RGC-32 mRNA levels are significantly higher in patients defined as responders compared to non-responders to glatiramer acetate (GA), and RGC-32 levels decline in patients experiencing clinical relapses, all of which warrants future use of RGC-32 as a serum biomarker for the detection of MS patient relapse and response to GA therapy [17]. The gene discussed is RGCC; the disease is myeloid sarcoma.