What is Cystic Fibrosis?
Cystic fibrosis (CF) is an inherited genetic disease affecting a number of organs in the body (especially the lungs and the pancreas) by clogging them with thick, sticky mucus.
At present there is no cure for CF but the faulty gene responsible for causing the disease has been identified. Clinical trials of gene replacement therapy have commenced and it is hoped that a treatment may be available in the future.
CF is more common in the Caucasian population. The disease affects around 100,000 people worldwide and more than 10,500 in the UK. Advances in treatment since the 1960s have greatly increased the life expectancy of a baby born with CF - in the UK around half of people with CF will now live past 40 while babies born today may live even longer.
What are the symptoms of cystic fibrosis?
CF causes the body to produce thick secretions, particularly in the lungs and the digestive system. This causes symptoms such as cough, repeated chest infections, prolonged diarrhoea and poor weight gain. The disease is normally diagnosed at birth or soon after. Babies may be born with a blocked bowel, have poor growth patterns and suffer from chest infections.
The thick, sticky mucus in the lungs of people with CF makes them more susceptible to infections, which cause the lung tissue to become inflamed. Over a period of time the lungs become scarred and damaged.
The mucus also causes damage to the pancreas - this prevents the release of the enzymes needed to digest food. People with CF are therefore at risk of malnutrition, which can in turn increase their risk of osteoporosis. The use of steroids in adults with CF can also increase the risk of osteoporosis.
In men the tubes that carry sperm can become blocked, causing infertility.
Liver disease can also occur later in life, as a result of small ducts in the liver becoming blocked. In some cases a liver transplant may be required.
How is cystic fibrosis diagnosed?
Newborn babies can be tested for CF using a heel prick blood test. If screening tests on a newborn baby are abnormal a sweat test will be conducted - children with CF have higher than normal levels of salt in their sweat. A genetic test is available to confirm the diagnosis - this involves gently rubbing the inside of the cheek with a brush to obtain a specimen of cells which can then be tested for the CF gene. Antenatal testing is available to determine whether a baby will be born with CF; this type of screening is only offered in cases where there is a high risk of CF.
What causes cystic fibrosis?
Cystic fibrosis is an inherited genetic disease. Carriers of the faulty gene responsible for causing the disease are completely healthy and do not have the disease themselves. In the UK, around one person in 25 is a carrier of the faulty CF gene but a baby can only be born with CF if both parents carry the faulty gene. The gene can be carried and passed on by each generation undetected.
If both parents carry the CF gene, a baby has a one in four chance of inheriting the disease and a two in four chance of not having the disease but of being a carrier of the faulty gene. One in four babies will be totally free of the disease and of being a carrier. If either the mother or father has CF, the chance of passing it on to a child is one in 50. CF affects an equal number of males and females.
Genetic counselling will be offered to families affected by CF. A simple swab from the mouth can detect the existence of the faulty CF gene. The test will be offered to those who have a relative with CF or are at risk of having a baby born with CF. Currently, the NHS does not conduct routine screening of the general population to look for the CF gene, although screening is available privately.
If a family already has a child with CF, the parents will be offered genetic screening for any subsequent pregnancy. This involves taking a small sample of the placenta (a chorionic villus sample [CVS]) 10 to 12 weeks into the pregnancy which is then tested for the CF gene. Alternatively, amniocentesis (to obtain a sample of cells from the foetus) can be carried out at around 17 weeks. These procedures are not entirely without risk and may cause miscarriage.
Another, still experimental form of genetic screening is also available. This involves the use of IVF treatment to create several embryos which are then screened for the faulty gene before implantation. An embryo which does not carry the CF gene can be implanted back into the mother who will then undergo a normal pregnancy.
What treatment is available?
A cure for CF is not yet available. However, there is much research being undertaken in the area of gene therapy which may eventually offer a cure. For people who have certain specific genetic abnormalities, a tablet containing a drug called ivacaftor (Kalydeco®) or a combination of ivacaftor + lumacaftor (Orkambi®) can help treat the underlying cause of CF.
Replacement pancreatic enzymes need to be taken daily with or before meals to ensure food is digested. The available preparations contain an ingredient called pancreatin (eg, Creon®, Nutrizym®, Pancrease® and Pancrex®).
People with CF require daily treatment involving extensive physiotherapy and breathing exercises to keep their lungs clear of mucus. Antibiotics and anti-inflammatory drugs (eg, steroids) may be given to treat lung infections and inflammation of the lung tissue. Antibiotics are often given as inhaled therapy via a nebuliser device. Mucolytics, such as carbocisteine (Mucodyne) and mannitol (Bronchitol), may also be used to help clear the lungs of mucus.
In very severe cases of lung damage, respiratory failure will occur and a double lung transplant may be the only option. However, transplants often fail as a result of infection or rejection by the body's immune system. Research is being carried out to identify the reasons for this rejection. If successful, organ transplantation can vastly improve the quality of life for a person with severely damaged lungs. It is thought that around 70 per cent of CF patients survive for five years after a lung transplant.
Further Information available from:
Cystic Fibrosis Trust
London EC3N 1RE
Tel: 020 3795 1555
Helpline: 0300 373 1000/020 3795 2184 or firstname.lastname@example.org
Fact sheet provided by MIMS
Date last reviewed: September 2016
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