A new review headed by Daisy proposes the existence of two classes of R-loops characterized by distinct properties with implications for our understanding of the relationship between R-loops and genome instability.

Schematic of proposed classes of R-loops: “promoter-paused” R-loops and “elongation-associated” R-loops. Shading represents population distribution of R-loops for the two classes.

Promoter-paused R-loops are best captured under native conditions and occur in the immediate surrounding of the promoter region and transcription start site. Elongation-associated R-loops form throughout the gene body and transcription termination site.

Here are the links to the work:

• Pubmed: https://pubmed.ncbi.nlm.nih.gov/34303066/
• Journal Site: https://www.sciencedirect.com/science/article/pii/S1568786421001385