Cystic fibrosis (CF) is a rare genetic disease caused by pathogenic variants in the CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) gene, with wide clinical variability influence not only by the CFTR genotype but also by environmental and modifier genes such as ADAM33 (A Disintegrin and Metalloproteinase Domain 33). The gene discussed is ADAM33; the disease is cystic fibrosis.