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Cystic Fibrosis

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What is Cystic Fibrosis?

What is Cystic Fibrosis?

Cystic fibrosis is a hereditary disorder that causes the overproduction and thickening of mucus and digestive juices, which can clog the pathways, tubes, and ducts throughout the body and increase salt concentration in sweat. These fluids are normally thin and slippery. However, people with cystic fibrosis have inherited a defective gene that produces thick, sticky body fluids. These fluids no longer serve as lubrication, but rather clog up the tubes, ducts, and pathways, particularly in the lungs and pancreas.

Significant medical advances have developed over the past decades that greatly improve a person’s quality of life and longevity.

Types of CFTR Mutations in Cystic Fibrosis

Types

CFTR stands for cystic fibrosis transmembrane conductance regulator. This is a protein that acts as a chloride channel and is necessary for balancing the salt and water on surfaces in the body, such as the lungs. If this protein is not functioning properly, chloride, an element of salt, is trapped within the cells. If the chloride is not eliminated from the cell, water cannot hydrate the cell’s surface; this causes thick, sticky mucus to form which can block necessary passages.

CFTR gene mutations cause the CFTR protein to malfunction. In some cases, the protein is not produced at all. This malfunction or lack of CFTR protein is present in cystic fibrosis. People with this condition experience frequent lung disease, pancreatic damage, and complications to other vital organs like the liver.

CFTR mutations are divided into six classes:

  • Protein production (Class I). In people with cystic fibrosis, the CFTR gene either does not work well or at all, causing insufficient quantities of CFTR protein to be produced. If this problem occurs, insufficient water is available to cover the cell, and the mucus in the airways becomes dehydrated, thick, and sticky. It eventually adheres to the cilia, flattening it and disrupting its ability to move the mucus. W1282X is an example of this mutation.
  • Protein processing mutations (Class II). This mutation removes a single amino acid from the CFTR protein. Without this amino acid, the CFTR protein cannot keep its correct 3D form. The cell cannot recognize the misshapen protein and eliminates it. An example of this defective protein maturation and premature degradation is F508del, the most common cystic fibrosis mutation in the United States.
  • Gating mutations (Class III). The CFTR protein is shaped like a tunnel with a gate. The cell opens the gate when chloride needs to pass through; if not, the gate stays closed. Gating mutations keep the gate locked, not allowing chloride to pass through. An example is the G551D mutation.
  • Conduction mutations (Class IV). A change in one amino acid of CFTR could produce a 3D-shaped protein, but one that doesn’t function properly. R117H is an example of this class. Chloride must flow freely through the protein’s channels. If the mutation causes a change in the channel’s shape, the chloride cannot move through the pathway.
  • Insufficient protein mutations (Class V). This type of mutation causes insufficient normal CFTR protein at the cell’s surface, such as the 5T variant. This might occur because there is a lack of CFTR protein being produced or because only limited amounts of CFTR protein on the cell’s surface are working properly. It may also occur if there are normal amounts of the CFTR protein, but they dissipate quickly, leaving an inadequate number of proteins behind.
  • Reduced Stability of CFTR (Class VI). This class causes reduced stability of CFTR and accelerated turnover from the cell surface. An example of this variant is 4326delTC.

Signs & Symptoms of Cystic Fibrosis

Symptoms

The signs and symptoms of cystic fibrosis will vary according to the severity of a person’s condition. A person’s initial symptoms could worsen or improve with time. Some individuals do not experience symptoms until they are teenagers or adults. Typically, people diagnosed with cystic fibrosis later in life have a much milder form. Latent symptoms for cystic fibrosis include pancreatitis (inflamed pancreas), frequent pneumonia, or infertility.

Other symptoms of cystic fibrosis are increased salt in a person’s sweat, which can cause electrolyte abnormalities during hot summer days, respiratory and lung problems, and digestive issues. Eight of 10 individuals with cystic fibrosis suffer from malabsorption of fat and protein and can present as a failure to thrive.

Respiratory symptoms

Cystic fibrosis is marked by the production of thick, sticky mucus that clogs the airways to the lungs. This overproduction of thick mucus can be noticed as:

  • A lasting cough with thick mucus
  • Frequent lung infections
  • Inflamed nasal passages or repeated sinusitis
  • Crackles and chest congestion
  • Intolerance of physical activity
Digestive symptoms

Thick mucus clogs the pathways that transport digestive enzymes from the pancreas to the small intestine. These enzymes are essential for the body to extract nutrients from the food we eat. Symptoms of cystic fibrosis affecting the digestive system include:

  • Fatty stools (poop) – foul-smelling, greasy stools
  • Low growth and weight gain
  • Intestinal blockage is common in infants. A condition called meconium ileus can occur in 15% of individuals with cystic fibrosis; thick mucus clogs the intestinal tract with meconium—the first bowel movement for an infant.
  • Rectal prolapse can happen because of chronic constipation and straining to poop; part of the rectum bulges from the anus.

Cystic fibrosis is a hereditary disease. Speak with your child’s pediatrician if you’re concerned this disease may run in your family. It may be recommended that you speak with a genetic specialist before starting a family. If your child shows symptoms of cystic fibrosis, seek immediate medical attention; coughing up blood, difficulty breathing, and extreme intestinal pain are possible signs of cystic fibrosis.

Cystic fibrosis is a lifelong condition that requires regularly scheduled visits to the cystic fibrosis care center every few months. Call your doctor or pediatrician if your child’s symptoms worsen such as an increase in mucus, significant weight loss, or persistent constipation.

More to explore

What Causes Cystic Fibrosis?

Causes

Cystic fibrosis is an inherited disease caused by a gene—the cystic fibrosis transmembrane conductance regulator gene (CFTR).

Cystic fibrosis requires two copies of the mutated gene—one from each parent—to cause the disease to develop in a person. If only one copy of this mutated gene is inherited, the person will not acquire cystic fibrosis. However, they are carriers of cystic fibrosis and may pass the mutated gene to their children.

Risk Factors

Risk Factors

Because cystic fibrosis is an inherited disease, a person must receive two defective recessive genes from each parent. If both parents are carriers of the defective gene, with each pregnancy, there is a one in four—or 25%—chance of having a child with cystic fibrosis.

If a person knows they are a carrier of the gene (CFTR), it is highly recommended they seek genetic counseling from an expert at an accredited cystic fibrosis center before getting pregnant. Though being a carrier does not affect their health, they can pass the defective gene to their children.

Prevention

Prevention

Understanding that cystic fibrosis is an inherited disease indicates that genetic counseling and genetic testing should be considered before starting a family. Genetic testing examines your DNA from either a blood or saliva sample or a swab from inside your cheek. Various tests exist in the market that can detect different numbers of the most common gene mutations that cause diseases or can sequence the CFTR protein with deletion and duplication analysis.

Complications

Complications

Cystic fibrosis is a serious illness that affects multiple parts of the body; it can carry many complications. Cystic fibrosis predominantly affects the respiratory, digestive, and reproductive systems. Other organs can also be affected.

Respiratory
  • Bronchiectasis. Cystic fibrosis commonly causes abnormal widening and bronchial tubes (airways) scarring. It makes breathing and clearing the lungs of mucus difficult. This is a chronic lung condition.
  • Chronic lung infections. Bacteria can easily grow in the thick mucus that is produced by cystic fibrosis; therefore, people with this condition frequently have sinus infections, bronchitis, and pneumonia. Antibiotic-resistant bacteria poses a problem when treating these infections.
  • Nasal polyps. Since the lining of the nose is frequently inflamed because of infections, fleshy growths called polyps can grow inside the nose.
  • Hemoptysis. This term is a symptom of chronic infection and inflammation. If this infection is located near a blood vessel in the lung, coughing up blood is a symptom. Only small amounts of blood are spewed; however, if blood amount increases, it could become more serious.
  • Pneumothorax. If air gets between a lung and the chest wall, the lung could collapse. This is more common is adults with cystic fibrosis. Chest pain and difficulty breathing are signs of this condition. People have described the feeling as a bubbling sensation.
  • Respiratory failure. Cystic fibrosis continues to damage delicate lung tissue. Eventually, the lung may lose its elasticity and no longer function. This could become fatal; respiratory failure is the number one cause of death among people with cystic fibrosis.
  • Acute exacerbations. As cystic fibrosis continues to damage the lungs and the respiratory system with mucus, increased coughing and shortness of breath can create acute exacerbation. Antibiotics are the usual treatment for this condition. Hospitalization is a strong possibility if this occurs, though home treatment could be an option. Weight loss and extreme fatigue are symptoms of acute exacerbation.
Digestive system
  • Malnutrition. Thick mucus blocks the digestive tubes to and from the pancreas to the intestines. This blockage causes the depletion of the enzymes necessary to extract nutrients from proteins and fats, including fat-soluble vitamins. This lack of nutrients leads to poor growth, weight loss, and failure to thrive.
  • Diabetes. Insulin, which is produced in the pancreas, metabolizes sugar so the body receives energy. Over time, pancreas complications from cystic fibrosis increase the risk of developing diabetes. It is estimated that about 20% of teenagers with cystic fibrosis also have diabetes; this number increases to as much as 40-50% of people reaching adulthood.
  • Liver disease. Thick mucus causes inflammation and blockage to the pathways used to transport bile from the liver and gallbladder to the small intestine. Liver and gallbladder conditions such as cirrhosis, fatty liver disease, jaundice, and gallstones can occur.
  • Intestinal blockage. Cystic fibrosis can cause a condition called meconium ileus in neonates or distal intestinal obstruction syndrome (DIOS) in older children and adults.
  • Distal intestinal obstruction syndrome (DIOS). This serious condition causes the bowel to become partially or totally blocked, usually by the small intestine joining the large intestine.
Reproductive system complications
  • Infertility in men. Many men with cystic fibrosis are infertile because the tube that carries the sperm from the testes and the prostate gland is blocked or missing. The sperm is normal, and in vitro fertilization allows men to become biological fathers.
  • Infertility in women. Though infertility or difficulty getting pregnant is a symptom of cystic fibrosis, women can become pregnant. However, symptoms of cystic fibrosis may worsen during pregnancy. Discussing the risks of pregnancy with your cystic fibrosis doctor is recommended.
Other complications
  • Osteoporosis. Cystic fibrosis increases a person’s risk of developing osteoporosis—bone thinning. Arthritis or joint and muscle pain are common in this condition.
  • Electrolyte imbalances and dehydration. People with cystic fibrosis have difficulty hydrating their cells because of the higher content of chloride, a component of salt, in sweat. This increase in salt makes a person with cystic fibrosis have saltier sweat. In addition, dehydration is common, especially during exercise, physical activity, or in hot weather. Signs of dehydration include fatigue, low blood pressure, increased heart rate, and feeling faint.
  • Mental health complications. People with cystic fibrosis often experience depression and feelings of anxiety. Having an incurable, debilitating disease are understandable causes for these feelings.
Get Care

Trust NewYork-Presbyterian for Birth Defect Care

NewYork-Presbyterian offers exceptional care for patients with cystic fibrosis. The Sue and John L. Weinberg Cystic Fibrosis Center at NewYork-Presbyterian/Morgan Stanley Children’s Hospital is a New York State-approved referral center for newborn cystic fibrosis screenings. Additionally, NewYork-Presbyterian is accredited by the Cystic Fibrosis Foundation.

Know the signs and symptoms of cystic fibrosis. Let our team of world-renowned doctors and surgeons help alleviate some of the difficulties that come with this disease. NewYork- Presbyterian has the means to help keep you and your child amazing.