Cerebrospinal Fluid Biomarkers of Myotonic Dystrophy

Inclusion Criteria: * Subjects with DM1 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). * Unaffected subjects are unknown to have myotonic dystropphy or any other muscular dystrophy by history and may have had no genetic testing. * Clinical indicators of current status, as measured within 30 days of study start: Able to provide informed consent or assent for participation in the study. * Demographic characteristics (e.g., biologic sex, age): Males and females age 18 years and older. Exclusion Criteria: * Medical history of any of the following. State of immunosuppression; pre-existing liver or kidney disease; documented HIV positive; documented hepatitis B and/or C positive. * Medications and other drugs. Use of anticoagulants within 60 days prior to lumbar puncture and/or blood draw. Use of anti-platelet drugs within 7 days prior to blood draw. * Contraindications to MRI. The presence of any metal within the body, which would include any medical device containing metal, such as a pacemaker, defibrillator, some heart valves or stents, artificial joint, aneurysm clip, or inner ear device, a history of working with sheet metal, or an injury with metal shrapnel; pregnancy, due to effects of MRI on unborn children. * Contraindications to Lumbar Puncture. Evidence of increased intracranial pressure or active infection on exam; platelets less than 50,000. * Other. Inability or unwillingness of the subject to give written informed consent.