This concept has also been proposed in a previous investigation by Watanabe et al. (30), in which the sGFAP/sNfL ratio was first reported to be higher in NMOSD than in MS patients, especially during NMOSD relapse, although their study included both AQP4-ab-positive and -negative NMOSD patients. Here, AQP4 is linked to myeloid sarcoma.