CFTR and cystic fibrosis: The etiology of CF is a mutation of the gene encoding the CF transmembrane conductance regulator (CFTR) protein, which was first described in 1989 by Kerem et al. (1989), Riordan et al. (1989), and Rommens et al. (1989) and is commonly expressed within epithelial cells where it normally functions as an anion, predominantly chloride ion, channel (Elborn, 2016).