A Study to Assess if BIIB122 Tablets Are Safe and Can Slow Worsening of Early-Stage Parkinson's Disease in Participants With Specific LRRK2 Genetic Variants Between the Ages of 30 and 80 Using the Movement Disorder Society-Unified Parkinson's Disease Rating Scale

Universitaetsklinikum Carl Gustav Carus TU Dresden, Dresden

Hospital Universitari Vall d'Hebron, Barcelona

Hospital Clinic de Barcelona, Barcelona

Hospital General de Catalunya, Sant Cugat del Vallès

Mount Sinai Beth Israel, New York

Weill Medical College of Cornell University, New York

Hôpital de la Timone, Marseille

Pennsylvania Hospital, Philadelphia

Hospital Universitario Donostia, Donostia / San Sebastian

Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan

Hopital Purpan, Toulouse

Parkinson's Disease and Movement Disorders Center, Boca Raton

USF Health Byrd Institute, Tampa

CHU Rennes - Hopital Pontchaillou, Rennes

Hospital Universitario Marques de Valdecilla, Santander

Hospital Universitario Virgen del Rocio, Seville

University of Kansas Medical Center Research Institute, Inc., Kansas City

Centre Hospitalier Universitaire de Lyon-Hospices Civils de Lyon-Hopital Pierre Wertheimer, Bron

Universitaetsklinikum Tuebingen, Tübingen

Groupe Hospitalier Pitie-Salpetriere, Paris

University of Colorado, Aurora

Rocky Mountain Movement Disorders Center, PC, Englewood

University of California San Francisco (UCSF), San Francisco

Evergreen Hospital Medical Center, Kirkland

Inland Northwest Research, Spokane

Massachusetts General Hospital, Boston

Ninewells Hospital, Dundee