CFTR and cystic fibrosis: Cystic fibrosis (CF) is a life limiting autosomic recessive genetic disease whose most frequent mutation is the deletion of phenylalanine 508 (p.Phe508del, F508del thereafter) in the first nucleotide-binding domain (NBD1) of the Cystic Fibrosis Transmembrane Conductance Regulator protein (CFTR)1.