Atypical chronic myelogenous leukemia (aCML), BCR/ABL1 negative is a rare myelodysplastic/myeloproliferative neoplasm, usually manifested with hyperleukocytosis without monocytosis or basophilia, organomegaly, and marked dysgranulopoiesis. This evidence concerns the gene BCR and atypical chronic myeloid leukemia, BCR-ABL1 negative.