ASXL1 (additional sex combs like 1) is a gene that is mutated in a number of hematological neoplasms including Myelodysplastic Syndrome (MDS), Acute Myeloid Leukemia (AML), Myeloproliferative Neoplasms (MPN), Chronic Myelomonocytic Leukemia (CMML) and Chronic Myeloid Leukemia (CML). This evidence concerns the gene ASXL1 and chronic myelomonocytic leukemia.