Potentiator ivacaftor, the first CFTR-targeting drug, was recently approved by FDA/EMA, albeit for a rare mutation — G551D (Ramsey et al., 2011) and for other Class III CFTR mutations (Van Goor et al., 2014, De Boeck et al., 2013), which, altogether only target ~ 5% of CF patients worldwide. This evidence concerns the gene CFTR and cystic fibrosis.