The progression of disability in MS seems to inversely correlate with iron concentration, especially in a deep grey matter on MRI imaging (quantitative susceptibility mapping), which could have prognostic and diagnostic value (e.g., helping to differentiate between relapsing or primary progressive MS and in AQP4-antibody seropositive NMOSD) (82–84). This evidence concerns the gene AQP4 and myeloid sarcoma.