The unseen majority: Characterizing seronegative MOGAD beyond traditional diagnostic criteria

Myelin oligodendrocyte glycoprotein antibody- associated disease (MOGAD) presents with optic neuritis, transverse myelitis, acute encephalitis or acute disseminated encephalomyelitis (ADEM). Less commonly it may manifest as aseptic meningitis, seizures and fever of unknown origin. We describe a paediatric case of seronegative MOGAD with an unusual clinical and neuroimaging profile. Despite negative serum MOG antibody testing, the patient exhibited features consistent with MOGAD and showed response to pulse methylprednisolone, expanding the known phenotypic spectrum of the disease. Recent studies have reported patients with CSF MOG-IgG but without detectable serum MOG-IgG challenging existing diagnostic criteria and need for further research on utility of CSF MOG antibody testing.