Chronic neutrophilic leukaemia (CNL) is a BCR::ABL1-negative MPN characterized by sustained peripheral blood neutrophilia (white blood cell count (WBC) ≥ 25 × 109/ L, with ≥80% segmented neutrophils and bands), bone marrow hypercellularity due to neutrophilic granulocyte proliferation, and hepatosplenomegaly. This evidence concerns the gene ABL1 and myeloproliferative disorder.