From the Providence Multiple Sclerosis Center (L.V.), Providence Brain and Spine Institute, Portland, OR; Departments of Neurology and Neurological Sciences (J.M., A.T., C.L., G.D., M.H.H.), and Epidemiology and Population Health (J.H., L.M.N.), Stanford University School of Medicine; Sparta Science (J.H.), Menlo Park, CA; Department of Pediatrics (C.P., L.J.C.), Data Coordinating Center, University of Utah School of Medicine, Salt Lake City; Department of Medicine (M.R.Y.), Geffen School of Medicine, University of California, Los Angeles; Division of Molecular Medicine (M.R.Y.), and The Lundquist Institute for Infection & Immunity, Harbor-UCLA Medical Center (M.R.Y.), Torrance, CA; and Department of Neurology (M.B.), Creighton University School of Medicine, Omaha, NE.