1. Division of Pediatric Neurology, David Geffen School of Medicine, Mattel Children's Hospital at UCLA, Los Angeles, CA
2. Division of Pediatric Neurology, Boston University School of Medicine, Boston, MA
3. Division of Neuroepidemiology, Harvard Medical School, Harvard School of Public Health, Department of Neurology, Children's Hospital, Boston, MA
4. Neuromuscular Program, Children's Hospital Boston, Boston, MA, Department of Orthopedics, Harvard Medical School, Boston, MA
5. Neuromuscular Program, Children's Hospital Boston, Boston, MA , Department of Neurology, Harvard Medical School