1. Parkinson's Disease and Movement Disorders Unit, Neurology Service, Hospital Clinic de Barcelona, Universitat de Barcelona, Institut d'Investigacions Biomediques August Pi I Sunyer (IDIBAPS), Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED); Barcelona Spain
2. Neurology Unit, Hospital General de Granollers, Universitat Internacional de Catalunya; Granollers Spain
3. Department of Biostatistics, College of Public Health; University of Iowa; Iowa City Iowa USA
4. Department of Neurology; College of Physicians and Surgeons, Columbia University; New York New York USA
5. Departments of Neurology and Neurobiology; Xuanwu Hospital of Capital Medical University; Beijing China
6. Parkinson's Disease Research; Education and Clinical Center, Michael J. Crescenz VA Medical Center and Department of Neurology, Perelman School of Medicine, University of Pennsylvania; Philadelphia Pennsylvania USA
7. The Michael J. Fox Foundation for Parkinson's Research; New York New York USA
8. Laboratory of Neurodegenerative Disorders; Department of Neurology, Hospital Clínic of Barcelona, Institutd'InvestigacionsBiomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona, and the Centre for Networked Biomedical Research on Neurodegenerative Diseases (CIBERNED); Madrid Spain
9. Institute for Neurodegenerative Disorders and Molecular NeuroImaging; New Haven Connecticut USA
10. Department of Nuclear Medicine; Hospital Clinic de Barcelona, Universitat de Barcelona, Institut d'Investigacions Biomediques August Pi I Sunyer (IDIBAPS); Barcelona Spain
11. Toronto Western Hospital Morton and Gloria Shulman Movement Disorders Centre and the Edmond J. Safra Program in Parkinson's Disease; University of Toronto, Toronto; Ontario Canada
12. Department of Neurology; Movement Disorders Unit. Hospital Universitario Donostia. Biodonostia Research Institute, Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED); San Sebastián Guipúzcoa Spain
13. Department of Neurology; Mount Sinai Beth Israel Medical Center and Icahn School of Medicine at Mount Sinai; New York New York USA
14. Department of Neurology; Norwegian University of Science and Technology; Trondheim Norway