This review focuses on the recent progresses in epigenetic modifications in DNA and RNA, including their epigenetic roles, detection methods and applications in clinical medicine.

MicroRNA (miRNA) detection is of considerable significance in both disease diagnosis and in the study of miRNA function.

A conserved guanine-rich sequence could be a new target for anti–hepatitis C virus drug development.

Prokaryotes use repetitive genomic elements termed CRISPR (clustered regularly interspaced short palindromic repeats) to destroy invading genetic molecules. Although CRISPR systems have been widely used in DNA and RNA technology, certain adverse effects do occur. For example, constitutively active CRISPR systems may lead to a certain risk of off-target effects. Here, we introduce post-synthetic masking and chemical activation of guide RNA (gRNA) to controlling CRISPR systems. An RNA structure profiling probe (2-azidomethylnicotinic acid imidazolide) is used. Moreover, we accomplish conditional control of gene editing in live cells. This proof-of-concept study demonstrates promising potential of chemical activation of gRNAs as a versatile tool for chemical biology.