Cystic fibrosis

Also known as mucoviscidosis

Cystic fibrosis (CF) is an inherited disorder which creates breathing and digestive problems by clogging organs in the body with a thick, sticky mucus.

Key points

  1. CF is the most common inherited disorder in New Zealand, and other Western countries including the UK and the USA.
  2. It affects the mucus and sweat glands causing mucus to be thick and sticky. This can build up in the lungs, intestine, liver and pancreas leading to breathing problems, repeated lung infections and digestive problems.
  3. The symptoms and severity of CF varies from mild to severe.
  4.  Some babies show signs of infection or poor weight gain from a young age. Other people have mild disease and it doesn't show up until they are in their teens or early adulthood.
  5. CF is a long-term condition which has a huge impact on a person’s life. However, with appropriate treatment, care and support, most people with CF still manage to live a normal life.

Causes

Cystic fibrosis is caused by a problem or mutation in one of our genes. 

  • We now know that the specific mutation for CF is found on chromosome 7 and is known as "transmembrane conductance regulator (CFTR) gene."
  • There are multiple problems that can occur; so far at least 1,500 mutations in the CFTR gene have been found.
  • These different mutations help explain why some people have milder disease while others have more severe disease.

Read more: Genetics of cystic fibrosis – a layperson’s guide Cystic Fibrosis Association of NZ

Who is at risk?

The only risk factor for CF is a family history of the condition. To get CF, a child needs to inherit two faulty genes: one from their mother and one from their father. 

If both parents carry the CFTR gene, with each pregnancy there is a:

  • 1 in 4 chance that the child will have CF
  • 2 in 4 chance that the child will be a carrier of the CF gene
  • 1 in 4 chance that the child will not have CF and will not be a carrier. 

CF affects 1 in 2,500 newborns. Among different ethnic groups:

  • CF is the most common inherited disease in European or Caucasian populations.
  • CF is less common in African, Maori and Pacific populations.
  • One in 25 European or Caucasian people carry one copy of the gene from one of their parents. Most of these people have no symptoms and may not even know they are a 'carrier'.

Symptoms

Symptoms of cystic fibrosis vary and depend upon the age and disease severity.

In babies, symptoms can include:

  • delayed growth or failure to gain weight normally
  • no bowel movements in first 24 to 48 hours of life
  • salty-tasting skin.

In children and adults symptoms may include:

  • weight loss or poor weight gain or growth
  • severe constipation and abdominal pain
  • nausea and loss of appetite
  • increased gas, bloating, or a belly that appears swollen (distended)
  • stools that are pale or clay coloured, foul smelling, have mucus, or that float
  • belly pain from severe constipation
  • infertility (in men)
  • fatigue
  • coughing and increased mucus in the chest
  • recurrent chest infections or pneumonia
  • sinus pain and infections (50% of people with CF have nasal polyps).

Complications

Complications from cystic fibrosis often affect the lung or digestive system. Patients can develop a condition called bronchiectasis where the airways are abnormally large and chest infections are common. Having CF for a number of years can also affect the heart.

Other complications include:

  • nasal polyps which affects 50% of people with CF
  • pancreatic insufficiency which affects 85% of people with CF, who then require pancreatic replacement enzymes
  • liver disease usually affects up to 30% of people with CF by adulthood
  • CF-related diabetes is usually present in 2% of children, 19% of adolescents and 40-50% of adults with CF
  • progressive respiratory failure.

Diagnosis 

The diagnosis of cystic fibrosis can be made through a range of tests. 

Guthrie heel prick

Most babies with CF are diagnosed through a screening test done shortly after birth. This test, called the Guthrie heel prick, checks for a range of genetic disorders. If a heel prick test is abnormal, further testing is done to check if this is CF or not.

Sweat test

The sweat test is another way of making a diagnosis of cystic fibrosis. Here, an abnormally high level of salt is found in a child or adult's sweat.

Chorionic villus sampling

In women who are pregnant, a special test known as chorionic villus sampling may be performed. A small amount of fluid is removed from the womb and is analysed for the presence of the CFTR gene.

Genetic testing

Genetic testing through a blood test can also be offered to family members, potential partners or to help detect carriers of the CFTR gene.

X-ray and sputum analysis

Patients who develop chest infections may require an x-ray and analysis of the sputum to detect the presence of any bacteria.

Treatment

Cystic fibrosis is a long-term condition for which there is currently no cure. However, research into this is ongoing and treatment for CF have improved greatly over the past few years.

The goals of CF treatment include:

  • preventing and controlling lung infections
  • clearing the thick, sticky mucus from the lungs
  • reducing inflammation and improving lung function
  • preventing or treating blockages in the intestines
  • ensuring enough nutrition and preventing dehydration (a lack of fluid in the body).

Treatment options for CF include:

  • antibiotics
  • inhaled enzymes (called Pulmozyme)
  • insulin to manage diabetes
  • inhalers to open up the airways
  • steroids to help reduce swelling within the airways
  • physiotherapy and postural drainage of the chest.
  • diet tailored to your needs – often a special diet that is high protein and calories is needed
  • pancreatic enzymes to help absorb fats and protein
  • vitamin supplements, especially vitamins A, D, E, and K
  • nasal steroids for, or surgical removal of, nasal polyps. 

Treatment can be complex and is best is coordinated by a specialist team working alongside the patient, their family and their doctor.

Prevention

Unfortunately, cystic fibrosis cannot be prevented. If the parents are both carriers of the gene, then there is a 1 in 4 chance that the child may get the condition. However, steps can be taken to ensure that the child leads a healthy and normal life. This can include:

    • chest physiotherapy and postural drainage of the lungs
    • constant cycles of antibiotics to help prevent infections from occurring
    • immunisations to help reduce the chance of developing new infections
    • maintaining good nutrition and an ideal body weight to help fight off infections. 

Learn more

About cystic fibrosis Cystic Fibrosis Association (NZ)
Genetics of cystic fibrosis – a layperson’s guide Cystic Fibrosis Association of NZ
Cystic fibrosis NHS Choices (UK)
Cystic fibrosis Patient Info, UK
Resources on cystic fibrosis Medline Plus (USA)

Credits: Health Navigator Team.