1. Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Centre, Nijmegen, The Netherlands
2. Department of Neurology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
3. Department of Neurology, University Medical Centre Utrecht, The Netherlands
4. Department of Genetics, Radboud University Medical Centre, Nijmegen, The Netherlands
5. Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, UK
6. Institute de Myologie, Paris, France