The following chromatin modifier genes are recurrently mutated in GCB‐DLBCL and FL: KMT2D (30‐80% of cases), CREBBP (30‐40%), EZH2 (30%), TET2 (10% and founder mutation in DLBCL), EP300 (10%).39, 40, 41 CREBBP and HDAC3 oppose each other via BCL6 during the GC reaction and control the transition from the dark to light zone of GC to its exit.42 CREBBP and EP300 mutations disrupt enhancer switches, causing the sustained repression of enhancers targets by BCL6/HDAC3 complexes.43, 44 (Figure 1). This evidence concerns the gene TET2 and diffuse large B-cell lymphoma.