While astrocyte damage and loss as well as secondary neuroaxonal damage are hallmark features of acute lesions in AQP4-IgG+NMOSD, chronic lesions are characterized by astrocytic fibrous gliosis.29,30 Such an astrocytic fibrous gliosis might underlie the association of chronic brain T2-lesions with sGFAP, but not sNfL, in AQP4-IgG+NMOSD. This evidence concerns the gene AQP4 and Gliosis.