Although not proven in the study, the negative results obtained in peripheral blood, with lack of expression of CPXM2 and NLRP9 in PBMC and no evidence of differences in IGSF9B expression between minor allele carriers and non-carriers for rs10894768, suggest that the genetic variants associated with disease course in MS may act by modulating the function of CNS cells such as macrophages/microglia and astrocytes, as supported by the immunohistochemistry studies in MS brain tissue showing expression for these genes in these particular cell types. The gene discussed is IGSF9B; the disease is myeloid sarcoma.