ABC DLBCL is characterized by lesions in genes involved in NF-κB pathway and B-cell receptor (BCR) signaling [TNFAIP3 (mutations or 6q23 deletions); MYD88, CD79A, CD79B, CARD11 (mutations)], cell cycle [CDKN2A/B (9p21 deletions)], terminal B cell differentiation [PRDM1 (mutations or 6q21 deletions); SPIB (19q13 gains and amplifications)], and apoptosis [BCL2 (18q21 gains or amplifications)]. The gene discussed is PRDM1; the disease is diffuse large B-cell lymphoma.