Kalydeco (ivacaftor, VX-770) is the first approved potentiator for the treatment of CF patients with the G551D-CFTR mutation [24] or some other rare gating mutations including G178R, S549N, S549R, G551S, G1244E, S1251N, S1255P and G1349D mutation [25]. Here, CFTR is linked to cystic fibrosis.