The recent reclassification of NMOSD as a discrete disease distinct from MS has prompted studies that have reviewed treatment outcome in NMOSD and in fact have revealed substantial differences in therapy response and optimum treatment between the two conditions: interferon beta and a number of other MS drugs have been found to be probably ineffective or even detrimental in NMOSD [37] (while others, such as B-cell depleting drugs, may be effective in both disorders), and preliminary studies indicate that the same may hold true for MOG-EM [10, 35]. This evidence concerns the gene MOG and myeloid sarcoma.