Association of blocking acetylcholine receptor antibodies with clinical subtypes and disease severity in myasthenia gravis.

Background And Aim: The identification of serum antibodies, particularly acetylcholine receptor antibodies (AChR-ab), is essential for diagnosing myasthenia gravis (MG). However, the clinical significance of blocking AChR-abs (bAChR-ab) and their correlation with disease severity remain underexplored. This study aims to evaluate the distribution of bAChR-ab across MG subtypes and their correlation with clinical severity.

Methods: 148 MG patients were recruited from Huashan Hospital, Fudan University. The positive ratio of nAChR-ab and bAChR-ab was evaluated, and the correlations of bAChR-ab inhibition rate were analyzed in relation to clinical severity.

Results: Of total148 patients diagnosed with MG, 76 (51.35%) classified as ocular myasthenia gravis (OMG) and 72 (48.65%) as generalized myasthenia gravis (GMG). Thymic abnormalities were more common in GMG, with 19.44% of GMG patients having thymoma compared to 9.21% of OMG patients, though the difference was not statistically significant. 43.24% of patients tested positive for bAChR-ab, with a significantly higher positivity rate observed in GMG (58.33%) compared to patients with OMG. Elevated bAChR-ab inhibition rate significantly correlated with disease severity, while nAChR-ab did not demonstrate any correlation with either the MGC score or the ADL score in either groups.

Conclusion: bAChR-ab was exclusively detected and showed a strong association with severe clinical manifestations, including myasthenic crises. These findings highlight bAChR-ab as a potential biomarker for monitoring MG severity. The role of bAchR-ab in seronegative MG will be further verified. Larger, multi-center studies warrant to validate these results and refine diagnostic and therapeutic strategies for MG management.