TCF3 and acute lymphoblastic leukemia: Given that these 153 cases were derived from a population-based selection of BCP-ALL [5] and that these fusions do not co-occur with other driver leukemic fusions (BCR-ABL1, rearranged MLL, TCF3-PBX1, ETV6-RUNX1), ABL/JAK class tyrosine kinase fusions cases are estimated to represent approximately 2.5% of pediatric BCP-ALL, making this heterogeneous subgroup similar in size to the BCR-ABL1-positive cytogenetic subtype.