Clinical spectrum and IgG subclass analysis of anti-myelin oligodendrocyte glycoprotein antibody-associated syndromes: a multicenter study

Anti- myelin oligodendrocyte glycoproteinantibodies (MOG- Ab) recently emerged as a potential biomarker in patients with inflammatory demyelinating diseasesof the central nervous system. We here compare the clinical and laboratory findings observed in a cohort of MOG- Abseropositive and seronegative cases and describe IgG subclassanalysis results. Consecutive serum samples referred to Verona University Neuropathology Laboratory for aquaporin-4(AQP4)- Aband/or MOG- Abtesting were analysed between March 2014 and May 2017. The presence of AQP4- Abwas determined using a cell-based assay. A live cell immunofluorescence assay was used for the detection of MOG-IgG and IgG subclassanalysis. Among 454 analysed samples, 29 were excluded due to AQP4- Abpositivity or to the final demonstration of a disorder not compatible with MOG- Ab. We obtained clinical data in 154 out of 425 cases. Of these, 22 subjects resulted MOG- Abpositive. MOG- Abpositive patients were mainly characterised by the involvement of the optic nerve and/or spinal cord. Half of the cases presented relapses and the recovery was usually partial. Brain MRI was heterogeneous while short lesions were the prevalent observation on spinal cord MRI. MOG- Abtitre usually decreased in non-relapsing cases. In all MOG-IgG positive cases, we observed IgG1 antibodies, which were predominant in most subjects. IgG2 (5/22), IgG3 (9/22) and IgG4 (3/22) antibodies were also detectable. We confirm that MOG- Ab-related syndromes have distinct features in the spectrum of demyelinating conditions, and we describe the possible role of the different IgG subclassesin this condition.