CFTR and cystic fibrosis: Modulators that increasethe ion conductance of the CFTR protein are known as potentiators.Ivacaftor is the only potentiator approved as monotherapy in patientswith the G551D mutation.6,7 The most common classII mutation–and the most common CFTR mutation overall–isΔF508, with approximately 80% of patients with CF in Europehaving at least one such allele.2 ClassII mutations prevent the proper folding and assembly of the CFTR protein,which results in very few copies reaching the membrane, many of whichare dysfunctional.