[Expression of the cystic fibrosis gene in the lungs]

Cystic fibrosis (CF) is one of the most common hereditary diseases with a potentially lethal outcome. CF is caused by mutations in a gene on chromosome 7 that encodes for a polypeptide called 'cystic fibrosis transmembrane conductance regulator' (CFTR). Pulmonary complications in CF are a direct consequence of a fault in the production or function of CFTR. The consequences of these faults are a change in the viscosity and volume of the air-surface liquid in the airways and possible malfunctioning of the immunological defence system. The result is stasis of mucus and obstruction of the smaller airways. Secondary to this process, a (chronic) infection with an uncontrolled inflammatory response, leads to destruction of lung tissue and a reduction in lung function. Mutations in CFTR can be classified in five types, which reflect the level of production or the function of CFTR. This classification permits discrimination between mild and severe mutations. The clinical image and the course of CF are often related to the combination of mutations present. This may explain, in part, why some CF patients are diagnosed at a later age with a normal sweat test and a clinical image that is predominantly limited to respiratory symptoms.