The issue with metabolism
Cystic Fibrosis (CF) is the most common metabolic disease. In Switzerland and Germany 1 of 2,000 newborn children is affected. It's inherited recessive which means that both parents need to be bearer of the defect (but they are not sick). The chance that their child will have CF is 25%, there's a 50% chance that it's also bearer of the defect but not sick and another 25% that it is not even bearing the defect.
Due to the genetic mutation, the chlorid-ion-channel in the cells are either narrowed or missing completely, it depends of the type the of the mutation (there are approximately 1,000 different types of the defect). Beacuse of these deficient channels the exchange of chlorid ions between the inside and outside of the cells is limited or not happening at all. Therefore there's hardly any osmosis (exchange of water) and this missing water in the organs (mainly the lungs and the pancreas) is causing viscous secretion for example in the bronchia.