First, CBL mutations are most frequently observed in a distinct group of myeloid disorders, namely myelodysplastic syndromes-myeloproliferative neoplasms (MDS/MPN); this subgroup of hematological malignancies includes the chronic myelomonocytic leukemia (CMML), atypical chronic myeloid leukemia (aCML) and juvenile myelomonocytic leukemia (JMML). This evidence concerns the gene CBL and atypical chronic myeloid leukemia, BCR-ABL1 negative.