The genomic landscapes of MDS and myelodyplastic/myeloproliferative (MDS/MPN) overlap syndromes such as chronic myelomonocytic leukemia (CMML) overlap with that of CH and include mutations in genes affecting epigenetic regulation (TET2 and DNMT3A), histone modification (ASXL1 and EZH2), splicing factors (SRSF2, SF3B1, U2AF1, and ZRSR2), signal transduction (NRAS, KRAS, CBL, PTPN11, and JAK2), and nucleosome assembly (SETBP1 and RUNX1) [2]. The gene discussed is PTPN11; the disease is chronic myelomonocytic leukemia.