Several epigenetic modulators are recurrently mutated in acute myeloid leukemia (AML) and T-cell acute lymphocytic leukemia (T-ALL), including methylation regulators (DNMT3A, TET2, IDH1/2) and histone writers (EZH2, SUZ12, KMT2A, KDM6A)1,2. The gene discussed is KMT2A; the disease is acute myeloid leukemia.