The mucus eventually reaches the mouth and is swallowed or blown out of the mouth. Patients with cystic fibrosis produce a sticky mucus, which is difficult to move and clear. This is probably because they are unable to move water into the airways from their epithelial cells. Serious lung infections are common, and can only be minimised by many hours of regular physiotherapy, which aims to expel the mucus from the body. Repeated lung infections seriously damage the lung tissues and place strains upon the heart.
Cystic fibrosis is a serious disease which is normally fatal in early adulthood.
This is largely due to the damaging effects on the lungs. This is one of the reasons why gene therapy techniques for cystic fibrosis are targeting lung tissues. Gene therapy aims to introduce functional copies of the cystic fibrosis genes into epithelial cells of the lung. There are other symptoms of cystic fibrosis, of course, associated with the other affected epithelial cells in the body. Patients produce salty sweat, which is one of the ways of diagnosing the disease.