Somatic PHF6 mutations are seen in 38% of T-cell acute lymphocytic leukemia (T-ALL) [9], in 3–6% of AML, myelodysplastic syndrome (MDS), and chronic myelomonocytic leukemia (CMML), and in 23% of mixed-phenotype acute leukemia (MPAL) and undifferentiated leukemia [10–16]. The gene discussed is PHF6; the disease is acute lymphoblastic leukemia.