1 Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK; United Kingdom of Great Britain and Northern Ireland, UK. Electronic address: g.giovannoni@qmul.ac.uk.
2 Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK; United Kingdom of Great Britain and Northern Ireland, UK.
3 Department of Neurology, John Hunter Hospital, University Newcastle, Australia.
4 Department of Neurology, Massachusetts General Hospital and Harvard Medical School, United States.
5 Department of Pediatrics (Neurology), SickKids Research Institute, Division of Neurosciences and Mental Health, Hospital for Sick Children, University of Toronto, Canada.