Conflict of interest: C.H. Goss reports grants from the Cystic Fibrosis Foundation, FDA Orphan Products Division and the National Institutes of Health, consultancy fees from Enterprise Therapeutics, payment or honoraria for lectures, presentations, manuscript writing or educational events from Gilead Sciences and Vertex Pharmaceuticals, support for attending meetings from Vertex Pharmaceuticals and Enterprise Therapeutics, participation on a data safety monitoring board or advisory board with Novartis, is deputy editor of Annals of the ATS, and has stock (or stock options) with Air Therapeutics. D.R. VanDevanter has no potential conflicts of interest to disclose.