The molecular background of BCP‐ALL is heterogeneous, and some known genetic aberrations that define genetic subtypes of the disease, including breakpoint cluster region‐Abelson kinase 1 (BCR‐ABL1) translocation, mixed lineage leukemia gene rearrangements (MLLr), hypodiploidy, and BCR‐ABL‐like subtype, are associated with poor prognosis (Hunger and Mullighan, 2015). The gene discussed is ABL1; the disease is acute lymphoblastic leukemia.