The TEL and AML1 genes are common targets of chromosomal translocations in
hematopoietic malignancies. The TEL-AML1 fusion gene, created by the t(12;2
1), is the most common genetic alteration in childhood acute lymphoblastic
leukemia and is associated with a favorable outcome. This review summarizes
the roles of the TEL and AML1 proteins in hematopoiesis, the potential tra
nsforming mechanisms of TEL fusion proteins, and the clinical significance
of the TEL-AML1 fusion.