Mutations previously reported in DLBCL are TANK and TNFRSF11a/RANK (positive regulators of nuclear factor (NF)‐κB pathway), EZH2, HIST1H1C, and HIST1H1E (chromatin modulating proteins), KMT2B/MLL2 (encodes histone methyltransferase), DTX1 (WWE1 domain), CIITA, FCGR3A, and ATM (Ataxia‐telangiectasia). The gene discussed is KMT2B; the disease is cerebellar ataxia.