1. King's College Hospital; Department of Neurology; Denmark Hill London UK SE5 9RS
2. National Hospital for Neurology and Neurosurgery; Queen Square Centre for Neuromuscular Diseases; PO Box 114 London UK WC1N 3BG
3. National Hospital for Neurology and Neurosurgery; MRC Centre for Neuromuscular Diseases; PO Box 114 London UK WC1N 3BG
4. Erasmus University Medical Center; Department of Neurology; PO Box 2040 Rotterdam Netherlands 3000 CA