Frequency of anti-GQ1b IgG antibody in miller fisher syndrome: a Chinese single center study.

Background: The anti-GQ1b IgG antibody has been traditionally regarded as a sensitive marker for Miller Fisher syndrome (MFS). Nevertheless, its prevalence might vary across regions and could be affected by the coronavirus disease 2019 (COVID-19) pandemic. This retrospective study was designed to evaluate the positivity rate of the anti-GQ1b IgG antibody among MFS patients admitted to a single Chinese center and to examine the influence of the COVID-19 pandemic thereon.

Methods: We retrospectively analyzed the medical records of patients diagnosed with MFS and admitted to our hospital from January 2018 to March 2024. Anti-ganglioside antibodies were tested in acute-phase serum samples using enzyme-linked immunosorbent assay (ELISA) or immune-dot assays.

Results: Of the 72 patients admitted for MFS, 51 were tested for ganglioside antibodies. Only 9 (17.65%) of the tested patients were found to have the anti-GQ1b IgG antibody. The positivity rate of the antibody was comparable between patients with the complete form of MFS and those with the incomplete form (17.39% vs. 17.86%, P = 0.965). Additionally, the positivity rate was significantly lower during and after the COVID-19 pandemic compared to before the pandemic (8.33% vs. 40.00%, P = 0.007).

Conclusions: The anti-GQ1b IgG antibody is infrequently detected in MFS patients admitted to our center, especially during and after the COVID-19 pandemic. Future prospective multicenter investigations are expected to contribute significantly to the further clarification of the prevalence of anti-GQ1b IgG antibody in MFS patients across various regions of China.