Kalydeco® (ivacaftor, a CFTR potentiator) was approved by U.S. Food and Drug Administration to treat CF patients with G551D and other nine class III and IV mutations (G178R, S549N, S549R, G551S, G1244E, S1251N, S1255P, G1349D and R117H) [42]. Here, CFTR is linked to cystic fibrosis.