Cystic Fibrosis is the most common serious hereditary disease in the UK. Find out what causes it and how it's treated.
What is it?
Cystic fibrosis affects over 7,500 people in the UK. It's caused by inheriting two copies of a faulty gene, one from each of our parents. One in 25 people has one faulty gene, which is completely normal, but people with two faulty genes suffer from a wide range of problems throughout the body.
The CFTR gene
All of us have two copies of the Cystic Fibrosis Transmembrane Conductance Regulator - or CFTR - gene. This is a protein found in many different parts of the body, including the liver, lungs, gut, skin and sex organs. It works by transporting salt and water in and out of the cells that line the lungs and digestive system.
Patients with cystic fibrosis have two faulty copies of the CFTR gene, and they usually give out too much salt and too little water, producing mucus which is too thick around the lungs, and producing extra salt in their sweat.
Symptoms of cystic fibrosis
The symptoms of cystic fibrosis vary with age, but they can be detected as early as the newborn period.
- In the first few days of life, newborns may not pass faeces or may vomit uncontrollably;
- At this age, babies may also grow slower than expected. This is because their thick mucus blocks the release of normal gut enzymes which break down food, and they cannot gain enough nutrition from normal feeding.
- Older children and adults still have problems with malnutrition and constipation;
- As a child gets older, recurrent chest infections become a big problem. Mucus clogs up the smaller airways, making it easier for bacteria to grow in the lungs and causing inflammation and long-term lung damage. The child normally has a persistent cough and produces lots of phlegm;
- With time, diabetes also becomes a major issue, as the pancreas becomes damaged after years of blockage, and no longer produces enough insulin for the body's needs;
- In addition, many people with cystic fibrosis, especially men, are found to be infertile. Men often lack a vas deferens, the tube down which sperm travels from the testes to the penis. In women, thick mucus often makes it difficult for sperm to enter the egg;
- Bile ducts may also become blocked by mucus, leading to the formation of gallstones or liver damage;
- Some patients also have other airway problems aside from infection. Nasal polyps - small overgrowths of nasal tissue - can form as a result of long-term inflammation. These can cause difficulty breathing as they block up the nasal passages;
- There may be increased risk of getting a collapsed lung.
Testing for cystic fibrosis:
- Most cystic fibrosis cases are detected in the newborn period through a blood test taken when the baby's a few days old. Cystic fibrosis babies have higher levels of an enzyme called trypsin in the blood, and this is used in diagnosis;
- A sweat test can also be used to detect cystic fibrosis. Sweat is collected and measured for its levels of Sodium and Chloride;
- Cheek cells can be analysed to look for the faulty CFTR gene. This is a simple process, where a brush is rubbed against the inside of the cheek to pick up the relevant cells.
There is no definitive cure for cystic fibrosis, and cystic fibrosis patients have a reduced life expectancy, with most not surviving beyond their 30s, but there are treatments to help reduce certain symptoms:
- Intensive physiotherapy can help to dislodge thick mucus from the lungs, reducing the risk of infection. Older children can learn certain exercises to help do this themselves;
- Antibiotics are used to help treat chest infections;
- Vaccinations are given against disease such as whooping cough and pneumonia, helping to prevent any future lung disease;
- Enzyme capsules can be taken before meals to help digest food and prevent malnutrition;
- A high calorie diet helps to combat malnutrition;
- Insulin can be used if diabetes develops.
Future hope for a cystic fibrosis cure relies on gene therapy, and developing techniques for replacing the faulty CFTR gene with normal copies. This isn't currently available to patients and research is still ongoing. Lung transplants are sometimes carried out on patients with very severe disease to help relieve symptoms.
Written by Alex Jewkes
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