1. Department of Speech & Language Therapy, Aberdeen Royal Infirmary, Aberdeen, Scotland, UK
2. DART – Centre for Augmentative & Alternative Communication & Assistive Technology Regional Rehabilitation Centre, Queen Silvia Children’s Hospital, Sahlgrenska University Hospital, Gothenburg, Sweden
3. Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands
4. Department of Speech & Language Therapy, Huntington Centre, Topaz, Overduin, Katwijk, The Netherlands
5. Department of Speech & Language Therapy, Royal Hospital for Neurodisability, Putney, London, UK
6. Department of Clinical Genetics, NHS Grampian, Aberdeen, Scotland, UK
7. University of Aberdeen, Aberdeen, AB25 2ZA Scotland, UK
8. Department of Clinical Genetics, NHS Grampian, Aberdeen, Scotland, UK.