1. Demyelinating Disorders Program, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
2. Department of Pediatrics (Neurology), University of Toronto, Toronto, ON, Canada
3. Pediatric Multiple Sclerosis Center and Baird Multiple Sclerosis Center, Jacobs Neurological Institute, State University of New York at Buffalo, Buffalo, NY, USA
4. Department of Neurology, State University of New York at Buffalo, Buffalo, NY, USA