| Cystic fibrosis – getting up to date
Cystic fibrosis is an inherited, life-limiting condition that can’t be cured. Dr Kerry Robinson looks at the causes of CF and the government’s plans to test all newborn babies At the moment only 20% of babies in the UK are screened at birth for cystic fibrosis but this will change as universal testing for newborns is introduced across the country this year. CF affects approximately 7,500 people in the UK who have a life expectancy of about 30 years. Most children are only tested if they show signs or symptoms of the disease but an early screening programme would mean that doctors could treat babies with cystic fibrosis, prevent their lung function deteriorating and improve their quality of life. The chances of having the disease Even if there’s no family history of Cystic Fibrosis (CF) you still have a 1 in 2500 chance of having a child with CF. This may not sound high, but it’s the equivalent of 25 people watching a football match at a packed Old Trafford stadium. Unfortunately, the disease is inherited. It’s in our genes, in groups of chromosomes and the gene for CF is found on chromosome number 7. We inherit half our genes from our mothers and the other half from our fathers. To develop CF we need to inherit one gene coding for CF from our mother and another from our father. In other words two CF genes are needed for the illness to develop. If we just have one CF gene (a faulty gene from our mother but a normal one from our father), we do not develop the illness but we’re a carrier and there’s a risk we could pass the gene to our children. 1 in 25 people in the UK are carriers. What is Cystic Fibrosis? It’s caused by a faulty transport of salt across certain cell membranes. This results in a thick, sticky mucous being excreted by the cells which causes problems mainly in the lungs and the pancreas. It clogs the tiny airways in the lungs predisposing people to chest infections and it obstructs the outflow of the pancreas, preventing enzymes from reaching the intestines to help break down and digest food.
Testing for CF People with CF have a range of symptoms including very salty tasting skin, persistent cough and frequent chest infections, big appetite but poor weight gain and bulky stools that are hard to flush down the toilet. Diagnosis involves collecting a sample of sweat and testing the amount of salt in it. High levels are indicative of CF and a blood test will be taken to look at the chromosomes. Genetic tests can identify the faulty gene. Current treatments Treatment depends on which organs are involved. Many children with CF suffer persistent chest infections, which are slow to clear and a two week course of intravenous antibiotics is often needed. Daily physiotherapy is also recommended to help clear the chest of thick mucus. When CF affects the digestive system, enzymes taken in the form of pills may be prescribed before meals to help the body digest food and absorb nutrients. Screening In future, screening tests will be carried out on a drop of dried blood on the Guthrie card. All babies have a Guthrie test when they’re one week old to test for thyroid disorders and phenylketonuria (a metabolic disease which causes brain and nerve damage) and the test for Cystic Fibrosis will be routinely added to the list. A major step forward In 1989 researchers identified the faulty CF gene and the theory is that we could cure cystic fibrosis if we could get a good gene into the body to replace the faulty one. However, delivering genes that the body will accept is a complex procedure. It has been done in America in 1993 but when the corrected lung cells died, the cells that grew in their place were coded with the faulty CF gene. Clinical studies in the UK have shown that to be effective, the replacement genes need to be stronger and more resilient. So the research continues and there are several projects underway here. Hopefully, in the future gene therapy will reduce lung damage, improve life expectancy and decrease morbidity. In the meantime, early screening will allow prompt and aggressive treatment of the disease and improve the prospects for young children with cystic fibrosis. Support groups and information…
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