G-quadruplexes (G4s), guanine-rich sequences that are able to fold up in polymorphous secondary structures, have received increasing attention in medicinal chemistry thanks to their occurrence in “hot” regions of the genome. Indeed, there is much evidence that G4s affect genomic instability, telomerase dysfunction, and behave as transcriptional repressor elements. Thus, targeting G4 structures has emerged as an alternative strategy for the potential treatment of several diseases.
