Specifically, gain-of-function (GOF) mutations in the histone methyltransferase EZH2 (enhancer of zeste homolog 2) or loss-of-function (LOF) mutations in the histone acetyl transferase CREBBP (cAMP-response element binding protein (CREB) binding protein) or EP300 (E1A binding protein P300) or histone methyltransferase KMT2D (lysine methyltransferase 2D), which occur in 30–40% of these diseases, contribute to the repression of antigen presentation, IFN-γ response genes, or CD40 signaling in lymphoma cells (Mlynarczyk et al., 2019). The gene discussed is KMT2D; the disease is lymphoma.