PLEX has been shown to be an effective treatment for NMO-ON with fewer AEs and more therapeutic effects, due to the elimination of circulating pathogenic macromolecules such as AQP4-IgG, complement, or inflammatory cytokines.[18–20] Emerging evidences have also proved the important value and potential prospect of PLEX in NMO-ON acute phase.[21–25] However, there are controversial about its therapeutic effect and safety. The gene discussed is AQP4; the disease is neuromyelitis optica.