CFTR and cystic fibrosis: Although the current study focused only on ivacaftor use among individuals with a G551D mutation, highly effective modulator therapy is now available for many CF patients with other ivacaftor-responsive variants (10–15% of patients) and/or a copy of the most common CFTR variant, F508del corresponding to treatment with elexacaftor/tezacaftor/ivacaftor therapy (currently totaling 94% of the U.S. population, given latest FDA approvals) [22–24].