From the John Walton Muscular Dystrophy Research Centre (M. Schiava, A.T., V.S., M.G., C.M.-B., J.D.-M.), Institute of Genetic Medicine, Centre for Life, Newcastle University and Newcastle Hospitals NHS Foundation Trusts, Newcastle Upon Tyne, United Kingdom; Johns Hopkins University School of Medicine (C. Ikenaga), Baltimore, MD; Unidad de Enfermedades Neuromusculares (M.C.-Á.), Servicio de Neurología, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain; Division of Biology and Biological Engineering (T.-F.C., S.L., F.W.), California Institute of Technology, Pasadena; Department of Neurology (J.D.), Washington University School of Medicine, St. Louis, MO; APHP Centre de référence des maladies neuromusculaires Institut de Myologie Sorbonne Université APHP Hôpital Pitié-Salpêtrière Paris (T.S., R.V.-Q.), France; Department of Neuromuscular Research (I.N., M.I., Y.N., Y.S.), National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP); Departments of Neurology (M.K., S. Noda) and Clinical Research Education (M.K., S. Noda), Nagoya University Graduate School of Medicine; Department of Neurology (M.K., S. Noda), National Hospital Organization Suzuka Hospital; Department of Neurology (C. Ito), Aichi Medical University School of Medicine; Department of Neurology (M.O.), International University of Health and Welfare Hospital, Japan; Department of Neurology Sree Chitra Tirunal Institute for Medical Sciences and Technology (S. Nahir), Thiruvananthapuram, Kerala, India; Department of Neurology (G.M., D.W.), University of Minnesota, Minneapolis; Department of Neurology (C.Q.), University of Pennsylvania, Perelman School of Medicine, Philadelphia; Center for Gene Therapy (L.A., Z.S.), The Abigail Wexner Research Institute at Nationwide Children's Hospital; Department of Pediatrics (L.A., Z.S.), The Ohio State University College of Medicine, Columbus; Unità Operativa Complessa di Neurologia Fondazione Policlinico Universitario A Gemelli IRCCS (G.T., M.M.); Centro clinico NEMO- Fondazione policlinico universitario A. Gemelli IRCCS (M. Sabatelli, G.B.), Rome, Italy; Department of Laboratory Medicine, Institute of Biomedicine, University of Gothenburg (A.O.); Department of Neurology (A.R.), Clinical Sciences Lund, Lund University, Sweden; Departments of Neurology and Neuropathology (E.P.), University of Pécs, Hungary; Neurology Department, Neuromuscular Disorders Unit, Hospital Universitario Virgen del Rocío (C.P., B.V.); Instituto de Biomedicina de Sevilla (C.P.); Centre for Biomedical Network Research on Neurodegenerative Disorders (CIBERNED) Instituto de Salud Carlos III (C.P., B.V.), Madrid, Spain; Neurology Department and Neuromuscular Reference Centre (J.L.D.B.), Gent, Blegium, part of the ERN NMD; Institute of Neurological Sciences (M.E.F.); West Scotland Regional Genetics Service (C.L.), Queen Elizabeth University Hospital, Glasgow, United Kingdom; Columbia University Irving Medical Centre (M.B.H.), New York; Centre for Genomic and Experimental Medicine (S.R.), Institute of Genetics and Cancer, University of Edinburgh, Western General Hospital Edinburgh, United Kingdom; Department of Neurology (E.Z., A.M.S.S.), School of Medicine, Universidade de São Paulo (FMUSP), Brazil; Neurology Service (J.S., R.J.-M.), Neuromuscular Disorders Unit, Hospital Universitari Vall d'Hebron, Barcelona, Spain; Departamento de Neurología y Neurocirugía (J.B.), HCUCH, Departamento de Anatomía y Medicina Legal, Facultad de Medicina, Universidad de Chile; Departamento de Neurología y Neurocirugía Clínica (M.B.), Clínica Dávila, Santiago Chile; Newcastle University (S.T.), Newcastle Upon Tyne, United Kingdom; and Department of Neurology (C.C.W.), Washington University School of Medicine, Saint Louis, MO.