Cystic fibrosis (CF)patients present mutations of the cystic fibrosistransmembrane conductance regulator (CFTR) gene, which codes for acyclic AMP-regulated chloride ion channel.1 Loss of function of this channel leads to defective transport ofchloride ion across the surface of epithelial cells, which in turninterferes with the clearance of inhaled microorganisms. This evidence concerns the gene CFTR and cystic fibrosis.