An R-loop is a three-stranded nucleic acid structure, which consists of a DNA-RNA hybrid duplex and a displaced single stranded DNA (ssDNA) [REF].
Under abnormal conditions, namely elevated production of DNA-RNA hybrids, R-loops can cause genome instability by exposing single-stranded DNA to endogenous damages exerted by the action of enzymes such as AID and APOBEC, or overexposure to chemically reactive species [REF].