In fact, many of the proteins that are responsible for maintaining and operating the two epigenetic switches are encoded by genes that are some of the most frequently mutated in DLBCL, including KMT2D, CREBBP, EP300, and EZH2. Additionally, the all-important BCL6 exerts its repressive effects at the promoters or enhancers of target genes by forming complexes with histone-modifying enzymes that alter the epigenetic landscape. This evidence concerns the gene KMT2D and diffuse large B-cell lymphoma.