myofibrillar myopathy

Introduction

A group of morphologically homogeneous, but genetically heterogeneous chronic neuromuscular disorders

Pathology

• morphologic changes in skeletal muscle in MFM result from disintegration of the sarcomeric Z disc & the myofibrils, followed by abnormal ectopic accumulation of multiple proteins involved in the structure of the Z disc, including:
  • desmin
  • alpha-B-crystallin (CRYAB)
  • dystrophin
  • myotilin (TTID)
• polyneuropathy may coexist
• cardiomyopathy may coexist

Genetics

• associated with defects in CRYAB (type 2)

Clinical manifestations

• weakness of the proximal & distal limb muscles
• weakness of the neck, velopharynx & trunk muscles
• hypetrophic cardiomyopathy
• cataracts in a subset of patients

More general terms

• muscular disease; myopathy

More specific terms

• CRYAB-related myofibrillar myopathy; myofibrillar myopathy fatal infantile hypertonic CRYAB; myofibrillar myopathy fatal infantile hypertonic alpha-B crystallin-related
• desmin-related myofibrillar myopathy; desmin-related cardioskeletal myopathy
• ZASP-related myofibrillar myopathy

Database

• OMIM: https://mirror.omim.org/entry/601419
• OMIM: https://mirror.omim.org/entry/608810