1. From the Edmond J. Safra Program in Parkinson’s Disease, University Health Network, and the University of Toronto, Toronto (A.E.L.), and the Montreal Neurological Institute, Montreal (R.B.P.); the University of Pennsylvania, Philadelphia (A.D.S.); the Biostatistics Center, Massachusetts General Hospital (E.A.M.), Beth Israel Deaconess Medical Center (D.K.S.), and Harvard Medical School (E.A.M., D.K.S.), Boston, and Biogen, Cambridge (K.F., J.X., K.C.E., D.L.G., I.S., J.I., R.M.H., M.Y., S.B.H., T.D.) —...