Cystic fibrosis

• Cystic fibrosis is an autosomal recessive disorder.
• Cystic fibrosis is a multi-system disease.
• Cystic fibrosis is caused by impaired chloride ion transport resulting in abnormally concentrated fluid on epithelial surfaces.
• The incidence in the UK is approximately 1 in 2500 live births and the carrier frequency is 1 in 25.
• Cystic fibrosis is the result of the most common genetic mutation in the UK is ∆F508.
• There are approximately 7500 children and adults with cystic fibrosis in the UK.
• Median life expectancy is 34 years.

Cystic fibrosis is an inherited disease with what is technically known as autosomal recessive transmission. It is the most common, life-threatening, inherited disease in the UK. 

It predominantly involves the respiratory and gastrointestinal systems, although liver disease, arthropathy, diabetes and infertility are also associated complications. Normally, cells in the body make secretions and mucus, but in cystic fibrosis these cells do not work properly and the secretions and mucus are much thicker than they should be. This thick, sticky mucus then causes blockages in the lungs and digestive tract, making it difficult to breathe and digest food properly.

The prevalence of the disease is higher in Caucasian populations than in those of other ethnic groups, with a frequency estimated at 1 in 2500 births (McAuley and Elborn, 2000). This compares to an incidence of 1 in 3500 in the USA, 1 in 1800 in Ireland and 1 in 2500 in

Cystic fibrosis is caused by a single gene defect on chromosome 7. This genetic defect leads to the production of an abnormal protein called the cystic fibrosis transmembrane regulating protein (CFTR). In patients with cystic fibrosis, chloride ion transport is impaired, resulting in an abnormally concentrated fluid on the epithelial surfaces of the lungs and other organs. This makes the airway secretions viscous and difficult to clear, which predisposes the patient to a variety of bacterial infections and consequent lung damage (Dinwiddie, 1999).

Approximately 1 in 25 people carry this genetic defect. A baby born to parents who are both carriers of this gene will have a one in four chance of having the condition. If a child inherits just one cystic fibrosis gene, they will also become a carrier but will not develop the condition.

Cystic fibrosis is a ‘multi system’ condition - this means that the excessive build-up of thick mucus affects several organs in the body, although primarily the lungs and digestive tract are affected.

Symptoms will usually develop before a baby reaches a year old although some children can develop symptoms later in their childhood.

Lungs

In a healthy person, a continuous flow of mucus helps remove bacteria from the surfaces of the air passages in the lungs. With cystic fibrosis, this mucus is thick and sticky so is unable to remove bacteria effectively - the mucus also provides a perfect environment for the bacteria to live and grow, so an individual with cystic fibrosis is more at risk of contracting bacterial infections. If these infections are not treated promptly they can be very hard to remedy and this can lead to permanent lung damage.

Digestive system

Cystic fibrosis also affects the