1 Paediatric Neurology, Great North Children's Hospital, Newcastle upon Tyne, NE1 4LP, United Kingdom. Electronic address: katy.wood4@nhs.net.
2 Clinical Genetics, Institute of Human Genetics, International Centre for Life, Newcastle upon Tyne, NE1 4LP, United Kingdom. Electronic address: t.montgomery@nhs.net.
3 Paediatric Neurology, Great North Children's Hospital, Newcastle upon Tyne, NE1 4LP, United Kingdom; Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom. Electronic address: anita.devlin@nhs.net.