Furthermore, recent studies have successfully established the characteristics of optical coherence tomography following AQP4‐IgG‐mediated optic neuritis (ON) which have been shown to be useful in differentiating AQP4‐IgG‐mediated ON from MS (Bennett et al., 2015; Oertel, Zimmermann, Paul, & Brandt, 2018; Pache et al., 2016). The gene discussed is AQP4; the disease is myeloid sarcoma.