Recently, a new subgroup called Early T-lineage progenitor T-ALL (ETP-ALL) which shows a block at the earliest stages of T-cell differentiation and lacks expression of several T-cell surface markers [Cluster of Differentiation (CD)1a, CD8, and CD5] but instead expresses myeloid and stem cell markers, has been described [2,3]. This evidence concerns the gene CD5 and acute lymphoblastic leukemia.