Out of 644 patient samples with different myeloid and lymphoid malignancies and 344 cell hematopoietic and non-hematopoietic lines, the pGly870Ser SETBP1 mutation occurred in 24% of patients with aCML, and in 25, 10, and 4% of patients with chronic neutrophilic leukemia (CNL), unclassified MDS/MPN disorders, and chronic myelomonocytic leukemia (CMML), respectively. The gene discussed is SETBP1; the disease is chronic myelomonocytic leukemia.