CF is caused by bi-allelic deleterious mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein, leading to defects in chloride and bicarbonate ion transport across epithelial surfaces, and consequently the production of thick secretions that disrupt mucociliary clearance in the lungs, predisposing to chronic bacterial infections, and progressive inflammatory lung disease. Here, CFTR is linked to cystic fibrosis.