1 Institute of Clinical Medicine, University of Oslo, Oslo, Norway; Department of Pediatrics, Vestfold Hospital Trust, Tønsberg, Norway.
2 Department of Rehabilitation and Physiotherapy, Vestfold Hospital Trust, Tønsberg, Norway.
3 Norwegian National Unit for Newborn Screening, Division of Pediatric and Adolescent Medicine, Oslo University Hospital, Oslo, Norway.
4 Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology; Unit for Physiotherapy Services, Trondheim Municipality, Trondheim, Norway; Department of Physiotherapy, Oslo Metropolitan University, Oslo, Norway.