Frequency and distribution of BCP-ALL subtypes among all 516 patients with non-DS BCP-ALL registered in the GBTLI LLA-1999 and LLA-2009 in the Boldrini Children’s Center. The pie chart depicts the percentages of the classical subtypes. Patients with incomplete genetic tests (n = 45) could not be classified. Of these, 177 (34%) cases were classified as B-other ALL, because they lacked t(12;21)(ETV6-RUNX1), t(1;19)(TCF3-PBX1), t(9:22)(BCR-ABL1), and KMT2A-rearrangements, and had ≥44 and <51 chromosomes (or a DNA index of <1.16). Not all B-other cases had samples available for the analyses (n = 33). RNA targeted sequencing was performed on 144 B-other and 40 classical ALL samples. The number of cases belonging to the novel molecular subgroups of B-other ALL are shown in the right bar graph. A comprehensive table with the genetic and demographic information on all the 184 cases is provided in the supplemental material (supplemental Table 8). AJ2E, group of ABL-, JAK2-, and EPOR-fusion cases.