Is it possible she meant Class III? Classes are used to describe the extent to which the cftr is functioning or not functioning. For example if you have DeltaF508 mutation, you are a class I or II (I forget which), meaning that your cftr does not function at all. Anyway, if it is class III, Steve from Ambry might be better able to answer questions about mutation classes.
Class I through III mutations tend to have pancreatic insufficiency. Class III and IV have some chloride ion transport but function improperly (to really simplify it). Interestingly, class is not an indicator of pulmonary symptoms but there is some research out there that suggests those in class III or higher may be less frequently colonized with pseudo a. or their colonization may happen much later.