What is Myopathic Ehlers-Danlos (mEDS)?

Myopathic EDS (mEDS) is characterized by muscle weakness that manifests in childhood with proximal contractures of the large joints and distal joint hypermobility. Typically, muscle weakness improves in young adulthood, although it may deteriorate again in the fourth decade of life. The spectrum of disorders characterized by muscle weakness, hypotonia, myopathy, and connective tissue symptomatology was originally associated with collagen type VI disorders.

Pathogenic variants in COL12A1, which encodes the α1-chain of type XII collagen, are the molecular cause of mEDS. Collagen XII is present as a homotrimer on the surface of type I collagen fibers. It forms a link between type I collagen fibers and extracellular matrix components such as decorin, fibromodulin, and tenascin. To date, mEDS has been described in both an autosomal dominantly inherited form with heterozygous missense variants and an autosomal recessively inherited form with homozygous frameshift variants.

Source: [1 Medicover Genetics l Ehlers Danlos Syndrome, Myopathic (mEDS)]

Signs & Symptoms of Myopathic EDS

Individuals with Myopathic EDS may have the following features:

  • Muscle weakness
  • Contractures of the large joints
  • Distal joint hypermobility
  • Hypotonia – low muscle tone
  • Myopathy including muscle cramps, stiffness and spasms

Source: [1 Ehlers Danlos Society]

Diagnosis of Myopathy Ehlers-Danlos Syndrome

There are four minor criteria. The minimal criteria required to suggest a diagnosis of mEDS are the first major criterion plus either: one other major criterion, or three minor criteria.

Major Criteria

  1. Congenital muscle hypotonia, and/or muscle atrophy, that improves with age
  2. Proximal joint contractures (knee, hip, and elbow)
  3. Hypermobility of distal joints

Minor Criteria

  1. Soft, doughy skin
  2. Atrophic scarring
  3. Motor developmental delay
  4. Myopathy on muscle biopsy

A final diagnosis requires confirmation by molecular testing.

Sources: [1 Ehlers-Danlos Society] [2 2017 International Classification of the Ehlers-Danlos Syndromes]

Support for Arthrochalasia Ehlers-Danlos Syndrome

Please feel free to join our Nationwide Support Group “Loosely Speaking” on Facebook, or check out our more localised support groups to see if there is one within your area.

EDSNZ are working at compiling a list of resources of services and support you may be interested in. Among these are: