The DLBCL subtypes and molecular subgroups (left) form clusters with imbalanced representation of COO and other aggressive B-cell lymphomas (middle). Genes most frequently mutated in each cluster are indicated (right, colored bars) along with their relative enrichment when compared with the other groups (inner bars). For genes affected by aSHM (boldface), the presence of any coding or noncoding mutation was used for clustering. Three of these clusters closely resemble those identified previously: the germinal center B-cell (GCB)-enriched BCL2 cluster (or EZB/C3) and the activated B-cell (ABC)-predominant MYD88 cluster (MCD/C5), and the NOTCH2 cluster, which was also previously identified (BN2/C1) and comprises a balance of COO subgroups. The NEC cluster represents tumors lacking sufficient features to allow inclusion elsewhere. The TET2/SGK1 and SOCS1/SGK1 clusters were both newly identified and are both enriched for SGK1 mutations. DHITsig indicates GCB-DLBCL either positive or negative for the double-hit gene expression signature.¹⁰  CNS, central nervous system; tFL, transformed follicular lymphoma; UNC, unclassifiable.