Among those cytokines that showed significant differences by Kruskal–Wallis test in the relapse phase, IL-17A, IL-6, CXCL8, G-CSF, CCL4, and CXCL10 levels were higher in NMO/NMOSD patients than in OND patients assessed by the Steel-Dwass test (IL-17A: p = 0.0074; IL-6: p = 0.000076; CXCL8: p = 0.0003; G-CSF: p = 0.011; CCL4: p = 0.0092; CXCL10: p = 0.00022). This evidence concerns the gene IL17A and neuromyelitis optica.