Illustration of cystic fibrosis. It is characterised by thick, viscous mucus that prevents the digestive and respiratory tracts from functioning normally. The left-hand outline shows the organs affected by the illness: - The skin : abnormal sweat which is 3 to 5 times more salty. - The lungs : viscous mucus sticks to the bronchial tubes, making breathing difficult and increasing bronchial, viral and particularly bacterial infections. - The liver : affected in 15% to 20% of cases, thick bile blocks the biliary tracts preventing it from working properly. - The pancreas : affected in 80% of cases, mucus obstructs the pancreatic ducts preventing digestion enzymes from reaching the intestine. - The intestine : bad digestion causes abdominal pain and problems of digestive transit such as diarrhea or constipation. - The genital organs : male sterility in 98% of cases due to the tracts carrying the sperm being blocked. Sexuality remains normal however. The right-hand side explains the illness and its treatment. In the nucleus of our cells, the CFTR gene is the cause. It carries mutations in ill patients, preventing the protein CFTR in the cell membrane from working properly, ie from transporting water and salt into and out of the epithelium cells which results in thick and viscous mucus. A drug (VX-770 molecule) allows this membrane protein to open which enables chloride ions to be evacuated and blocks sodium ions.
