1. Department of Neurology, Columbia University Irving Medical Center, New York, NY 10032, USA
2. Department of Rehabilitation and Regenerative Medicine, Columbia University Irving Medical Center, New York, NY 10032, USA
3. Department of Biobehavioral Sciences, Teachers College, Columbia University, New York, NY 10115, USA
4. Department of Epidemiology, School of Public Health, University of Pittsburgh, Pittsburgh, PA 15213, USA
5. Pediatric Neurology Unit, Catholic University, 00135 Rome, Italy
6. Centro Clinico Nemo, U.O.C. Neuropsichiatria Infantile Fondazione Policlinico Universitario Agostino Gemelli IRCCS, 00168 Rome, Italy
7. Department of Neurology and Clinical Neurosciences, Stanford University School of Medicine, Palo Alto, CA 94305, USA
8. Dubowitz Neuromuscular Centre, UCL Great Ormond Street Institute of Child Health, London WC1N 1EH, UK
9. The John Walton Muscular Dystrophy Research Centre, Translational and Clinical Research Institute, Newcastle University and Newcastle Hospitals NHS Foundation Trust, Newcastle upon Tyne NE1 7RU, UK