Circular RNAs as promising biomarkers for human diseases: An update for 2018–2025

Circular RNAs (circRNAs) are a class of endogenous non-coding RNAs characterized by their unique covalently closed-loop structure. These molecules are key regulators of gene expression and are closely linked to various human diseases. Due to their intrinsic stability, evolutionary conservation, and tissue-specific expression, circRNAs have emerged as highly promising biomarkers for a wide range of diseases. This review comprehensively synthesizes progress in research from 2018 to 2025 on the biogenesis, nuclear export, and functional mechanisms of circRNAs in human diseases. Further, we update novel detection technologies and methods of circRNAs and discuss the prospects and challenges of translating circRNAs into clinical biomarkers, aiming to facilitate clinical applications.