While it is still debated whether the primum movens of MS is peripheral (activation of the immune system against myelin epitopes) or central (CNS damage, demyelination, and microglial activation prior to the breakdown of the BBB and the invasion by peripheral immune cells), it is now accepted that, in addition to CD4+ T helper (Th) cells (Th1/Th17), cytotoxic CD8+ T cells, B cells as well as CNS-resident cells, namely microglia and astrocytes, play an important role in the disease [37,38,39,40,41]. The gene discussed is CD4; the disease is myeloid sarcoma.