For example, ivacaftor, a cystic fibrosis transmembrane conductance regulator potentiator, is indicated for the treatment of cystic fibrosis in patients aged 2 years and older who have defined mutations in the CFTR gene (G551D, G1244E, G1349D, G178R, G551S, S1251N, S1255P, S549N, or S549R). Here, CFTR is linked to cystic fibrosis.