Myelodysplastic/myeloproliferative neoplasms (MDS/MPN) are hybrid group of chronic myeloid neoplasms combining features of both myelodysplastic (MDS) [DS:H01481] and myeloproliferative neoplasms (MPN). This group includes chronic myelomonocytic leukemia (CMML), its pediatric counterpart juvenile myelomonocytic leukemia (JMML), MDS/MPN with ringed sideroblasts and thrombocytosis (MDS/MPN-RS-T), atypical BCR-ABL1 negative chronic myeloid leukemia (aCML) and MDS/MPN- unclassifiable (MDS/MPN-u). Somatic mutations observed in MDS/MPN fall in 4 major categories, including signaling, splicing, epigenetic, and transcription gene mutations.