Elevated serum levels of C-terminal agrin fragment in acetylcholine receptor antibody-positive myasthenia gravis

Agrin is essential for neuromuscular junction (NMJ) formation and maintenance. The C-terminal agrin fragment (CAF), generated by neurotrypsin-mediated cleavage of agrin, has been gaining attention as a potential biomarker for sarcopenia. We investigated serum CAF levels in myasthenia gravis (MG), a NMJ disorder. Compared to healthy controls, serum CAF levels were significantly elevated in acetylcholine receptor antibody-positive MG (AChR-MG) patients, but not in muscle-specific kinase antibody-positive MG patients. In AChR-MG, baseline and post-treatment CAF levels inversely correlated with post-treatment MG activities of daily living scores, suggesting that elevated CAF levels may reflect protective mechanisms against AChR-MG pathogenesis, such as improved NMJ regeneration. [Display omitted] •Serum C-terminal agrin fragment (CAF) levels were elevated in AChR-MG patients.•No significant difference in serum CAF levels between MuSK-MG and healthy controls.•Serum CAF levels inversely correlated with post-treatment MG-ADL scores in AChR-MG.•Elevated serum CAF may reflect a protective response against AChR-MG pathogenesis.