MuSK Antibody Levels May Correlate With Disease Severity in MuSK Myasthenia Gravis
Retrospective study analyzed longitudinal data from six immunotherapy-naive MuSK-MG patients over 2013-2024, finding significant positive correlation between MuSK antibody levels and disease severity as measured by MG-ADL scores. The correlation was specific to MuSK antibodies, with total IgG showing no independent relationship.
Serial monitoring of muscle-specific kinase (MuSK) antibodies could help in assessing the severity of myasthenia gravis (MG), according to a new study published in the Journal of Neuroimmunology.
The retrospective study analyzed longitudinal data from January 1, 2013, to December 31, 2024, on six immunotherapy-naive MuSK-MG patients, yielding 103 observations for the primary analysis and 81 data points for the secondary analysis. MG is an autoimmune disorder primarily characterized by muscle weakness affecting the face and neck muscles, as well as overall fatigue.
Researchers used generalized linear mixed-effects models to assess the relationship between MuSK antibody levels and MG Activities of Daily Living (MG-ADL) scores. The primary analysis found a significant positive intrapatient correlation between MG-ADL scores and MuSK antibody titers, with an F ratio of 17.48, supported by patient-level scatter plots.
A secondary analysis assessed whether the correlation with MuSK antibodies was a reflection of general immune status. This analysis included both MuSK antibody levels and total IgG level as fixed effects. MuSK antibody level was positively, significantly, and specifically correlated with MG-ADL score (F ratio = 10.97), whereas total IgG level had no independent correlation (F ratio = 0.27).
The researchers concluded that MuSK antibody levels serve a specific clinical role in correlating with intrapatient disease activity, showing the utility of MuSK antibody levels as a means of monitoring therapeutic response, as it is indicative of a specific pathogenic process.
The study had several limitations, including a small sample size from a single center, retrospective design that could introduce selection bias, and the inability to determine interpatient correlation. The authors noted that future studies will need to confirm the finding in larger cohorts of patients diagnosed with MuSK-MG.