Patients with MS have higher percentages of TH17 cells, higher expression of IL-17 in cells near MS lesions and genetic linkage studies have shown the IL-17 and IL-17R genes to be of interest in MS (Matusevicius et al., 1999; Tzartos et al., 2008; Durelli et al., 2009; Muls et al., 2012). The gene discussed is IL17A; the disease is myeloid sarcoma.