After the identification of the RGMa gene as a possible modulator of the immune response in MS [46] and the hypothesis that it might contribute to cell death through interaction with neogenin, the presence of RGMa was reported in both active and chronic lesions in autopsy studies, as well as in normal-appearing white matter (NAWM) or gray matter (NAGM) [7]. Here, RGMA is linked to myeloid sarcoma.