1. Muscle Research Unit, Internal Medicine Service, Hospital Clínic de Barcelona, Universidad de Barcelona and CIBERER , Barcelona, Spain
2. Muscle Disease Unit, Laboratory of Muscle Stem Cells and Gene Regulations, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health , Bethesda, Maryland, USA
3. Department of Neurology, Johns Hopkins University School of Medicine , Baltimore, MD, USA
4. Department of Medicine, Johns Hopkins University School of Medicine , Baltimore, MD, USA