TCF3 and acute lymphoblastic leukemia: The most common is der(19)t(1;19)(q23;p13) that is strongly associated with precursor B-lymphoblastic leukemia (B-ALL) and can exist in a balanced and in an unbalanced form both resulting in a juxtaposition of PBX1 gene to TCF3 placing PBX1 under the transcriptional control of TCF3 on der(19).