Cystic fibrosis

What is Cystic Fibrosis?

Cystic Fibrosis (or CF) is an inherited genetic condition which is first seen in children. It affects those organs in the body which normally produce fluids necessary for certain body functions. These organs include the lungs, parts of the digestive system, pancreas, and liver. The inability to produce these natural fluids means that their normal function is impaired.

Cystic Fibrosis has existed for many years but was first recognised in the 1930s, however it was not realised until the 1940s that it is an inherited disease. Research has shown it occurs in 1 in 2500 of white caucasian children born.

Clinically, Cystic Fibrosis occurs in the form of repeated and often quite severe chest infections and also as an impairment of nutrition as food may not be digested and absorbed in the body efficiently.

Thirty or forty years ago, a baby born with Cystic Fibrosis might survive for a few months only. Now, 75% of babies survive to adolescence and many live well into adulthood thanks to earlier diagnosis, improved treatment and advice. This has come about with better counselling of parents and a commitment to be actively involved in the management of the patient.

Why does it occur?

The condition will occur as a result of a faulty gene inherited by the child from both parents. The way in which our bodies develop is determined by pairs of genes present in every cell in our body. We inherit one of each pair from our mother and the other from our father. Which ones are inherited is determined by chance. The child must have inherited a faulty gene from both parents in order for the disease to become manifest.

About 1 in 25 of the population carries only one defective gene and is known as a carrier of the defective Cystic Fibrosis gene. Cystic Fibrosis carriers are completely healthy because they have one normal gene which overrides the defective one, and so prevents the disease from occurring. In genetic terms therefore Cystic Fibrosis can be referred to as an autosomal recessive condition.

However, if both parents are carriers of the defective gene, then it is probable that their child will have a 1 in 4 chance of contracting Cystic Fibrosis, a 1 in 2 chance of being a carrier (but completely healthy), and a 1 in 4 chance of being totally unaffected.

How does it occur?

The underlying basis of the disease is the excessive production of thick sticky mucus, which clogs the tiny airways in the lungs and also blocks the action of the pancreas.

As the small airways become plugged with mucus, the lungs become more susceptible to infection due to bacteria trapped in the airways. They become less efficient at clearing mucus and so further infection can occur.

The pancreas is a gland situated behind the stomach and which normally produces the chemical enzymes, which help us to digest the food we eat.

The digestive enzymes pass en route to the intestine via draining ducts, which if they become blocked, can result in defects in food absorption. As a result growth and development impairment can also occur.

Symptoms of Cystic fibrosis

Cystic Fibrosis can become apparent in a variety of ways during early childhood and may progress further into adulthood.

• Meconium Ileus: The first bowel motion in the newborn baby is a thick black material called meconium. In Cystic Fibrosis, the meconium can become so thick (due to abnormal content of bowel fluids) that the bowel can become blocked. This is called meconium ileus and a simple operation carried out at the time of diagnosis will relieve the problem quickly.
• Nutritional problems in infancy: Beyond the newborn period, failure of digestion and absorption will impair nutrition. This is seen in infants as a failure to gain weight. The child often appears pale and thin and the bowel motion will also appear pale, greasy and smelly. This is because the normal digestive juices from the pancreas and bile pigment, are prevented from being secreted into the bowel.
• Chest and Respiratory problems: Later on the older child may be subject to repeated chest infections as the airways become blocked with infected mucus. In the early years the infections are commonly caused by viruses and bacteria called staphylococcus aureus and haemophilus influenza. Later on the infections are caused by a bacteria called pseudomonas aeruginosa. These can be detected by examining the coughed up secretions microscopically. The treatment is decided on the basis of detecting the viruses and bacteria responsible for the infection. They may also develop a persistent cough or wheezing. There is also a possibility of repeated sinus infections.
• Nutritional problems in adulthood: As adults there are the possibilities of developing diabetes or cirrhosis of the liver. There may be complications with male fertility and constipation. As age progresses there is the risk of developing osteoporosis due to lack of absorption of vitamin D and calcium, which is needed for healthy bones.

What are the tests?

The diagnosis is made by two tests:

Early infant screening test: This takes the form of a heel prick blood test performed at 10 days old by the health visitor. The blood is examined in the laboratory for evidence of Cystic Fibrosis. If abnormal the test will be repeated. Should the test remain abnormal then the child will be referred on to a paediatrician who will arrange other tests including a sweat test.

Sweat Test: The basis of the test is that children with Cystic Fibrosis have more salt in the sweat than the normal child. In this test, the amount of salt in the sweat is measured. This is quite a painless procedure and involves collecting sweat samples over a 10 -30 minute period and sending it for salt analysis. If the salt level is abnormally high (and this can be measured), then almost certainly the child has the condition.

Cystic Fibrosis treatment

There is no definite cure for Cystic Fibrosis but much can be done to control the symptoms, and the parents of affected children have a large part to play in administering prescribed treatment with the aim of helping them lead an active and fulfilling life.

Physiotherapy: Daily chest physiotherapy is important to help prevent excessive build up of mucus in the lungs. Parents can learn the techniques early on and children should be encouraged to be active and take responsibility for their own physiotherapy and breathing exercises.

Drug therapy: Prompt treatment with antibiotics or anti-fungal medication to treat chest infections are important measures. The use of inhalers is also important to dilate airways and aid breathing.

Diet: All children with Cystic Fibrosis should have food which is high in calories, high in fibre and high in fat. The doctor will prescribe a pancreatic enzyme tablet (called pancreozymin) to replace that which the pancreas cannot produce. This combination will help maximise food absorption and therefore the general nutritional state. The doctor may also prescribe vitamin supplements, as vitamins from the diet are sometimes not absorbed very well despite the use of the enzyme replacement.

Surgery: In very severe cases a lung transplant may give a new hope for improvement and a better quality life, but surgery has risks and should be considered carefully.

Gene therapy: With the isolation of the faulty gene, research has centred on gene therapy to replace the defect and there is still research currently under way and the results awaited.

New drugs are being tested which may alter the salt and water regulation within the body's cells that cause the thickening of mucus and secretions.

Medications

• Digestive enzymes.
• Antibiotics when lung infections occur.
• Enzymes by nebulizer to help loosen lung secretions.

Information

Brand

Generic

Label

Zithromax

Azithromycin

Cipro

Ciprofloxacin

Motrin

Ibuprofen

Keflex (Cephalexin), Atrovent (Ipratropium bromide), Prilosec (Omeprazole), Flonase (Fluticasone inhalation), Decadron (Dexamethasone)

Genetic counselling

Should there be a family history of Cystic Fibrosis then it is possible to get genetic counselling. There is a simple test that can be done. It requires taking a few cells from the inside of the mouth with a swab. The test will detect if the faulty gene is present and therefore the person is a carrier of the disease.

Last updated 3 April 2018