Patients with the rs397508288 GG genotype (two copies of the CFTR D579G variant) and cystic fibrosis may respond to ivacaftor treatment, as response may depend on the presence of other CFTR variants. 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 D579G. Other genetic and clinical factors may also influence response to ivacaftor.