Clinical Features and Outcome of T-ce l l Acute Lymphoblastic Leukemia in Childhood With Respect to Alterations at the T A L l Locus: A Pediatric Oncology Group Study

Alteration of the TAL 1 locus is the most common nonran-dom genetic defect in childhood T-cell acute lymphoblastic leukemia (T-ALL). To determine if rearrangements of the TAL 1 proto-oncogene confer a distinct leukemic phenotype, we studied leukemic peripheral blood or bone marrow samples from 182 children with newly diagnosed T-ALL enrolled on Pediatric Oncology Group treatment protocols. Forty-eight (26%) of the samples had a local rearrangement of the TAL 1 locus. Demographic and clinical features were compared for patient subgroups with and without TALl rearrangements. The only clinical correlates that were sig-nificantly associated with TAL 1 gene rearrangements were higher white blood cell count (P =.017) and higher he-ERTAIN LYMPHOID TUMORS, such as Burkitt’s C lymphoma and follicular B-cell lymphoma, are char-acterized by unique chromosome abnormalities present in