1. Department of Metabolic Diseases, Wilhelmina Children's Hospital University Medical Center Utrecht, Utrecht University Utrecht The Netherlands
2. Bartiméus Institute for the Visually Impaired Zeist, Doorn The Netherlands
3. Department of Pediatrics Amphia Hospital Breda The Netherlands
4. Department of Human Genetics Radboud University Medical Center Nijmegen The Netherlands
5. Department of Genetics University Medical Center Utrecht Utrecht The Netherlands
6. Department of Clinical Genetics Leiden University Medical Center Leiden The Netherlands