From the Dubowitz Neuromuscular Centre (F.T., M.S., M.L.M., F.M.) and Population, Policy and Practice Programme (D.R.), UCL GOS Institute of Child Health, London, UK; DINOGMI, University of Genoa (F.T.), IRCCS Istituto G. Gaslini, Italy; NIHR Great Ormond Street Hospital Biomedical Research Centre (D.R., F.M.), Great Ormond Street Institute of Child Health, University College London, and Great Ormond Street Hospital Trust, UK; Paediatric Neurology (G.C., M.P., E.M.), Catholic University; Centro Clinico Nemo (G.C., M.P., E.M.), Fondazione Policlinico Universitario Agostino Gemelli IRCSS, Rome, Italy; John Walton Muscular Dystrophy Research Centre (R.M.L., C.M.-B.), Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle Upon Tyne, UK; Departments of Neurology and Pediatrics (J.M., D.C.D.V.) and Departments of Rehabilitation and Regenerative Medicine (J.M.), Columbia University Irving Medical Center, New York, NY; Paediatric Neurology and Centro Clinico Nemo (V.S., E.A.), Milan; Unit of Neuromuscular and Neurodegenerative Disorders (A.D., E.B.), Post-Graduate Bambino Gesù Children's Research Hospital, IRCCS, Rome; Department of Clinical and Experimental Medicine (S.M.), University of Messina Paediatric Neurology and Nemo Sud Clinical Centre; Center of Translational and Experimental Myology (C.B.), IRCCS Istituto Giannina Gaslini, Genova, Italy; University Hospitals Birmingham NHSFT (D.P.); Leeds Children Hospital (A.-M.C.); Evelina Children's Hospital (V.G.), London; The Robert Jones and Agnes Hunt Orthopaedic Hospital (T.W.), Oswestry; Sheffield Children's Hospital (M.O.), UK; Department of Neurology (B.T.D.), Boston Children's Hospital and Harvard Medical School, MA; Stanford University (J.D.), Medical Centre, Palo Alto, CA; Divisions of Pediatric Neurology (E.A.K.), Pulmonology (O.H.M.) and Physical Therapy (A.M.G.), The Children's Hospital of Philadelphia, and the Perelman School of Medicine at the University of Pennsylvania, Philadelphia; and Divisions of Neurology (R.S.F.) and Pulmonary Medicine (A.A.N.N.), Department of Pediatrics, Nemours Children's Hospital, Orlando, FL.