ETP-ALL was recognized based on previously defined criteria (cCD3 positive, CD1a negative, CD5dim/negative; lack of expression of both CD4 and CD8; and positivity of stem cell and/or myeloid markers [HLA-DR, CD13, CD33, CD34, or CD117]) (16, 18, 19). This evidence concerns the gene CD4 and acute lymphoblastic leukemia.