1. Department of Neurology, School of Medicine, Johns Hopkins University, Baltimore, MD, USA,
2. Neurology Clinical Research Institute, Massachusetts General Hospital, Boston, MA, USA,
3. Department of Physical Medicine and Rehabilitation, Harvard University, Boston, MA, USA,
4. Carolinas Neuromuscular/ALS-MDA Center, Department of Neurology, Neuroscience and Spine Institute, Carolinas HealthCare System, Charlotte, NC, USA, and
5. Department of Neurology, Cedars-Sinai Medical Center, Los Angeles, CA, USA