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Establishing Biomarkers and Clinical Endpoints in Myotonic Dystrophy Type 1 (END-DM1)


Brief Summary

Building on previous work of the Myotonic Dystrophy Clinical Research Network (DMCRN), the present study seeks to overcome insufficient data on natural history; lack of reliable biomarkers; and incomplete characterization and limited biological understanding of the phenotypic heterogeneity of Myotonic Dystrophy 1 by examining strategies to improve the reliability by making further refinements in our sample collection and analysis procedures by developing strategies for managing patient heterogeneity going forward.

Study Type


Healthy Volunteers
Minimum Age
18 Years
Maximum Age
70 Years

Inclusion criteria:

  • Age 18 to 70 (inclusive)
  • Competent to provide informed consent
  • Clinical diagnosis of DM1 based on research criteria1 or positive genetic test
  • Comment: The clinical research criteria require myotonia, muscle weakness in a characteristic distribution, and history of similar findings in a first degree relative. Genetic testing confirmed the diagnosis of DM1 in > 99% of individuals who satisfied these criteria.2

Exclusion criteria:

  • Symptomatic renal or liver disease, uncontrolled diabetes or thyroid disorder, or active malignancy other than skin cancer.
  • Current alcohol or substance abuse
  • Concurrent enrollment in clinical trial for DM1, or participation in trial within 6 months of entry.
  • Concurrent pregnancy or planned pregnancy during the course of the study.
  • Concurrent medical condition that would, in the opinion of the investigator or clinical evaluator, compromise performance on study measures.
  • Note: non-ambulatory participants are not excluded, but are limited to <15% of enrollment.

Inclusion criteria for participants in the muscle biopsy sub-study:

  • Of the 95 patients undergoing the tibialis anterior muscle biopsy, at least half will have at least moderate weakness of ankle dorsiflexion, defined as MRC score ≤ 4+. This is in order to obtain a muscle tissue sample in a person more severely affected with myotonic dystrophy. Approximately 10 patients at each site will undergo the muscle biopsy.

Exclusion criteria for 95 participants in the muscle biopsy sub-study:

  • Known CTG repeat expansion size less than 100 repeats, unless there are clear cut signs of limb weakness and muscle wasting. This is in order to obtain a muscle tissue sample in a person more severely affected with myotonic dystrophy.
  • Use of anticoagulant such as warfarin or a direct oral anticoagulant (e.g. dabigatran) due to the increased risk of bleeding.
  • Use of aspirin or non-steroidal anti-inflammatory agents should be discontinued 3 days prior to the biopsy procedure, if possible.
  • Platelet count <50,000 (if known) due to the increased risk of bleeding.
  • History of a bleeding disorder due to the increased risk of bleeding.
  • Advanced wasting of tibialis anterior (TA) muscle that precludes needle muscle biopsy in order to ensure that a sample taken would be of muscle and not just fat and fascia.
  • Previous muscle biopsy of either TA in order to provide muscle tissue samples of non-biopsied muscles.

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Study Stats
Protocol No.
Jennifer Huynh
  • UCLA Westwood
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