Indeed, due to the fact many childhood ALL cases carry specific fusion genes (MLL gene fusions, ETV6/RUNX1, E2A/PBX1, etc.)and AML (AML1/ETO, PML/RARα, CBFβ/MYH11, etc.), this gives more evidence that childhood AL is initiated in utero during fetal hematopoiesis [8]. This evidence concerns the gene TCF3 and acute lymphoblastic leukemia.