Use of circulating nucleic acids, metabolites, and proteins as clinical biomarkers for earlier prognosis and diagnosis of disease

Abstract

Abstract Biological markers or biomarkers are defined as quantifiable cellular, biochemical, or molecular alterations in tissues, cells, or fluids. They serve as indicators of a normal biological process or disease and/or response to a drug/condition/stress. Circulating biomarkers, that is, biomarkers that can be quantitated from biological fluids, offer marked advantages over tissue-specific and clinical biomarkers that include lesser cost, ease in measurement and analysis, are less time consuming, and reduce the number of subjects required to perform a clinical trial and ethical problems associated with the measurements of clinical end points. Various high-throughput molecular techniques are currently being developed for the identification of novel biomarkers linked with pathological conditions and disorders. This chapter deals with the different circulating biomarkers—nucleic acids, proteins, metabolites, etc.—tools and techniques used for their analysis, limitations in the study of these circulating biomarkers, and the biomarkers currently in use for prognosis/diagnosis of diseases.