1Departments of Neuroimmunology and The National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK
2Clinical Biochemistry and The National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK
3Neurochemistry, Institute of Neurology and The National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK