Emerging Role of Circular RNAs as Potential Biomarkers for the Diagnosis of Human Diseases.

In the eukaryotic transcriptome, the evolutionary conserved circular RNAs naturally occur from the family of noncoding RNAs. Circular RNAs possess a unique feature to interact with nucleic acids and ribonucleoproteins and are establishing themselves as an obligatory composition for the regulatory messages which are encoded by the genome. The back-splicing mechanism leads to the formation of circularized RNA, and because of this they become resistant to exonuclease-mediated degradation. The differential and aberrant expression of circular RNAs can be detected with the help of various profiling methods by using serum, plasma, and tissue samples. In this chapter, we have highlighted the role of circular RNAs as putative biomarker for the detection of various human diseases along with its profiling methods. Here we have discussed the differentially expressed circular RNAs in neurological disorders and infectious diseases along with cancer diseases. For instance, in case of pulmonary tuberculosis, hsa_circRNA_001937 was upregulated, while hsa_circRNA_102101 got downregulated; Hsa_circ_000178 was depicted to get upregulated in breast cancer which is associated with disease progression. Furthermore, it has been observed that circRNAs are abundantly present within the mammalian brain tissues. In epileptic condition, Circ-EFCAB2 was observed to get notably upregulated within patients. Taking the above conditions into consideration, circular RNAs have proven themselves as promising noninvasive biomarker for the detection of human diseases.