Both GCB-DLBCL and ABC-DLBCL share genetic lesions that lead to inactivation of chromatin modifiers, owing to mutations in CREBBP, EP300 and MLL2 [15, 19, 20, 29], as well as to immune escape, owing to inactivation of β2 microglobulin (B2M), CD58 and genes encoding human leukocyte antigens (HLA-A, HLA-B and HLA-C) [15, 19, 20, 29, 108]. The gene discussed is KMT2D; the disease is diffuse large B-cell lymphoma.