What is Cystic Fibrosis?
Cystic Fibrosis (CF) is the most common serious genetic condition in Australia, affecting one in every 2500 babies. Boys and girls are affected equally.
In people with CF, the mucus secretions produced by various glands in the body are thicker and stickier than normal. In the airways and lungs, the thick mucus can cause repeated chest infections, leading to lung damage. In the digestive system, the thickened secretions can cause problems with digestion and nutrition.
While there is currently no cure for cystic fibrosis, improvements in treatment mean that people with this condition have a much longer life expectancy than in recent decades. People with cystic fibrosis may now live into their 40s and beyond, and life expectancy is improving all the time as new treatments emerge.
What are the symptoms of cystic fibrosis?
Common symptoms of cystic fibrosis include:
- A persistent wet cough - cough that produces sputum (mucus or phlegm).
- Shortness of breath or wheezing, especially when exercising.
- Frequent chest and sinus infections.
- Poor weight gain in infancy or childhood despite a good appetite. This happens because the thickened mucus can stop the release of enzymes from the pancreas that are needed to digest food.
- Frequent bowel motions, which may be loose or oily.
- Sweat that is saltier than usual - parents often notice the salty taste when they kiss their children. People with CF lose extra salt when they sweat, so in hot weather they may feel weak or tired and be prone to dehydration or heat stroke.
Not everyone with CF has the same symptoms. The severity of cystic fibrosis and the age that symptoms develop varies from person to person.
Conditions and complications associated with CF
People with cystic fibrosis may develop the following health problems:
- chronic (ongoing) or recurrent bronchitis;
- chronic or recurring sinusitis;
- problems with fertility (which affect men more than women);
- liver disease (which affects about one-third of people with CF and can eventually result in cirrhosis of the liver);
- bowel problems including constipation, diarrhoea, bloating, abdominal pain and bowel obstruction; and
- pancreatitis (inflammation of the pancreas).
Babies with CF may develop a bowel obstruction (meconium ileus) in the first few days of life.
Why do people with CF have thick mucus?
People with cystic fibrosis have a gene mutation. This mutation affects the structure and function of a protein that’s found in cells that line the lungs, gut, pancreatic ducts, sweat glands, and reproductive (sex) organs.
The affected protein - called the cystic fibrosis transmembrane conductance regulator (CFTR) - normally controls the movement of salts and water across membranes. In people with CF it doesn’t work properly. This results in mucus in the body becoming thick and sticky because it doesn’t have the right balance of salt and fluid.
How do you get cystic fibrosis?
Cystic fibrosis is an inherited condition. To have cystic fibrosis, you need to have 2 genes for the disease (one from each parent).
It is much more common to have just one CF gene — one in 25 people carries a CF gene. These people, known as carriers, do not have the disease or any symptoms.
If 2 CF carriers have children, with each pregnancy there is a one in 4 chance they will have a child with CF; a 2 in 4 chance the child will be a carrier; and a one in 4 chance the child will neither have CF nor be a carrier.
Cystic fibrosis is more common among Caucasian Australians of Northern European ancestry.
Testing for CF before or during pregnancy
Testing for a cystic fibrosis gene before or during pregnancy may be recommended for some people who may be at increased risk of being CF carriers. Testing may be recommended if you have a family history of cystic fibrosis or have a relative who is a known carrier of CF or have Northern European or Ashkenazi Jewish ancestry.
If testing is recommended, your doctor will refer you to a genetic counsellor.
Genetic carrier testing
Genetic carrier testing is available for cystic fibrosis. It involves testing a sample of saliva or blood to see if you carry the gene for cystic fibrosis. This test may be offered to women who are pregnant, or trying to become pregnant, and their partners.
Carrier testing is complex, as more than 2000 different gene abnormalities (variants) can lead to cystic fibrosis. Most laboratory tests only look for the 40 most common abnormalities, which are responsible for about 90 per cent of CF cases in Australia.
There are tests that can be done in pregnancy to determine if your baby will have CF. These tests are usually performed only if there is a family history of CF, or if carrier tests show that your baby may be at risk.
How is cystic fibrosis diagnosed?
Early detection of CF leads to improved outcomes. In Australia, screening for cystic fibrosis is recommended for all newborn babies.
Newborn screening test
The newborn screening test involves taking a tiny blood sample (heel prick blood spot test). It tests for several conditions at once.
The newborn screening test cannot be used to diagnose cystic fibrosis - it can only indicate whether CF is likely. While it can detect 85-90 per cent of likely cystic fibrosis cases, further testing is needed to confirm the diagnosis.
If the newborn screening test indicates possible cystic fibrosis, a sweat test or genetic test (or both) will be recommended. Sweat tests are also recommended for children and adults who were were not picked up by screening and have signs and symptoms and/or a family history suggesting cystic fibrosis.
A sweat test involves using a chemical to stimulate sweating on a small area of the arm. Sweat is collected from the area in a tiny tube and the amount of salt in the sweat is measured.
A positive result (more salt than normal) confirms the diagnosis of cystic fibrosis. A negative or inconclusive result means CF is unlikely but further testing may be recommended.
Genetic testing can be done to diagnose CF and work out the exact type of gene mutations you have inherited. Your doctor may want to know the types of mutations when prescribing specific treatments.
Ongoing tests for people with CF
If you or your child are diagnosed with cystic fibrosis you will be referred to a specialist CF centre. Tests such as lung function tests, blood tests and chest X-rays are regularly recommended to monitor your condition.
Treatments for cystic fibrosis
Lifelong treatment is needed for cystic fibrosis, as currently there is no cure. But recent improvements in treatments have lead to better control of the condition and a much improved outlook.
Treatment for cystic fibrosis requires regular visits to your GP (general practitioner) and specialist CF centre (where you have access to doctors, specialist nurses, dietitians and physiotherapists). Treatment aims to relieve symptoms, prevent and treat infections and reduce the risk of complications.
Treating lung and airway problems
The most common problem for people with cystic fibrosis is increased thick mucus in the lungs that leads to recurrent or ongoing infections and inflammation. There are various treatments to help control these problems.
Regular chest physiotherapy is important to help loosen and clear the thick mucus out of the airways in the lungs. Chest physiotherapy aims to clear the airways by helping you cough up the thick mucus. Intensive daily treatment is often needed.
More frequent chest physiotherapy is needed whenever you have a chest infection.
Special breathing techniques can also help clear the airways. Mechanical devices, such as positive expiratory pressure masks and vibrating vests can also be used to help loosen mucus in the lungs.
There are several different types of medicines that can help treat cystic fibrosis. These include:
- Medicines that make mucus thinner and easier to cough up - so-called mucolytics such as nebulised dornase alfa (brand name Pulmozyme), nebulised saline or inhaled mannitol (brand name Bronchitol).
- Medicines to reduce and control lung and airway inflammation - including inhaled or oral antibiotics and anti-inflammatory medicines (such as ibuprofen).
- Medicines that help open up the airways (such as inhaled salbutamol - brand name Ventolin).
Side effects depend on the treatment - your doctor will inform you of the common side effects and precautions that should be taken with any medicines that are prescribed.
Antibiotics for chest infections
Antibiotics are frequently needed to treat chest infections in people with CF. Starting antibiotics at the first sign of a chest infection is important. This helps you get better faster and reduces lung and airway damage from inflammation caused by the infection.
Antibiotics can be given as powder or solution to be inhaled or as tablets or capsules to be swallowed (or both). More serious infections may need to be treated with intravenous antibiotics (given via a drip into a vein).
Some types of infections - such as Pseudomonas aeruginosa or Burkholderia cepacia - can become resistant to antibiotics and difficult to treat. Chronic (ongoing) infections such as these are associated with more severe illness.
Treating digestive problems
A healthy diet is very important for people with cystic fibrosis. It’s usually recommended that you see a dietitian, who will give you a specific diet to follow. Most people with CF should eat a high salt diet with added vitamins. Drinking plenty of fluids also helps thin mucus, and extra water and salt intake may be needed in hot weather. A high energy diet is usually recommended for those who are undernourished.
Most people with CF will also need to take pancreatic enzyme replacement tablets before meals and snacks to aid digestion. This helps with the absorption of nutrients from food to help make sure you have adequate nutrition and calorie intake to maintain a healthy weight.
People with CF who have had bowel obstructions in the past may need to take stool softeners, laxatives and other treatments to keep their bowel habits regular and prevent constipation.
Newer medicines for CF
A newer class of medicines called cystic fibrosis transmembrane conductance regulator (CFTR) modulators are available in Australia. CFTR modulators target the abnormal CFTR protein in people with CF, improving its function, which in turn thins the mucus in the lungs and other organs. However, these medicines don’t work for all people with cystic fibrosis. Whether these medicines are effective for you will depend on the type of CF gene mutation you have inherited.
Examples of CFTR modulators currently available in Australia include ivacaftor (brand name Kalydeco), ivacaftor plus lumacaftor (brand name Orkambi) and ivacaftor plus tezacaftor (Symdeko). Further medicines in this class are being developed to target different gene mutations of the CFTR protein.
A yearly flu shot is recommended for people with cystic fibrosis. Keeping up to date with recommended vaccinations in childhood and as you get older is especially important for people with cystic fibrosis.
Organ transplantation is one of the newer treatments helping people with severe cystic fibrosis.
Lung transplantation may be offered to some people with severe lung disease that is not responding to other treatments. Liver transplants may be an option for people with cystic fibrosis who develop cirrhosis of the liver.
Ongoing research on manipulating the genes responsible for inherited diseases provides hope for a cure for CF in the future.
Support for people with cystic fibrosis
Support is available for people living with cystic fibrosis and their families. Having a serious, lifelong illness can be difficult to deal with at times, and talking to other people and families who are in the same situation can be really helpful.
Talking to others about managing day-to-day medical needs and dealing with limitations on what you can eat and do may help you feel less alone. Sharing self-care tips and recommendations is another benefit of support groups.
Online and face-to-face support is available - ask your doctor or search online for support that suits your needs.
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4. Royal Australian College of General Practitioners (RACGP). Genomics in general practice: Cystic fibrosis. https://www.racgp.org.au/clinical-resources/clinical-guidelines/key-racgp-guidelines/view-all-racgp-guidelines/genomics-in-general-practice/cystic-fibrosis (accessed Apr 2019).