1 Department of Motor Neuroscience and Movement Disorders, UCL Queen Square Institute of Neurology, London, United Kingdom.
2 Department of Neurology, University Hospital Heidelberg, Germany.
3 Department of Neurology, Charing Cross Hospital, London, United Kingdom.
4 Center for Neurodegenerative Diseases (CEMAND), Department of Medicine, Surgery and Dentistry "Scuola Medica Salernitana", University of Salerno, Baronissi (SA), Italy.
5 Department of Molecular Neuroscience, Institute of Neurology, University College London, London, United Kingdom.