t(5;14)(q33-34;q11), a new recurring cytogenetic abnormality in childhood acute leukemia.

A novel translocation, t(5;14)(q33-34;q11), was identified in the leukemic cells of four children presenting with acute lymphoblastic leukemia (ALL). The patients were 14 months, 2 years, 10 years, and 12 years old; each presented with one or more features of bulky disease, including lymphadenopathy, organomegaly or a mediastinal mass. The leukemic blasts were B lineage in two cases and T lineage in two cases. The patients with B-lineage ALL remain in continuous remission at 22 and 19 months following diagnosis. One patient with T-lineage ALL relapsed 6 months after diagnosis. The other patient with T-lineage ALL developed acute myelocytic leukemia (AML) 17 months after diagnosis; t(5;14)(q33-34;q11) was present in both the lymphoblasts at diagnosis and the myeloblasts at relapse, consistent with a lineage switch from ALL to AML. Rearrangement of the T-cell receptor delta chain (TCRD) gene at 14q11 was demonstrated in the three cases studied, suggesting its involvement in the pathogenesis of these leukemias by alteration of the structure or expression of an unidentified gene(s) on the long arm of chromosome 5.