1. Dubowitz Neuromuscular Centre, UCL Great Ormond Street Institute of Child Health , London WC1N 1EH , UK
2. Queen Square Centre for Neuromuscular Diseases, University College London , London WC1N 3BG , UK
3. Population, Policy and Practice Research and Teaching Department, UCL Great Ormond Street Institute of Child Health , London WC1N 1EH , UK
4. NIHR Great Ormond Street Hospital Biomedical Research Centre, UCL Great Ormond Street Institute of Child Health , London WC1N 1EH , UK
5. Division of Psychological Medicine and Clinical Neurosciences, School of Medicine, Cardiff University , Cardiff CF14 4XN , UK
6. Department of Clinical, Educational and Health Psychology, University College London , London WC1E 6BT , UK
7. Department of Behavioural and Brain Sciences, UCL Great Ormond Street Institute of Child Health , London WC1N 1EH , UK