Patients with the rs193922525 AG genotype (one copy of the CFTR G1349D variant) and cystic fibrosis may respond to ivacaftor treatment. FDA-approved drug labeling information and CPIC guidelines indicate use of ivacaftor in cystic fibrosis patients with at least one copy of a list of 33 CFTR genetic variants, including G1349D. Other genetic and clinical factors may also influence response to ivacaftor.