1. Erasmus University Medical Centre; P.O. Box 2040 University Medical Centre Rotterdam Rotterdam Netherlands 3000 CA
2. National Hospital for Neurology and Neurosurgery; MRC Centre for Neuromuscular Diseases; PO Box 114 Queen Square London UK WC1N 3BG
3. National Hospital for Neurology and Neurosurgery; Queen Square Centre for Neuromuscular Diseases; PO Box 114 London UK WC1N 3BG
4. King's College Hospital; Department of Neurology; Denmark Hill London UK SE5 9RS
5. Charing Cross Hospital; Neuromuscular Unit 3 North; Fulham Palace Road London UK W6 8RF