Along the last few years, the scientific community has deepened its understanding on the genetic aberration associated to MN through the discovery of other recurrently mutated genes such as ASXL1, DNMT3A, EZH2, RUNX1, SRSF2, TET2, TP53 and U2AF1 in MDS [3][4], and ASXL1, CBL, EZH2, NRAS/KRAS, RUNX1, SETBP1, SRSF2 and TET2 in Chronic Myelomonocytic Leukemia (CMML) [5][6][7][8]. The gene discussed is U2AF1; the disease is chronic myelomonocytic leukemia.