CFTR and exocrine pancreatic insufficiency: Cystic fibrosis (CF; OMIM number 219700) is an autosomal recessive disease caused by mutations in the CFTR (cystic fibrosis transmembrane conductance regulator) gene, which results in abnormal viscous mucoid secretions in multiple organs and whose main clinical features are pancreatic insufficiency, chronic endobronchial infection, and male infertility.