Previous studies using bacterial artificial chromosome or oligonucleotide arrays have identified recurrent deletions of several genes in T-ALL, such as BCL11B (14q32.2), EZH2 (7q36.1), LEF1 (4q25), NF1 (17q11.2), PHF6 (Xq26.2), PTEN (10q23.31), and PTPN2 (18p11.21) [6-12]. This evidence concerns the gene PTPN2 and acute lymphoblastic leukemia.