1 MDUK Oxford Neuromuscular Centre, Department of Paediatrics, University of Oxford, UK; Department of Paediatric Neurology, John Radcliffe Hospital, Oxford, UK.
2 MDUK Oxford Neuromuscular Centre, Department of Paediatrics, & NIHR Oxford Biomedical Research Centre, University of Oxford, UK; Neuromuscular Centre, Division of Paediatrics, University and University Hospital of Liège, Belgium. Electronic address: laurent.servais@paediatrics.ox.ac.uk.