Chronic myeloid leukemia (CML) is a type of hematological malignancy that is often caused by the BCR (breakpoint cluster region)–ABL (Abelson proto-oncogene), a fusion product of BCR and ABL kinase triggered by chromosome translocation (1, 2). The gene discussed is ABL1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.