As shown in Fig. 1a, mutations of chromatin-modifying genes were assessed in 619 patients with newly diagnosed DLBCL (the training cohort (N = 316) by whole-genome/exome sequencing (WGS/WES) and the validation cohort (N = 303) by targeted sequencing), including KMT2D, KMT2C, and EZH2 (Category I, encoding methyltransferase, 121, 51, and 18 cases), CREBBP and EP300 (Category II, encoding acetyltransferase, 52 and 42 cases), TET2 (Category III, encoding DNA methylation, 48 cases) and ARID1A (Category IV, encoding chromatin remodeling, 54 cases). The gene discussed is TET2; the disease is diffuse large B-cell lymphoma.