1. Sobell Department of Movement Disorders, Institute of Neurology and University College London, London, UK
2. Department of Neuropsychiatry, BSMHFT and University of Birmingham, Birmingham, UK
3. Child Neuropsychiatry Unit, Department of Experimental Medicine, University of Insubria, Varese, Italy
4. Department of Child Neurology and Psychiatry, IRCCS 'C. Mondino' Foundation, University of Pavia, Pavia, Italy
5. Department of Neurology, Royal Free and University College Medical School, London, UK