The BCR-ABL1 fusion gene exists in three different forms, associated with different types of leukemia: p190 is mainly associated with Ph-positive (Ph+) acute lymphoblastic leukemia (ALL), p210 with 95% of CML, and p230 with a subset of patients with chronic neutrophilic leukemia (CNL). The gene discussed is ABL1; the disease is chronic neutrophilic leukemia.