1. Unit for Inborn and Hereditary Neuromuscular Disorders, Department of Neurology Oslo University Hospital Oslo Norway
2. National Neuromuscular Centre Norway University Hospital of North Norway Tromsø Norway
3. Vikersund Rehabilitation Centre Vikersund Norway
4. Frambu Resource Centre for Rare Disorders Siggerud Norway
5. Department of Neurology, Amsterdam University Medical Centre Location University of Amsterdam Amsterdam The Netherlands