The most common recurrent cytogenetic abnormalities in T-lymphoblastic leukemia (T-acute lymphoblastic leukemia [T-ALL]) involve T-cell receptor (TCR) loci and a variety of partner genes, including HOX11, HOX11L2, MYC, and TAL1.
T cell lymphoblastic leukemia (T-ALL) is known to be associated with chromosomal abnormalities that lead to aberrant expression of a number of transcription factors such as TAL1, which dimerizes with basic helix-loop-helix (bHLH) E proteins and inhibits their function.
The SCL gene (also called Tal-1 or TCL5) was identified because of its association with chromosomal translocations in childhood T-cell lymphoid leukemias.
Our Southern blot analyses of a large series of 313 acute leukemias with a specific tal-1 deletion probe (SILDB) demonstrated that tal-1 deletions exclusively occur in T-cell acute lymphoblastic leukemia (T-ALL) and not in precursor B-ALL or acute non-lymphocytic leukemias.