Cystic fibrosis (CF)is caused by dysfunction of mucociliary clearance from the airways,due to a mutation in the cystic fibrosis transmembrane conductanceregulator (CFTR) gene. This mutationresults in impaired mucociliary clearance, leading to mucus accumulation,increased susceptibility to bacterial infections, exacerbated inflammatoryresponse and airway obstruction. This evidence concerns the gene CFTR and cystic fibrosis.