In the field of CMML recent studies have reported mutations in >90% of patients, affecting genes mainly involved in the following mechanisms: epigenetic regulation (TET2, ASXL1, EZH2, DNMT3A, IDH1/2), spliceosome machinery (SRSF2, ZRSR2, SF3B1, U2AF1), cell signaling and transcription factor regulation (NRAS, KRAS, CBL, JAK2, RUNX1) [6, 7, 11, 15, 20, 21]. This evidence concerns the gene U2AF1 and chronic myelomonocytic leukemia.