In optic neuritis without MS occurrence, STAT4 (rs10181656, rs7574865, rs7601754, rs10168266) haplotypes G-G-A-C and C-T-A-T were found to be associated with 32.6- and 9-fold increased odds of ON without MS (p = 0.002, p = 0.016, respectively). This evidence concerns the gene STAT4 and optic neuritis.