[1] Salford Royal NHS Fdn Trust, Manchester Ctr Clin Neurosci, Manchester, Lancs, England
[2] Univ Coll London Hosp NHS Fdn Trust, Natl Hosp Neurol & Neurosurg, MRC Ctr Neuromuscular Dis, London, England
[3] Salford Royal NHS Fdn Trust, Dept Dermatol, Manchester, Lancs, England
[4] Salford Royal NHS Fdn Trust, Dept Cellular Pathol, Manchester, Lancs, England