Biomarker Development for Muscular Dystrophies

Inclusion Criteria: * Subjects with DM1 or DM2 based on genetic testing and/or clinical criteria (some subjects who have positive genetic testing may be asymptomatic, while other subjects who show characteristic clinical features may have declined to have genetic testing done). Control non-DM subjects are unknown to have DM or 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 single biofluid collection: Males and females age 5 years and older. * Demographic characteristics for serial biofluid and muscle function testing: Males and females age 14 years and older with DM1. * Demographic characteristics for biofluid and muscle biopsy: Males and females, ages 18-65 years. Demographic characteristics for single biofluid collection, ultrasound, and myography: Males and females age 14 years and older. 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. * Medications and other drugs. Use of anti-platelet drugs within 7 days prior to blood draw or biopsy; use of anticoagulants within 60 days prior to blood draw or biopsy; active drug or alcohol use or dependence that, in the opinion of the biopsy surgeon, would interfere with post-procedure wound care. * Other. Inability or unwillingness of the subject to give written informed consent.