Cystic fibrosis (CF)

Cystic fibrosis (CF) is a life-limiting genetic disorder. It affects the whole body, but mainly the respiratory system (lungs), the digestive system (the pancreas and sometimes the liver) and the reproductive system. CF is one of the most common life-limiting genetic disorders for which there is currently no cure.

How CF affects the body#

In a person with CF, the mucus produced by the body is very thick and sticky. This makes it difficult to clear mucus from the lungs, where it clogs the tiny air passages and traps bacteria. The result is recurring infections and blockages, which can cause irreversible lung damage over time.

Thick mucus in the digestive system can also block the flow of digestive enzymes from the pancreas to the small intestine. This makes it harder to digest fats and absorb some nutrients. As a result, people with CF can have nutrition problems and often need a diet high in energy (kilojoules), fats and salt.

People with CF may experience a range of effects, including poor appetite, poor growth and, in males, infertility.

Symptoms of cystic fibrosis#

Symptoms can vary, but may include:

• a persistent cough that sometimes brings up thick mucus
• difficulty breathing and wheezing
• frequent lung infections
• salty sweat - salt loss in hot weather may cause muscle cramps or weakness
• tiredness, lethargy or reduced ability to exercise
• poor growth or weight gain
• frequent visits to the toilet, with bulky, greasy stools
• diarrhoea or constipation
• CF-related diabetes

How CF is inherited#

CF is a genetic condition. People who carry a single copy of the CF gene change are healthy and usually do not know they carry it, because they have no symptoms.

In many populations, roughly one in 25 people carry a single copy of the CF gene change. A child can only have CF if they inherit a gene change from both parents.

If two carriers have a child, each pregnancy has:

• a one-in-four chance the child will have CF
• a two-in-four chance the child will not have CF but will be a carrier of the gene change
• a one-in-four chance the child will not have CF and will not carry the gene change

Around one in every 2,500 births is a child who has CF.

Diagnosis of cystic fibrosis#

In many places, most babies are screened for CF at birth through a newborn screening test. This involves taking a small blood sample with a heel-prick test soon after birth.

If the screening test shows very high levels of a substance called immunoreactive trypsin (IRT), CF is suspected, and the DNA in the blood is then analysed for the most common gene changes that cause CF. A sweat test may also be done to measure the amount of salt (sodium chloride) in the sweat and confirm the diagnosis.

Most people with CF are now diagnosed within the first two months of life. Some babies are diagnosed shortly after birth because of an intestinal blockage called meconium ileus.

Treatment for cystic fibrosis#

There is currently no cure for CF, and treatment can be intensive and time consuming. It aims to slow the progression of the condition and may include:

• medications that help correct the changes to the body’s cystic fibrosis transmembrane conductance regulator (CFTR) protein, which is what causes CF
• chest physiotherapy
• antibiotics
• inhalations given via a compressed air pump and nebuliser
• enzyme replacement capsules taken with meals and snacks
• a well-balanced diet high in protein, fat and energy (kilojoules)
• supplementary vitamins and salt supplements
• regular exercise

In some cases, a percutaneous endoscopic gastrostomy (PEG) may be used - a procedure in which a flexible feeding tube is placed through the abdominal wall into the stomach. Regular attendance at a major CF clinic is beneficial and recommended.

Carrier testing and genetic counselling#

If you are planning a pregnancy, you can be tested to see whether you carry the CF gene change. Carrier testing information and resources are available through CF support services.

If your child or another family member has been diagnosed with cystic fibrosis, or if CF runs in your family, it can help to speak to a genetic counsellor. Genetic counsellors are health professionals qualified in both counselling and genetics. As well as offering emotional support, they can help you understand CF and its cause, how it is inherited, and what a diagnosis means for your child’s health and for your family.

Genetic counsellors are trained to provide information and support that is sensitive to your family circumstances, culture and beliefs. If CF runs in your family, a genetic counsellor can explain what genetic testing options are available to you and other family members. You may choose to see one if you are planning a family, to learn your risk of passing the condition on to your child or to arrange prenatal tests.

Support#

A range of support groups and organisations can connect you with other individuals and families affected by CF, and provide information, practical help and emotional support.

Key points#

• The thick, sticky mucus of CF causes recurring infections and blockages, which can cause irreversible lung damage over time.
• CF is one of the most common life-limiting genetic disorders, and there is currently no cure.
• People who carry one copy of the CF gene change do not have any symptoms of the condition.
• A child can only have CF if they inherit a gene change from both parents.
• Treatment for CF can be intensive and time consuming.

Where to get help#