Comparison of muscle ultrastructure in myasthenia gravis with anti-MuSK and anti-AChR antibodies

Giovanna Cenacchi, Papa Valentina, Fanin Marina, Pegoraro Elena, Angelini Corrado

Research output: Contribution to journalArticle

Abstract

Patients with myasthenia gravis (MG) with antibodies to muscle-specific receptor tyrosine kinase (MuSK) differ from acetylcholine receptor (AChR)-positive MG patients, as they frequently present with severe oculobulbar muscle weakness or with neck, shoulder, and respiratory muscle involvement. The neuromuscular junction (NMJ) has been confirmed to be the main target of both AChR-and MuSK-MG. However, histopathological investigation disclosed that muscle fiber atrophy was prevalent in AChR-MG, whereas mild myopathic changes and mitochondrial abnormalities were more frequently observed in MuSK-MG. As the pathogenetic mechanism in MuSK-MG remains unclear, this study investigated the submicroscopic pattern of muscle histopathology to establish a possible correlation between clinical involvement and subcellular morphological findings. Muscle biopsies from seven MuSK-MG patients and from seven patients with AChR-MG were analyzed by transmission electron microscopy. Myopathic and mitochondrial abnormalities were more prominent in MuSK-MG and show giant, swollen, and degenerated mitochondria with fragmented cristae. The most common changes in AChR-MG muscles were fiber atrophy, myofibrillar disarray, and Z-line streaming, consistent with mild neurogenic abnormalities. A different pathogenetic mechanism is emerging in MuSK-MG compared to AChR-MG. Mitochondrial abnormalities seem to be more prominent in MuSK-MG, whereas neurogenic atrophy is observed in AChR-MG.

Original languageEnglish
Pages (from-to)746-752
Number of pages7
JournalJournal of Neurology
Volume258
Issue number5
DOIs
Publication statusPublished - May 2011

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Myasthenia Gravis
Receptor Protein-Tyrosine Kinases
Muscles
Antibodies
Cholinergic Receptors
acetylcholine receptor kinase
Atrophy
Neck Muscles
Respiratory Muscles
Muscular Atrophy
Neuromuscular Junction
Muscle Weakness
Transmission Electron Microscopy
Mitochondria

Keywords

  • AChR-positive myasthenia gravis
  • Mitochondria
  • MuSK-positive myasthenia gravis
  • Transmission electron microscopy

ASJC Scopus subject areas

  • Clinical Neurology
  • Neurology

Cite this

Comparison of muscle ultrastructure in myasthenia gravis with anti-MuSK and anti-AChR antibodies. / Cenacchi, Giovanna; Valentina, Papa; Marina, Fanin; Elena, Pegoraro; Corrado, Angelini.

In: Journal of Neurology, Vol. 258, No. 5, 05.2011, p. 746-752.

Research output: Contribution to journalArticle

Cenacchi, Giovanna ; Valentina, Papa ; Marina, Fanin ; Elena, Pegoraro ; Corrado, Angelini. / Comparison of muscle ultrastructure in myasthenia gravis with anti-MuSK and anti-AChR antibodies. In: Journal of Neurology. 2011 ; Vol. 258, No. 5. pp. 746-752.
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