Background and purpose The aim of this study was to analyse the clinical and prognostic features of myelin oligodendrocyte glycoprotein (MOG) antibody-associated demyelination with different onset phenotypes. Methods A total of 52 MOG-IgG-seropositive patients were divided into four groups: (i) optic neuritis (ON) at onset (MOG-ON+, n = 23), (ii) transverse myelitis (TM) at onset (MOG-TM+, n = 12), (iii) pure brain symptoms at onset (MOG-ON--TM-, n = 14) and (iv) both ON and TM at onset (n = 3). This final group was not included in further analyses. Data were collected through medical records and regular follow-up. Results Median age at presentation was 24 (range, 3-63) years in the whole cohort (50% female). MOG-ON--TM- patients had the youngest age of onset across the three groups. Patients with MOG-TM+ tended to relapse more frequently and had a longer interval to first relapse than was observed in MOG-ON+ and MOG-ON--TM- patients. High MOG-IgG titres were associated with increased cerebrospinal fluid leukocytes. The likelihood of harbouring transient, low MOG-IgG titres was higher in the MOG-TM+ group than in the other groups. After a median disease duration of 20 months, most but not all cases had a favourable outcome, with 8% developing severe visual deficit, 2% becoming wheelchair-dependent and 6% developing cognitive impairment. The onset phenotype appeared to be an important predictor of disability type. Having high MOG-IgG titres (odds ratio, 0.168, P = 0.027) or female gender (odds ratio, 0.270, P = 0.067) was associated with a lower likelihood of complete recovery.
Conclusions Onset phenotype may influence long-term presentation, MOG-IgG status as well as outcome. Further large and prospective studies are needed to better clarify the clinical implications of the first demyelinating event.