Definition
Cystic fibrosis (CF) is a complex autosomal recessive disease caused by a mutation in a gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein, the main function of which is to regulate liquid volume on epithelial surfaces through chloride secretion and inhibition of sodium absorption. The disease mainly affects the upper and lower airways, but also the pancreas, bowel, liver and reproductive tracts. Lung disease, the cause of death in 85% of affected subjects, begins early in life and is characterised by impaired mucociliary clearance and consequent chronic airway inflammation and bacterial infection.
Prevalence
The prevalence of CF varies from country to country. It is most common in white populations of northern-European descent, in which it occurs in approximately 1 in 2500 births. CF is uncommon in Africa and Asia. In Europe, about one in 25 individuals carries a mutated CFTR gene but carriers do not have symptoms of the disease.
Clinical manifestations
CF manifests in many organs and, depending on the type of CFTR mutation and other factors, with different severity. The main symptoms of CF, which often appear in infancy and childhood, are fatty stools, poor growth and weight gain despite normal food intake, frequent chest infections, coughing and shortness of breath. In newborn babies, bowel obstruction due to meconium ileus can occur. Males can be infertile due to congenital absence of the vas deferens.
Diagnosis
The diagnosis of CF should be considered in any child or adult who presents with the signs or symptoms listed in the table. CF can be diagnosed by sweat testing. People with CF have increased amounts of sodium and chloride in their sweat (>60 mmol·L−1 diagnostic; 40–60 mmol·L−1 intermediate; <40 mmol·L−1, normal).
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The test needs to be performed by trained and experienced staff. CF can also be diagnosed by genetic …
