The worst prognosis for ALL patients is seen in the presence of t(9;22)(q34;q11), which originates the Philadelphia chromosome (Ph), and at the breakpoint, the chimeric gene BCR activator of RhoGEF and GTPase::ABL proto-oncogene 1 (BCR::ABL1) [2]. The gene discussed is ABL1; the disease is acute lymphoblastic leukemia.