Two subsets of relapsing optic neuritis, one with discrete acute attacks named RION (recurrent isolated optic neuritis), and the other characterized by chronic relapsing inflammatory optic neuropathy with corticosteroid dependence, named CRION, seem to be associated with MOG-IgG antibodies (28) with high seropositivity rates: 7/7 children (29), 11/12 adults (30). This evidence concerns the gene MOG and optic neuritis.