To determine if similar structural abnormalities occurred recurrently in TAL1 patients, 134 primary T-ALL samples were analysed by high-density Affymetrix SNP array-6 analysis; an ~700-bp region surrounding the Jurkat insertion site was also sequenced in a subset of 93 samples and six cell lines; in parallel, the literature was reviewed for cases with unexplained TAL1 activation. Here, TAL1 is linked to acute lymphoblastic leukemia.