From Manchester University NHS Foundation Trust, Manchester, United Kingdom (P.J.B.); Charité-Universitätsmedizin Berlin, the Berlin Institute of Health, and the German Center for Lung Research, Berlin (M.A.M.), and the Division of Cystic Fibrosis, Department of Pulmonary Medicine, University Medicine Essen-Ruhrlandklinik, University of Duisburg-Essen, Essen (S.S.) - all in Germany; Vall d'Hebron Barcelona Hospital Campus, Barcelona (A.A.); Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico and the University of Milan - both in Milan (C.C.); Wilhelmina Children's Hospital-University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands (K.M.W.-G.); Assistance Publique-Hôpitaux de Paris (AP-HP) Centre-Université de Paris Hôpital Cochin AP-HP, Paris (I.F.); Rainbow Babies and Children's Hospital, Cleveland (K.A.M.); St. Vincent's University Hospital, Dublin (E.F.M.); Seattle Children's Hospital, Seattle (B.W.R.); National Jewish Health, Denver (J.L.T.-C.); St. Michael's Hospital, Toronto (E.T.); Vertex Pharmaceuticals, Boston (N.A., L.S.J., S.M.M., V.P.-C., S.T., D.W., F.X., Y.Z.); the University of Alabama at Birmingham, Birmingham (S.M.R.); and the University of Kansas Medical Center, Kansas City (D.P.).