Background MOG-antibody disease has been recently recognized as a demyelinating condition distinct from Multiple Sclerosis. Methods: A single-site study of 106 MOG-antibody positive patients (including a 63-patient incident cohort) describing the clinical phenotype and outcome.

Results ON was the most common onset presentation (51%) and was bilateral in about half. From the survival curve analysis in the incident cohort we estimated that 38% of patients relapsed within 18 months. The risk was lower in patients immunosuppressed for >3 months (p=0.013). Permanent motor disability (EDSS ≥6; limited walking distance) and visual acuity ≤6/36 in at least one eye occurred in 3.7% and 13.2% respectively after a median disease duration of 68 months (range 2–484). Permanent bladder dysfunction was present in 23.6% patients and around 2/3 of these had bowel dysfunction. 20% of males had permanent erectile dysfunction (44% of males with TM at onset).

Conclusion This is the largest single-centre cohort and the only incident cohort published, and shows that MOG-antibody disease is often relapsing but may be modified with 6–12 months of prednisolone. The prognosis is typically good, better than AQP4-antibody positive disease, but many patients are left with significant sphincter and erectile dysfunction and some with visual impairment.