Researchers discovered a higher risk of recurrence among patients with neuromyelitis optica spectrum disorder (NMOSD) whose anti-aquaporin-4 immunoglobulin G (AQP4-IgG) antibody serostatus converted from AQP4-IgG+ to AQP4-IgG- and back to AQP4-IgG+ again, as published in Multiple Sclerosis and Related Disorders.

However, the researchers observed no significant differences in clinical symptoms overall between patients with AQP4-IgG+ and patients with AQP4-IgG-.

“AQP4-IgG serostatus can fluctuate in the different phases of NMOSD,” the researchers wrote. “We noted that a few NMOSD patients whose AQP4-IgG serostatus changed from negative at first diagnosis to subsequently positive without relapse during the observation period.”

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“By contrast, AQP4-IgG serostatus in a few NMOSD patients with AQP4-IgG+ at the first diagnosis changed to negative for a period of time, and then regained positive, and most of these patients had a recurrence immediately or shortly after diagnosis.”

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The research team followed 84 patients with stable NMOSD over a period of 36 months, checking AQP4-IgG serostatus every 6 months and again if the disease relapsed. The patients were divided into the following groups: 1) AQP4-IgG+ at diagnosis, 2) AQP4-IgG- at diagnosis, 3) persistent AQP4-IgG+, 4) persistent AQP4-IgG-, and 5) conversion to AQP4-IgG-.

The patients’ clinical characteristics were analyzed and compared. While the authors observed fluctuations in AQP4-IgG serostatus over time, there was no significant difference in the clinical characteristics or symptoms between AQP4-IgG+ and AQP4-IgG- patients. Therefore, changes from AQP4-IgG+ to AQP4-IgG- might not represent an appropriate treatment target.

However, those who converted from AQP4-IgG+ to AQP4-IgG- and back to AQP4-IgG+ were more likely to relapse, thus the research team recommends extra vigilance on the part of clinicians as well as longitudinal testing of AQP4-IgG status, particularly in those patients who are AQP4-IgG+ at the onset of the disease.


XZhang X, Liu X, Yu H, et al. Longitudinal evaluation of clinical characteristics of Chinese neuromyelitis optica spectrum disorder patients with different AQP4-IgG serostatus. Mult Scler Relat Disord. Published online April 1, 2022. doi:10.1016/j.msard.2022.103786