1. Department of Physical Medicine and RehabilitationNeuromuscular Medicine and Rehabilitation Research Center, University of California Davis School of MedicineDavis California95817 USA
2. Department of NeurologyWashington University School of MedicineSt. Louis Missouri USA
3. Institute of Genetic Medicine, Newcastle 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 Therapeutics, South Plainfield New Jersey USA