Based on the hypothesis that CRION may involve more than the optic nerve, we compared the degree of cerebral atrophy among patients with CRION (most of whom were seropositive for MOG-Abs), those with RION (only one with MOG-Abs), and patients with MS and a history of optic neuritis (MS-ON) in an attempt to identify CRION biomarkers. This evidence concerns the gene MOG and myeloid sarcoma.