MOG-IgG-associated demyelination: focus on atypical features, brain histopathology and concomitant autoimmunity

Introduction Antibodies to myelin oligodendrocyte glycoprotein (MOG) have been demonstrated in patients with optic neuritis (ON), encephalitis and myelitis. Objective To describe the clinical and paraclinical features in patients with MOG-associated demyelination, focusing on unusual cases, brain biopsy and concomitant autoimmunity. Methods A single centre retrospective observational case series, analysing demographic, clinical, laboratory, histopathology and radiological data from MOG- positive patients. Results We identified 20 adults. The male/female ratio was 1.5. Mean age at onset was 31.6 years and mean disease duration was 7.5 years. The most frequent presentation was myelitis (45%), followed by ON (30%). One case had simultaneous myelitis and ON. Two patients had a cortical syndrome, 1 patient had an encephalopathic presentation and 1 cryptogenic focal epilepsy. Anti-neutrophil cytoplasmic antibodies (ANCA) were found in 3 cases, while 1 patient had an antibody to glutamic acid decarboxylase (GAD). Brain biopsy was performed in 2 patients. Relapsing course was identified in 60% of patients. We also discuss 3 cases with atypical features, brain histopathology and concomitant autoimmunity. Conclusion MOG- associated demyelination represents a new disease entity. Unusual cases are reported, expanding the disease spectrum. Elucidating this further should be the focus of prospective studies.