Objective:

To characterize gut microbiota and fecal metabolome in Myasthenia Gravis (MG), identify diagnostic biomarkers, and explore associations between microbial taxa, metabolites, and clinical severity, highlighting the importance of these biomarkers in MG management.

Key Findings:

• MG patients exhibited significantly reduced alpha- and beta-diversity in gut microbiota.
• 232 discriminative taxa identified, with depletion of butanoic acid-producing commensals and enrichment of Klebsiella.
• 567 altered metabolites were found, including reduced short-chain fatty acids and secondary bile acids.
• Random Forest model achieved AUC = 1.0 for metabolite biomarkers.
• Positive correlations were found between specific bile acids and clinical severity measured by the Quantitative Myasthenia Gravis Score (QMGS).

Interpretation:

The distinct gut dysbiosis and metabolic disturbances in MG patients suggest potential microbial and metabolic biomarkers for diagnosis and therapeutic targeting, warranting further investigation into their clinical applications.

Limitations:

• Small sample size may limit generalizability.
• Cross-sectional design does not establish causality.
• Potential biases in sample collection and participant selection may affect results.

Conclusion:

The study identifies specific microbial and metabolic alterations in MG, offering insights for diagnostic and therapeutic strategies.