1. ; Biochemistry, Endocrinology and Metabolism Unit, Institute of Child Health; University College London and Great Ormond Street Hospital for Children NHS Trust; London UK
2. ; Biochemistry, Endocrinology and Metabolism Unit, Institute of Child Health (; University College London); 30 Guilford Street London WC1N 1EH UK
3. ; Department of Paediatric Neurology; University Medical Centre St Radboud; Nijmegen The Netherlands
4. ; Department of Human Genetics; University Medical Centre St Radboud; Nijmegen The Netherlands
5. ; Department of Child Health; King's College Hospital; London UK
6. ; Department of Neurology; University Medical Centre St Radboud; Nijmegen The Netherlands