T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy that is classified into different genetic subtypes based upon the aberrant expression of specific transcription factor oncogenes (TAL, TLX1, TLX3 or HOXA) or the arrest at a specific stage of T-cell differentiation (immature T-ALL)1–4. This evidence concerns the gene TLX1 and acute lymphoblastic leukemia.