1 Department of Paediatrics, University of Oxford, MDUK Oxford Neuromuscular Centre & NIHR Oxford Biomedical Research Centre, Oxford, UK; Department of Paediatrics, University and University Hospital of Liège, Neuromuscular Reference Centre, Liège, Belgium. Electronic address: laurent.servais@paediatrics.ox.ac.uk.
2 Departamento de Neurologia, Faculdade de Medicina da Universidade de São Paulo (FMUSP), São Paulo, São Paulo, Brazil.