KMT2D and mantle cell lymphoma: In the last decade, unbiased massively parallel sequencing of whole exomes (WES) and RNA-Seq of MCL have identified recurrent mutations (TP53, ATM, NOTCH1/2, CCND1, HNRNPH1, KMT2D) associated with MCL (6, 17–22) and genetic lesions (del[9p], ARID1A, SMARCA4) that contribute to resistance to chemoimmunotherapy or targeted therapies (21, 23–25).