Biomarkers for phase switches in multiple sclerosis

Multiple sclerosis (MS) is an idiopathic inflammatory demyelinating disease of the central nervous system. The pathology of MS results from a combination of inflammation, demyelination, remyelination, axonal loss, and axonal repair at varying amounts. This heterogeneity is reflected in a continuum of clinical phases of MS: preclinical radiologically isolated syndrome (RIS) to early clinical phases of clinically isolated syndrome (CIS) and relapsing- remitting MS (RRMS) to progressive phases of the disease. The question whether MS is a single disease or a group of disorders is often raised. Currently, the diagnosis of phases of MS is based on the clinical manifestations and MRI findings, but the biology associated with different clinical phases of MS likely starts earlier than clinical manifestations. There is a continued need for reliable and easy to measure biomarkers for early diagnosis, prognosis prediction, and appropriate alteration of medication management in MS. There are various protein biomarkers of MS identified correlating with the disease phenotype, disability, immune activity, or the clinical course though not validated to utilize in the clinical practice. This chapter summarizes the potential biomarkers for MS diagnosis and their roles in differentiating different phases of MS.