Current 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.

Inclusion Criteria:

• Subjects with DMD or BMD based on genetic testing. Control subjects are unknown to have any other muscular dystrophy by history and may have had no genetic testing.
• Able to provide informed consent or assent for participation in the study.
• Demographic characteristics for biofluid collection: Males age 5 years and older with DMD or BMD; males and females ages 18 years and older without muscular dystrophy.

Exclusion Criteria:

• Medical history of any of the following: State of immunosuppression; coagulopathy; pre-existing liver or kidney disease; documented HIV positive; documented hepatitis B and/or C positive.
• Use of anti-platelet drugs within 7 days prior to blood draw; use of anticoagulants within 60 days prior to blood draw.
• Inability or unwillingness of the subject to give written informed consent.

Males ages 5 years and older with Duchenne muscular dystrophy (DMD) or Becker muscular dystrophy (BMD). In addition, male and female family members without known muscular dystrophy ages 18 and older also are invited to participate.