Anti-MUSK myasthenia gravis (MG): clinical features

Pathology

• Anti-MUSK antibodies are present in 30-50% of antibody-negative MG
• They cause pre-synaptic and post-synaptic dysfunction
• There is no loss of junctional folds
• There is no loss of acetylcholine receptor (AChR) density
• The thymus gland is usually normal but cases of thymoma have been reported

Aetiology

Genetics

Facial and bulbar features

Ocular features

Generalised features

Anti-MUSK MG and pregnancy

Variant presentations

Reported triggers

Differential diagnosis: anti-AChR MG

Differential diagnosis: others

Double positive MG (DP-MG)

References

1. Wolfe GI, Oh SJ. Clinical phenotype of muscle-specific tyrosine kinase-antibody-positive myasthenia gravis. Ann N Y Acad Sci 2008; 1132:71-75.
2. Takahashi H, Kawaguchi N, Ito N, Takamichi H, Kuwabara S. Is tongue atrophy reversible in anti-MUSK myasthenia gravis? Six year observation. JNNP 2010; 81:701-702.
3. Sieb JP. Myasthenia gravis: an update for the clinician. Clin Exp Immunol 2014; 175:408-418.
4. Morren J, Li Y. Myasthenia gravis with muscle-specific tyrosine kinase (MuSK) antibodies- a narrative review. Muscle Nerve 2018; 58:344-358.
5. Banerjee A, Nathoo N, Purdy K, Puznak K, Siddiqi Z, Zochodne DW. Muscle-specific tyrosine kinase-associated myasthenia gravis with microscopic thymoma. Can J Neurol Sci 2023 (Online ahead of print).
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Related checklists

• Anti-MUSK myasthenia gravis (MG): investigations
• Anti-MUSK myasthenia gravis (MG): treatment