The MDS phenotype of CMML has been associated with mutations of TET2, U2AF1, and SF3B1 [48], and the MPN phenotype with mutations that activate RAS family members, ASXL1, JAK2, SETBP1, SRSF2, and EZH2 [10,22,46]. This evidence concerns the gene JAK2 and chronic myelomonocytic leukemia.