CHIT1 (chitinase 1) GPNMB (glycoprotein non-metastatic melanoma protein B), and CCL18 (C–C motif chemokine ligand 18) were the most upregulated genes in comparison I. CHIT1 showed the highest expression in the rim of chronic active MS lesions, with a 10.2-fold change, compared to the expression in the rim of inactive MS lesions (Figure 2). The gene discussed is GPNMB; the disease is myeloid sarcoma.