet
- Fever, which may include night sweats
- Gastrointestinal symptoms, such as severe abdominal pain, chronic diarrhea, or constipation
- Jaundice, or yellow skin, for an abnormally long time after birth
- Low body mass index (BMI) or being underweight
- Muscle and joint pain
- Delayed growth or puberty
- Salty skin and saltier than normal sweat
- Sinus infections
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:
- Allergic bronchopulmonary aspergillosis (ABPA), which is an allergic reaction in the lungs to the fungus Aspergillus.
- Bronchiectasis, a widening of the airways in the lungs caused by chronic inflammation or obstruction of the airways. This is a common complication of cystic fibrosis.
- Cancers of the digestive tract, including the esophagus, stomach, small bowel, large bowel, liver, and pancreas
- Collapsed lung, called pneumothorax, resulting in air in the space between your lung and chest wall
- Diabetes due to damage to the pancreas. The pancreas is where insulin is made.
- Fertility problems
- Gastrointestinal complications, such as distal intestinal obstruction syndrome (DIOS), in which your intestine becomes blocked by very thick intestinal contents. Another possible complication is rectal prolapse, in which part of the rectum sticks out through the anus.
- Heart failure because of lung damage
- Kidney problems due to diabetes and some antibiotics, or kidney stones
- Liver disease or failure caused by blockage of the bile ducts in the liver, which leads to bile damaging your liver. This may lead to cirrhosis and a need for a liver transplant.
- Lung infections that may come back or be difficult to treat
- Malnutrition because the pancreas may not make enough enzymes to help digest and absorb nutrients from food
- Mental health problems, such as depression and anxiety
- Muscle and bone complications, including low bone density and osteoporosis, joint pain and arthritis, and muscle pains
- Pancreatitis and low levels of pancreatic enzymes leading to nutritional deficiencies, including low levels of vitamins A, D, E, and K
- Pulmonary exacerbations, which are episodes of worsening cough, shortness of breath, and mucus production caused by airway inflammation and blockage from an increase in bacteria in your airways and lungs. These episodes may also cause fatigue, loss of appetite, and weight loss.
- Salt loss syndrome, in which your body quickly loses salt, or sodium and chloride, causing electrolyte and other imbalances.
- Urinary incontinence, or loss of bladder control
Diagnosis- Cystic Fibrosis
Your doctor may diagnose cystic fibrosis based on your signs and symptoms and results from certain tests, such as genetic and sweat tests that are done to confirm screening tests.
- Cystic Fibrosis
To diagnose cystic fibrosis, your doctor may recommend some of the following tests and procedures:
- Genetic testing to detect mutated CFTR genes. This test can confirm a positive cystic fibrosis screening test and sweat test. If genetic testing is done as part of newborn or other screening, it may not be repeated during the newborn stage. Genetic testing is described in more detail in Screening and Prevention.
- Prenatal diagnostic tests to diagnose cystic fibrosis in an unborn baby, using mutated CFTR genes. This is done with procedures that take either a sample of amniotic fluid, the liquid in the sac surrounding your unborn baby, or tissue from the placenta. Cells from these samples are checked for gene mutations. Infants with positive prenatal testing for cystic fibrosis will be further tested after birth to confirm the diagnosis of cystic fibrosis.
- Sweat test for high sweat chloride to see if you have 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 may indicate cystic fibrosis, or to confirm a positive diagnosis from a screening of your newborn baby. A normal sweat chloride test 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.
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.
Treatment- Cystic Fibrosis
While there is not yet a cure for cystic fibrosis, advances in treatment are helping people live longer, healthier lives. After early diagnosis, the goal is proactive treatment to slow down lung disease as much as possible. 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 prevent and fight infections, and surgery, if needed.
- Healthcare Cystic Fibrosis
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:
- Doctors specializing in the lungs, diabetes, and the digestive system
- Genetic counselors
- Nutritionists and dietitians
- Physical therapists
- Respiratory therapists
- Social workers
- Airway clearance techniques For Cystic Fibrosis
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 for Cystic Fibrosis
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:
- Antibiotics to prevent or treat lung infections and improve lung function. Your doctor may prescribe oral, inhaled, or intravenous (IV) antibiotics.
- Anti-inflammatory medicines, such as ibuprofen or corticosteroids, to reduce inflammation. Inflammation causes many of the changes in cystic fibrosis, such as lung disease. Ibuprofen is especially beneficial for children, but side effects can include kidney and stomach problems. Corticosteroids can cause bone thinning and increased blood sugar and blood pressure.
- Bronchodilators to relax and open airways. These treatments are taken by inhaling them.
- Mucus thinners to make it easier to clear the mucus from your airways. These treatments are taken by inhaling them.
- CFTR modulators that help improve the function of the faulty CFTR protein. They improve lung function and help with weight gain. Examples include ivacaftor and lumacaftor.
Surgery may be an option for people with advanced conditions. See Living With for more information.
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. The goal of cystic fibrosis care is to control symptoms and prevent complications.
- Cystic Fibrosis
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:
- Education about airway clearance, infection control, energy, and nutrition goals
- Height and weight measurement, and calculation of BMI
- Physical activity guidance
- Physical exam, including examination of the heart, lungs, and abdomen to check the liver and for abdominal pain
- Physical therapy evaluation and needsBlockage of the intestine
- Psychological assessment and support
- Monitor Health Condition
In addition to more frequent regular checkups, you may need to see your doctor for additional tests and evaluations, which may include the following:
- Abdominal ultrasoundexternal link or CT scan to look for the cause of abdominal pain, check the pancreas and liver, and look for distal intestinal obstruction.
- Blood tests to check for diabetes, infection, liver disease, side effects of medicines such as damage to kidneys, nutritional status including complete blood count, and vitamin levels.
- Bone mineral density tests to check for osteopenia or osteoporosis in those who are at risk. You may be at risk if you are take corticosteroids long term, have severe lung disease, or do not get adequate nutrition. Testing of bone mineral density may be done with an X-ray test called a dual-energy X-ray absorptiometry (DEXA or DXA) scans.
- Chest CT scan to look for changes in lung function or lung infection
- Chest X-ray to look for lung abnormalities and infections. Early changes may be seen on X-ray before you notice symptoms. In younger children this may be done every other year to decrease radiation exposure.
- Colonoscopy to monitor for colorectal cancer because of increased risk.
- Glucose monitoring and testing to check for cystic fibrosis-related diabetes.
- Lung biopsyexternal link to test for specific bacteria.
- Pancreas function testing, which may include looking at an enzyme called pancreatic elastase-1 in your stool.Blockage of the intestine
- Pulmonary function tests, which includes checking oxygen levels in your blood and spirometry, which is the most important and widely used tool to assess lung function in cystic fibrosis. Regular spirometry is used to monitor lung function in people age 6 and older and may be done in children as young as age 3.
- Respiratory sample smear and culture, which involves taking airway secretion or mucus samples every three months to look for microorganisms in the respiratory tract, and if necessary, treat them.
- Review of caloric intake, and pancreatic enzyme replacement.
- Review of treatments and medicines, including a pharmacist’s assessment.
- Prevent Complications
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:
- Avoiding tobacco smoke, including secondhand smoke.
- Being physically active to improve lung function. Physical activity helps with airway clearance and improves bone mineral density, muscle strength, flexibility, and posture. Before starting any exercise program, ask your doctor about what level of physical activity is right for you.
- Healthy eating to improve overall health. Healthy eating is also important for normal growth in children who have cystic fibrosis. You may need to increase your food or calorie intake by eating more foods or by eating high-energy foods. A high-sodium eating plan or supplementation with sodium may be recommended at times.
- Treatment of Complications
Your doctor may recommend medicines to treat complications of cystic fibrosis, including:
- Antibiotics to prevent or treat lung infections and pulmonary exacerbations.
- Insulin to treat diabetes caused by destruction of the pancreas, if needed.
- Medicine to help unclog ducts in the liver and improve bile flow. This includes ursodeoxycholic acid. This may improve abnormal liver function blood tests.
- Nutritional supplements when healthy eating is not enough. Your doctor may recommend supplements such as calcium, multivitamins, oral pancreatic enzymes, sodium, or vitamin A, D, E, and K.
- Oxygen therapy to treat low levels of oxygen in the blood. This may improve the ability to be physically active and attend school or work.
- Surgeries such as lung transplant may help people with advanced lung disease and respiratory failure. Liver transplant may be an option for advanced liver disease such as cirrhosis. A person who undergoes a lung transplant will also need pulmonary rehabilitation after the surgery.
- Learn Warning Signs Of Cystic Fibrosis
Cystic fibrosis may have serious complications. Call your doctor if you believe you have any of the following:
- Pulmonary exacerbation, which involves a worsening of lung symptoms, such as more coughing or wheezing, chest congestion, and a change in mucus color. You may also have weight loss, a poor appetite, or fever.
- Hemoptysis, which may be a sign that an artery has broken and is bleeding into the airway.
- Sudden shortness of breath or chest pain, which may be a sign of a pneumothorax, or collapsed lung.
Return to Signs, Symptoms, and Complications to review complications.
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