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Myofibrillar myopathies

Kristl G Claeys1, Michel Fardeau

  • 1Department of Neurology and Institute for Neuropathology, University Hospital RWTH Aachen, Aachen, Germany.

Handbook of Clinical Neurology
|April 30, 2013
PubMed

Insights

Myofibrillar myopathies (MFMs) are rare genetic neuromuscular disorders. Understanding the genetic causes and clinical features of MFMs is crucial for diagnosis and management.

Area of Science:

  • Neuromuscular Disorders
  • Genetics
  • Molecular Biology

Background:

  • Myofibrillar myopathies (MFMs) are a heterogeneous group of inherited or sporadic neuromuscular diseases.
  • MFMs are characterized by myofibril dissolution starting at the Z-disk and accumulation of degradation products.
  • Mutations in six genes encoding sarcomeric Z-disk proteins are known to cause MFMs, accounting for about 50% of cases.

Purpose of the Study:

  • To review the clinical and genetic heterogeneity of myofibrillar myopathies.
  • To highlight the known genetic causes and their associated clinical manifestations.
  • To emphasize the importance of careful follow-up for cardiac and respiratory function in MFM patients.

Main Methods:

  • Review of existing literature on myofibrillar myopathies.
  • Analysis of clinical presentations and genetic findings in MFM patients.
  • Comparison of diagnostic features, including optical microscopy and immunohistochemistry.

Main Results:

  • Six genes (desmin, αB-crystallin, myotilin, ZASP, filamin C, Bag3) are identified as causative for MFMs.
  • Clinical heterogeneity includes adult-onset slow progression and infantile/juvenile onset with severe cardiac/respiratory involvement (e.g., Bag3opathies).
  • Cardiac involvement is common in desminopathies; respiratory symptoms in childhood occur in αB-crystallinopathies.

Conclusions:

  • MFMs exhibit significant clinical and genetic diversity.
  • While optical microscopy and immunohistochemistry show similarities, ultrastructural findings aid in subtype differentiation.
  • Currently, no cure exists, necessitating diligent monitoring of cardiac and respiratory functions.

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