What is Cystic Fibrosis?

Cystic Fibrosis (CF) is an inherited condition characterized by the production of abnormally thick, sticky mucus, particularly in the lungs and digestive system. It is caused by having at least two harmful genetic changes in the CFTR gene. Normally, the job of mucus is to protect and lubricate different organs. However, the thickened mucus produced by individuals with CF blocks and clogs various systems in the body. Individuals with CF can have a variety of symptoms ranging from mild to severe.

The severity of CF symptoms can generally be predicted by the specific genetic changes in the CFTR gene that an individual inherits, although the symptoms may vary somewhat from person to person (even among those with the same genetic changes). There are certain CFTR genetic changes that are associated with a broad spectrum of disease, which means that the symptom severity can vary significantly between individuals with the same genetic changes and is difficult to predict. Some individuals with these particular genetic changes have severe CF, while others might have mild CF, a CFTR-related disorder (CFTR-RD), or even no symptoms at all.

Cystic Fibrosis

CF is usually diagnosed in infancy or early childhood. Severe forms of CF will typically involve multiple body parts including the lungs, pancreas, liver, and reproductive organs. Most individuals with CF experience breathing problems and frequent lung infections that lead to permanent lung damage such as scarring (fibrosis) and sac-like growths (cysts). The pancreas, an organ that produces important substances that help regulate blood sugar (insulin) and break down food (digestive enzymes), is often affected in individuals with severe CF. This prevents the body from digesting food properly resulting in diarrhea, malnutrition, and poor growth. Individuals with CF may develop CF-related diabetes as they age. Delayed puberty is also common among people with CF. Most men with the disorder have infertility due to congenital absence of the vas deferens (CAVD), a condition in which the vas deferens (a reproductive organ involved in sperm transport) fails to develop properly.

CFTR-related Disorders

A few individuals with two harmful genetic changes in the CFTR gene have some health problems associated with CF, but are not formally diagnosed with the condition. These individuals are considered to have a CFTR-related disorder, which can include symptoms affecting only one body part (such as only the lungs or only the pancreas). Men may have CAVD causing infertility as the only symptom.

Additional Considerations For Carriers

Most carriers do not experience any symptoms of CF. Rarely, carriers have symptoms of a CFTR-related disorder.

How common is Cystic Fibrosis?

The incidence of CF in the population is 1 in 3,000 births. The incidence of CF is more common among individuals of Northern European or Ashkenazi Jewish descent.

How is Cystic Fibrosis treated?

FDA approved medications are available for individuals with certain genetic changes in the CFTR gene. There are also many other options for treating the symptoms in everyone with CF, regardless of the genetic changes that are present. Because thick mucus can build up in the respiratory system, it is important to keep the patient's airways open to ease breathing and prevent infection. This can be accomplished with various prescription drugs as well as by physically loosening mucus by pounding on the patient's back in a specific way. This treatment, known as "postural drainage and chest percussion," can be performed by the affected person using a special vest or by someone other than the affected person, and is typically done at least once daily. As respiratory infections occur, doctors typically prescribe antibiotics.

Healthcare providers will also monitor the digestive system to ensure that the patient is getting proper nutrition. Medications such as enzymes or vitamin supplements may be prescribed. Both the respiratory and digestive systems of an individual with CF must be monitored regularly by a medical team.

Some men with CAVD may be able to have children with the use of assisted reproductive technologies.

Surgery may be needed to correct certain problems caused by CF, and lung transplant is an option for some individuals.

What is the prognosis for an individual with Cystic Fibrosis?

Individuals with CF have shortened lifespans. However, thanks to improved treatments and a better understanding of the condition, average life expectancy has been increasing over time. Many children who are born with CF today and receive proper treatment are expected to live into their fifties or sixties.

Other names for
cystic fibrosis

  • CFTR-related disorders
  • Fibrocystic disease of pancreas
  • Mucoviscidosis


  • Castellani et al., 2018, J Cyst Fibros., 17(2):153-178, PMID: 29506920
  • Chen et al., 2021, Animal Model Exp., 4(3):220-232, PMID: 34557648
  • Cystic Fibrosis Foundation Patient Registry, 2021, https://www.cff.org/media/23476/download
  • OMIM: Online Mendelian Inheritance in Man, OMIM [219700], 2022, http://www.omim.org/219700
  • Polgreen et al., 2022, Annu Rev Med., 73:563-574, PMID: 35084992
  • Savant et al., 2023, https://www.ncbi.nlm.nih.gov/books/NBK1250/
  • Sosnay et al., 2017, J Pediatr, 181S:S27-S32.e1, PMID: 28129809