Myopathy

Description

  • Myopathy is a general term that refers to any disease that affects the muscles that control voluntary movement in the body. Myopathies can be inherited or acquired, and are a heterogeneous group of disorders that can affect muscle function due to differences in muscle structure, metabolism, or channel function. Over 200 genetic causes of myopathies have been identified, and genetic testing is indicated for all patients with myopathy of unknown cause, regardless of family history.

How often is a hereditary cause identified?

  • Diagnostic yield varies greatly across studies, with a range between 30-50%.

How does identifying a hereditary cause change a patient’s medical management?

  • Approved treatments are available for certain genetic muscle disorders, including Duchenne muscular dystrophy (DMD) and Pompe disease.

  • There are ongoing clinical trials of novel targeted therapies for several genetic myopathies (including Duchenne and Becker muscular dystrophies, Pompe disease, facioscapulohumeral muscular dystrophy, limb girdle muscular dystrophy, myotonic dystrophy, myotubular myopathy, and GNE-associated myopathy).

  • If a genetic cause is identified, this can provide information for family planning as well as information to understand the risk to family members.

How is this condition inherited?

  • Known monogenic causes of inherited myopathy have varying inheritance pattern depending on the gene (e.g. autosomal dominant, autosomal recessive).

Where can I learn more about myopathy?

References

  • Dratch L, Azage M, Baldwin A, Johnson K, Paul RA, Bardakjian TM, Michon SC, Amado DA, Baer M, Deik AF, Elman LB, Gonzalez-Alegre P, Guo MH, Hamedani AG, Irwin DJ, Lasker A, Orthmann-Murphy J, Quinn C, Tropea TF, Scherer SS, Ellis CA. Genetic testing in adults with neurologic disorders: indications, approach, and clinical impacts. J Neurol. 2023 Oct 27. doi: 10.1007/s00415-023-12058-6. Epub ahead of print. PMID: 37891417.