Cystic fibrosis (CF) is the most common life-threatening genetic disorder among Caucasians. It primarily affects the respiratory system (lungs), the digestive system (pancreas and sometimes liver) and the reproductive system.
When a person has CF, their mucus glands secrete very thick sticky mucus. In the lungs, the mucus clogs the tiny air passages and traps bacteria. Repeated infections and blockages can cause irreversible lung damage and a shortened life. The pancreas is also affected, preventing the release of enzymes needed to digest food. This means that people with CF can have problems with nutrition and must consume a diet high in kilojoules, fats, sugar and salts.
Carriers of a CF gene are healthy and often not aware that they are carriers. If you are planning a pregnancy, you can now have testing to clarify your status for cystic fibrosis.
In Australia, all babies are screened at birth for CF through the newborn screening test. This involves collection of a blood sample through a heel prick test immediately after birth. If the results of the screening test reveal very high levels of a substance called immune-reactive trypsin (IRT), CF is suspected and the DNA in the blood is then analysed for the most common mutations causing CF.
A sweat test may be done to measure the amount of salt (sodium chloride) in the sweat and confirm the diagnosis.
Some babies may also be diagnosed shortly after birth as a result of an intestinal blockage called meconium ileus. Most babies who have CF are now diagnosed within the first two months of life.
Special tests can be carried out during pregnancy to determine if the baby will have CF. They are available if you already have a child with CF or if you or your partner are genetic carriers for CF.
Genetic carrier testing is done for people who don’t have CF to find out if they have a mutation in one of their CFTR gene copies. Testing is usually done with a sample of saliva or blood. This is most needed for:
- The partner of a person already known to be a carrier of a CFTR mutation
- A close blood relative of a person with CF.
If you are considering genetic carrier testing, you are advised to consult a genetic counsellor who can provide advice and arrange testing.