1. MRC Centre for Neuromuscular Diseases, Institute of Genetic Medicine; Newcastle University, Central Parkway Newcastle upon Tyne NE1 3 BZ; United Kingdom
2. Neuromuscular Disorders Unit; Neurology Department, Hospital Donostia; San Sebastián Spain
3. Neuroscience Area; Biodonostia Health Research Institute; San Sebastián Spain
4. Center for Biomedical Research in the Neurodegenerative Diseases (CIBERNED) Network; Instituto Carlos III, Ministry of Economy and Competitiviness; Madrid Spain
5. UCL MRC Centre for Neuromuscular Diseases, Institute of Neurology; London United Kingdom
6. Department of Clinical Neurology; John Radcliffe Hospital; Oxford United Kingdom
7. Department of Neurology; King's College Hospital; London United Kingdom
8. The Robert Jones and Agnes Hunt Orthopaedic Hospital; Oswestry United Kingdom
9. Institute of Medical Genetics; University Hospital of Wales; Cardiff United Kingdom
10. Wessex Neurological Centre; University Hospital of Southampton; Southampton United Kingdom
11. Department of Neurology; Salford Royal NHS Foundation Trust; Salford United Kingdom
12. Department of Neurology; Derriford Hospital, Plymouth Hospitals NHS Trust; Plymouth United Kingdom
13. Bristol Genetics Laboratory, Southmead Hospital, North Bristol NHS Trust; Bristol United Kingdom