1 Manchester Centre for Clinical Neurosciences, Salford Royal NHS Foundation Trust, Manchester, UK.
2 MRC Centre for Neuromuscular Diseases, National Hospital of Neurology and Neurosurgery, University College London Hospitals NHS Foundation Trust, London, UK.
3 Department of Dermatology, Salford Royal NHS Foundation Trust, Manchester, UK.
4 Department of Cellular Pathology, Salford Royal NHS Foundation Trust, Manchester, UK.