KMT2D and diffuse large B-cell lymphoma: A growing body of evidence indicates that dysregulated expression or mutation of various HMTs, such as lysine methyltransferase 2D (KMT2D), CREB-binding protein (CREBBP)and enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2), are some of the most common gene abnormalities in DLBCL, directly contributing to the molecular pathogenesis and progression of DLBCL [8, 9].