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Reducing body myopathy associated with the LIM2 p.(His123Arg) FHL1 variant

Leila Darki1, Arash Jalali-Sohi1, Samuel Guzman2

  • 1Neuromuscular Division, Department of Neurology of the University of Southern California Keck School of Medicine, Los Angeles, CA, United States.

Clinical Neurology and Neurosurgery
|July 17, 2021
PubMed

Insights

Reducing body myopathy (RBM) is a rare genetic muscle disorder. This case highlights a pathogenic FHL1 gene variant causing progressive muscle weakness and contractures in a young female.

Area of Science:

  • Neurology
  • Genetics
  • Muscle Biology

Background:

  • Reducing body myopathy (RBM) is a rare neuromuscular disorder characterized by specific protein aggregates within muscle fibers.
  • Mutations in the FHL1 gene are a known cause of RBM, presenting with variable clinical severity.
  • The spectrum of RBM ranges from severe infantile forms to adult-onset progressive muscle weakness.

Observation:

  • A 17-year-old female presented with progressive muscle weakness and contractures.
  • Muscle biopsy revealed atrophic muscle fibers containing characteristic menadione nitroblue tetrazolium (NBT)-positive reducing bodies.
  • Electrophysiological studies supported a myopathic process.

Findings:

  • Genetic analysis identified a variant in the FHL1 gene (p.His123Arg).
  • Initially classified as a variant of uncertain significance, this FHL1 variant was subsequently reclassified as pathogenic.
  • This pathogenic variant is located at a known mutation hotspot for RBM.

Implications:

  • This case expands the understanding of FHL1-associated RBM phenotypes.
  • Accurate genetic classification is crucial for diagnosing and managing rare myopathies.
  • Further research into FHL1 variants may elucidate genotype-phenotype correlations in RBM.
Keywords:
FHL1Muscle weaknessMyopathyRBMReducing body

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