1 Queen Square Multiple Sclerosis Centre, Department of Neuroinflammation, UCL Queen Square Institute of Neurology, Faculty of Brain Sciences, University College London, London, WC1N 5EH, UK.
2 Inherited White Matters Disorders Highly Specialised Service, National Hospital for Neurology and Neurosurgery, University College London Hospitals NHS Foundation Trust, London, WC1N 3BG, UK.
3 National Institute for Health Research, University College London Hospitals, Biomedical Research Centre, London, W1T 7DN, UK.
4 Charles Dent Metabolic Unit, University College London Hospitals NHS Foundation Trust National Hospital for Neurology and Neurosurgery, London, WC1N 3AX, UK.
5 Department of Neuromuscular Disease, UCL Queen Square Institute of Neurology, London, WC1N 3BG, UK.