In addition to demethylating CpG-island gene-promoter regions, it increases poly (ADP-ribose) polymerase (PARP1) interaction to DNA and strong association to chromatin, limiting PARP-mediated DNA-repair or -transcription activation, thus downregulating HR DNA repair and making cancer cells more sensitive to the PARP inhibitor [217]. The gene discussed is PARP1; the disease is cancer.