CFTR and cystic fibrosis: CF is an autosomal recessive disorder caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR), which primarily functions as a chloride channel, but additionally plays several regulatory roles, including, importantly, the inhibition of the epithelial Na+ channel (ENac)—which facilitates intracellular sodium transport from the extracellular space.