Author information:
(1)Departments of Neurology, Massachusetts General Hospital, Boston, 
Massachusetts, USA.
(2)University of South Florida Epidemiology Center, Tampa, Florida, USA.
(3)MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, London, 
UK.
(4)Departments of Neurology, IRCCS Foundation, Carlo Besta Neurological 
Institute, Milan, Italy.
(5)Departments of Neurology, University of Iowa Hospitals and Clinics, Iowa 
City, Iowa, USA.
(6)Departments of Neurology, University of Sydney & Children's Hospital, Sydney, 
Australia.
(7)Departments of Neurology, Stanford University, Stanford, California, USA.
(8)Departments of Neurology, University of Iowa Hospitals and Clinics, Iowa 
City, Iowa, USA Departments of Neurology, Wayne State University, Detroit, 
Michigan, USA.
(9)Departments of Neurology, Nemours Children's Hospital, Orlando, Florida, USA.
(10)Departments of Neurology, University of Rochester, Rochester, New York, USA.
(11)Departments of Neurology, Vanderbilt University, Nashville, Tennessee, USA.
(12)Departments of Neurology, John Hopkins University, Baltimore, Maryland, USA.
(13)Departments of Neurology, UCL Institute of Child Health & Great Ormond 
Street Hospital, London, UK.
(14)Departments of Neurology, Wayne State University, Detroit, Michigan, USA 
Departments of Neurology, University of Michigan, Ann Arbor, Michigan, USA.
(15)Departments of Neurology, Children's Hospital of Philadelphia, Philadelphia, 
Pennsylvania, USA Departments of Neurology, Hospital of the University of 
Pennsylvania, Philadelphia, Pennsylvania, USA.
(16)Departments of Neurology, Center for Human Molecular Genomics, University of 
Miami, Miami, Florida, USA.
(17)Departments of Neurology, Hospital of the University of Pennsylvania, 
Philadelphia, Pennsylvania, USA.