Examples of biomarkers in the progression of MS are (i) MxA expression defining the pathological effect of interferon-β (IFN-β) in vivo [18], (ii) TNF-related apoptosis-inducing ligand (TRAIL), a potential biomarker of IFN-β therapeutic efficacy [19], (iii) complement regulator factor H, a serum biomarker predicted to be effective in disease progression [20], and (iv) the genes CHI3L1 and NF-L, recently identified as biomarkers for mild cognitive impairment in early stages of MS at genomic levels [21]. The gene discussed is CHI3L1; the disease is myeloid sarcoma.