Cystic fibrosis: fast facts
Q: What is Cystic Fibrosis?
A: Cystic Fibrosis is the most common serious genetic condition in Australian children today, affecting one in every 2500 babies.
Q: What happens?
A: In people with CF, the mucus secretions produced by various glands in the body are thicker and stickier than normal. This mucus clogs the tiny passages in the lungs and traps bacteria. Repeated infections and blockages can cause irreversible lung damage. The pancreas is also impaired, preventing the release of enzymes which are needed for the digestion of food. This means that people who have CF can have problems with digestion and nutrition.
Q: Who gets CF?
A: CF is an inherited condition. For a child to be born with CF both parents must carry the CF gene. Carriers of the gene do not have any symptoms of the condition.
Q: How common is CF?
A: One in 25 people carries the CF gene. One in every 2500 babies is affected by CF. CF affects males and females equally.
Q: How is CF diagnosed?
A: In Australia, all babies are screened at birth for CF. A blood spot test is carried out. If the test is positive, a sweat test will be done to measure the amount of salt in the sweat. A positive result confirms the diagnosis; a negative result may call for specific genetic testing. However, while newborn screening has improved the early detection of CF, some cases will not be picked up until symptoms appear later in childhood.
Q: Are there any pre-natal or screening tests for CF?
A: Genetic carrier testing is available, and 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. Your doctor or a genetic counsellor can advise you on this type of test. Carrier testing is complex, as over 1000 different gene abnormalities can lead to CF. Most laboratory tests only look for the 40 most common, which are responsible for about 85% of CF cases.
There are also special tests that can be used 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.
Q: What are the symptoms of CF?
A: A persistent cough, which usually contains sputum, or a cough that occurs with physical effort; some difficulty with breathing, or wheezing with effort; frequent chest and sinus infections; tiredness and lethargy; diarrhoea; stools that float and may be difficult to flush; recurrent abdominal pain; poor appetite. Salt loss in hot weather may produce weakness.
Babies with CF may develop a bowel obstruction (meconium ileus) in the first few days of life. In babies who are not diagnosed early with CF, the first signs of the disease are often failure to thrive (where they don’t gain weight normally) and/or recurrent chest infections.
Q: What complications does CF cause?
A: Children with CF tend to have recurrent chest infections and breathing problems. As children get older, their lungs may become permanently damaged.
Because the pancreas doesn’t produce the usual enzymes and secretions necessary for digestion, people with CF can have problems with malnutrition. Also, about 40 per cent of people with CF will develop diabetes, and some will develop problems with their liver.
Q: How is CF treated?
A: The CF gene was identified in 1989. This has led to the development of a carrier test, improved treatment and better control of the condition.
Many people with CF need to have intensive daily chest physiotherapy to break up the build-up of mucus in the lungs. Some people are also helped by inhaled medicines that can open up the airways and make mucus thinner and easier to cough up. They also need frequent antibiotics to treat chest infections.
Most people with CF will also take up to 40 enzyme replacement tablets each day to aid digestion. They must also follow high-energy diets with added vitamins and salt.
Vaccinations against influenza and pneumococcal disease are also recommended for people with cystic fibrosis.
Regular visits to CF clinics, hospitalisation and antibiotic treatment are common for people with CF.
Lung and liver transplants are now being performed in more severe cases.
How is CF inherited?
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 — these people, so-called ‘asymptomatic carriers’ do not have the disease or any symptoms.
If a healthy couple each carry a CF gene, 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 an asymptomatic carrier; and a one in 4 chance the child will neither have CF nor be a carrier.
Q: Is there a cure for CF?
A: CF is not curable at this time, but with today's improved treatment most people with CF are able to lead reasonably normal and productive lives.
Ongoing research on manipulating the genes responsible for inherited diseases provides hope for a cure for CF in the future.
2. Cystic fibrosis [revised Feb 2015]. In: eTG complete [Internet]. Melbourne: Therapeutic Guidelines Limited; (accessed Sept 2015). http://www.tg.org.au/
3. Cystic Fibrosis Victoria. Carrier screening. http://www.cysticfibrosis.org.au/vic/carrier-screening (accessed Sept 2015).