However, subsequently it was discovered that precursor B-cell acute lymphoblastic leukemia has a PBX1/E2A fusion gene characterized by either a der(19)t(1;19)(q23;p13.3) or t(1;19)(q23;p13.3).The probe set designed to identify these translocations [19] was used in the FISH analysis of our case. This evidence concerns the gene PBX1 and B-cell acute lymphoblastic leukemia.