The chimeric BCR::ABL1 is a diagnostic hallmark of chronic myeloid leukemia (CML), and a recurrent cytogenetic abnormality used for subclassification of B-lymphoblastic leukemia (B-ALL), mixed-phenotype acute leukemia (MPAL), and acute myeloid leukemia (AML) by the 5th edition of the World Health Organization Classification of Hematolymphoid Tumors (WHO-HAEM5) [1,2] and the International Consensus Classification (ICC) guidelines [3,4]. The gene discussed is ABL1; the disease is acute lymphoblastic leukemia.