As early as 2007, there were reports of a higher frequency of Hp among opticospinal form of MS (which in all probability was NMOSD) when compared to conventional MS patients (9, 14) This was confirmed by one of the authors (14) in a later study that incorporated AQP4-IgG assay that showed an association with NMOSD but not MS. The gene discussed is HP; the disease is myeloid sarcoma.