1. Neuromuscular Reference CentreUniversity Hospital St Luc, University of Louvain, Avenue Hippocrate 10 Brussels Belgium
2. Department of Neurology, Erasmus MCUniversity Medical Center Rotterdam Wytemaweg 80 CN, Rotterdam The Netherlands
3. Department of Neurology and Immunology, Erasmus MCUniversity Medical Center Rotterdam Wytemaweg 80 CN, Rotterdam The Netherlands
4. Neuromuscular Diseases Unit, Department of Neurology, Hospital de la Santa Creu i Sant PauUniversitat Autònoma de Barcelona, Mas Casanovas 90 Barcelona Spain
5. Department of NeurologyJohns Hopkins University School of Medicine Meyer 6‐181a North, Wolfe Street, Baltimore US