MOG and myelitis: Similarly, MOG-IgG testing was often performed remote from the index myelitis episodes (eTable 2), and seroreversion to MOG-IgG seronegative status over time is known to occur in MOGAD and may confound interpretation of test results.55,56 Furthermore, isolated CSF MOG-IgG seropositivity has been reported to occur in a subset of patients with MOGAD.57, –, 59 In this cohort, CSF MOG-IgG testing was limited to only 4 patients and was negative in all cases (including 1 patient with a diagnosis of MOGAD based on serum testing).