RecruitingExtracellular RNA Biomarkers of Duchenne Muscular DystrophyCurrent methods of measuring the response to new treatments for muscular dystrophies involve the examination of small pieces of muscle tissue called biopsies. The investigators are interested in finding less invasive methods that reduce the need for muscle biopsies. The purpose of this research is to learn about the possibility of detecting and measuring the activity and severity of muscular dystrophies by examining a urine sample and a blood sample.