Abstract Details

Title Initial Negative Anti-MOG IgG1 Cell-based Assays with Later Seroconversion

Topic Autoimmune Neurology

Presentation(s) P4 - Poster Session 4 (8:00 AM-9:00 AM)

Poster/Presentation
Number 1-008

Objective

To determine the frequency of initial negative followed by positive anti-MOG IgG1 cell-based assays (CBAs) in patients with myelin oligodendrocyte glycoprotein antibody–associated disease (MOGAD).

Background

MOGAD is serologically identified by CBAs for anti-MOG IgG1. While the occurrence of false positives for MOG has been well described, less is known about false negatives or post-presentation seroconversion. Here, we describe patients who were initially anti-MOG IgG1 negative at the acute phase and later were found to be positive.

Design/Methods

We queried the MassGeneral Neuroimmunology database (2016–2025), identifying patients with ≥1 positive anti-MOG IgG test. Inclusion criteria for this case series were fulfillment of the MOGAD-2023 criteria, and having an initial anti-MOG IgG1 CBA that was negative followed by a positive test on repeat serology.

Results Four patients (1.1%) out of 355, with a median age at onset of 50.7 years (IQR 37.3–65.8) were identified; all were male and fulfilled MOGAD-2023 criteria. Index phenotypes consisted of unilateral severe ON (n=1), bilateral ON (n=1), LETM (n=1), and meningoencephalitis/ADEM (n=1). Oligoclonal bands were positive in 1 of 3 patients who were tested (5 unique CSF-bands). First negative serology was obtained a median of 4 days [1–7] from onset. Positive serology occurred at a median of 74 days [38–242] post-onset; first-positive titers ranged 1:20–1:1000. No chronic immunotherapy or plasma exchange was given before the first test; one had received rituximab when the test returned positive. Over a median of 4.8 months [2.3–18.6] of follow-up, two patients had relapses after seroconversion.

Conclusions

Our findings might be explained by analytical issues (assay sensitivity, prozone effect) or by disease evolution (antibody-epitope maturation or fluctuating titers). Isotype mismatch may also reduce detection, as MOG-reactive IgA and IgG3 have been reported. These considerations support repeat testing with serial dilutions, when clinicoradiologic suspicion is high. The retrospective design, and short follow-up limit inference.

Authors/Disclosures
Joao Vitor Mahler, MD PRESENTER	Dr. Mahler has received research support from The Sumaira Foundation.
Fiona J. Salas	Ms. Salas has nothing to disclose.
Mulan Jiang	Ms. Jiang has nothing to disclose.
James V. Nguyen, MD, MEd (Mass General Brigham)	Dr. Nguyen has nothing to disclose.
Rebecca Salky	Rebecca Salky has nothing to disclose.
Gabriela Romanow (Massachusetts General Hospital)	Gabriela Romanow has nothing to disclose.
Marina Vilardo	Miss Vilardo has nothing to disclose.
Monique Anderson, MD, PhD (Mass General Hospital)	Dr. Anderson has nothing to disclose.
Natalia Drosu	Ms. Drosu has nothing to disclose.
Takahisa Mikami, MD (Massachusetts General Hospital)	Dr. Mikami has nothing to disclose.
Rebecca L. Gillani, MD (Massachusetts General Hospital)	The institution of Dr. Gillani has received research support from The Phyllis and Jerome Lyle Rappaport Foundation. The institution of Dr. Gillani has received research support from McCourt Foundation . The institution of Dr. Gillani has received research support from Roche.
Anastasia Vishnevetsky, MD (Massachusetts General Hospital)	The institution of Dr. Vishnevetsky has received research support from National MS Society. The institution of Dr. Vishnevetsky has received research support from NIH (NeuroNext).
Philippe-Antoine Bilodeau, MD (Massachusetts General Hospital)	Dr. Bilodeau has nothing to disclose.
Michael Levy, MD, PhD, FAAN (Massachusetts General Hospital/Harvard Medical School)	Dr. Levy has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Mitsubishi Pharma. Dr. Levy has received personal compensation in the range of $500-$4,999 for serving as a Consultant for UCB Pharma. Dr. Levy has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Sanofi. Dr. Levy has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Alexion. Dr. Levy has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Horizon. Dr. Levy has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Genentech. Dr. Levy has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Elsevier. Dr. Levy has received personal compensation in the range of $10,000-$49,999 for serving as an Expert Witness for Various law firms. The institution of Dr. Levy has received research support from National Institutes Health.
Marcelo Matiello, MD, FAAN (Massachusetts General Hospital, Brigham, Harvard)	Dr. Matiello has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Genentech. Dr. Matiello has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Amgen. Dr. Matiello has received personal compensation in the range of $5,000-$9,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for WoltersKluwer.

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