This is the most common serious genetic disease in Caucasian children, with an incidence of about one per 2,500 births, and more than 10,000 patients in the UK. It is an autosomal recessive disorder of the mucus-secreting glands of the lungs, the pancreas, the mouth, and the gastrointestinal tract, as well as the sweat glands of the skin. The defective GENE is sited on CHROMOSOME 7 which encodes for a protein, cystic fibrosis transmembrane conductance regulator (CFTR). Individuals who inherit the gene only on one set of chromosomes can, however, carry the defect into successive generations. Where parents have a child with cystic fibrosis, they have a one-in-four chance of subsequent children having the disease.
The disorder is characterised by failure to gain weight in spite of a good appetite, by repeated attacks of bronchitis (with BRONCHIECTASIS developing at a young age), and by the passage of loose, foul-smelling and slimy stools (faeces). AMNIOCENTESIS, which yields amniotic fluid along with cells shed from the fetus's skin, can be used to diagnose cystic fibrosis prenatally. The levels of various enzymes can be measured in the fluid and are abnormal when the fetus is affected by cystic fibrosis. Neonatal screening is undertaken on all UK born babies using a test on blood spots – immunoreactive trypsin (IRT).
In children with symptoms or a positive family history, the disease can be tested for by measuring sweat chloride and sodium. This detects the abnormal amount of salt that is excreted via the sweat glands when cystic fibrosis is present. Confirmation is by genetic testing.
This consists basically of regular physiotherapy and postural drainage, antibiotics and the taking of pancreatic enzyme tablets and vitamins. Some children need STEROID treatment and all require nutritional support. The earlier treatment is started, the better the results. Whereas three decades ago, only 12 per cent of affected children survived beyond adolescence, today 75 per cent survive into adult life, and median survival is to 41 years. Patients with end-stage disease can be treated by heart-lung transplantation (with their own heart going to another recipient). Research is underway on the possible use of GENE THERAPY to control the disorder.