Strengths of the present study include the comprehensive literature search for potentially associated MRI features, the large dataset of NMOSD and MS cases with near complete availability of brain and spine imaging, definition of NMOSD cases through highly specific assays for AQP4 antibodies, age and sex matching of MS cases, blinded assessment of scans and an expansive approach to predictive modelling to optimise the classification of the NMOSD and MS cases. The gene discussed is AQP4; the disease is myeloid sarcoma.