Primary DLBCL in immune-privileged sites exhibits high-frequency mutations in MYD88 and CD79B, and nodal DLBCL exhibits high-frequency mutations in KMT2D, PIM1, BCL2, CREBBP, and EZH2. However, these mutations rarely occur in GI-DLBCL. The gene discussed is EZH2; the disease is diffuse large B-cell lymphoma.