1. Veterans Affairs Puget Sound Health Care System, Seattle, WA, USA
2. Department of Neurology, University of Washington, Seattle, WA, USA
3. Department of Rehabilitation Medicine, University of Washington, Seattle, WA, USA
4. Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA
5. Lerner Research Institute, Genomic Medicine, Cleveland Clinic, Cleveland, OH, USA