1. Department of Paediatrics, MDUK Oxford Neuromuscular Centre and, NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford OX1 3DW, UK
2. Centre de Référence des Maladies Neuromusculaires, Department of Neurology, University Hospital Liège, and University of Liège, 4000 Liège, Belgium
3. Centre de Référence des Maladies Neuromusculaires, Department of Paediatrics, University Hospital Liège, and University of Liège, 4000 Liège, Belgium