1 Department of Paediatric Neurology, Bristol Royal Hospital for Children, Bristol, UK.
2 Department of Paediatric Neurology, Bristol Royal Hospital for Children, Bristol, UK; Bristol Medical School, University of Bristol, Bristol, UK.
3 Institute of Child Health, University College, London, UK; Great Ormond Street Hospital, London, UK.
4 Department of Paediatric Neurology, Bristol Royal Hospital for Children, Bristol, UK; Bristol Medical School, University of Bristol, Bristol, UK. Electronic address: andrew.lux@bristol.ac.uk.