CFTR and cystic fibrosis: In a subset of individuals with NCFBE, pathogenesis is likely due–at least in part–to CFTR deficiency, originating from inherited factors (i.e., asymptomatic CF carrier status, which occurs in approximately 1 of 30 US Caucasians and leads to ~50% decrease in CFTR mRNA and protein), acquired factors (e.g., due to chronic airway inflammation, infection, hypoxia, or toxin exposure), or a combination of these.