ABL1 and precursor B-cell acute lymphoblastic leukemia: B-ALL harboring the t(9;22)(q34;q11) translocation or ‘Philadelphia chromosome’ (Ph + B-ALL), encodes the fusion gene BCR-ABL1. This translocation is present in 3-5% of childhood B-ALL cases [33] and is associated with older age, higher leukocyte count, and more frequent CNS involvement at time of diagnosis [34].