1. Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA
2. Departments of Neurology Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
3. Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, IA, USA
4. Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
5. Department of Neurology, University of California, San Diego, CA, USA
6. Department of Neurology, University Medical Center Goettingen, Goettingen, Germany and Paracelsus-Elena-Klinik, Kassel, Germany
7. The Michael J. Fox Foundation, New York, NY, USA
8. Institute for Neurodegenerative Disorders, New Haven, CT, USA
9. Department of Neurology, University of California San Francisco, San Francisco, CA, USA
10. Department of Neurology, University of Rochester Medical Center, Rochester, NY, USA