1. Department of Physical Medicine and RehabilitationUniversity of California Davis School of MedicineDavis California95817 USA
2. Department of NeurologyWashington University School of MedicineSt. Louis Missouri USA
3. Institute of Genetic MedicineNewcastle UniversityNewcastle upon Tyne UK
4. Department of Physical TherapyUniversity of Utah School of MedicineSalt Lake City Utah USA
5. Department of Physical TherapyChildren's Hospital of PhiladelphiaPhiladelphia Pennsylvania USA
6. PTC TherapeuticsSouth Plainfield NJ USA