KMT2D and leukemia: Although originally identified as oncogenic fusions in leukemia 6, recent genome‐wide mutation studies have revealed frequent, presumably loss‐of‐function, mutations in various members of the MLL family, including MLL2/KMT2B, MLL3/KMT2C, and MLL4/KMT2D in a variety of malignancies, particularly solid tumors 7, 8, 9, 10, 11.