T-cell acute childhood lymphoblastic leukemia with chromosome 14 q 11 anomaly: a morphologic, immunologic, and cytogenetic analysis of 10 patients.

Ten patients with T-cell acute lymphoblastic leukemia (ALL) and a chromosome anomaly involving band 14 q 11 are described. Mitotic index of bone marrow blasts was high in all patients (average 3.0%). Lymphoid morphology of the leukemic blasts, however, varied somewhat among the patients. The leukemic cells of 5 patients showed an immunophenotypic profile corresponding to early or common thymic differentiation stages whereas 5 children showed strong expression of CD 3 suggesting a more mature thymic phenotype. Leukemic karyotypes revealed a modal chromosome number of 46 in 9 cases, 92 in one case. A chromosome translocation t(11; 14) (p 13; q 11) was found in 5 cases, a t(1; 14) (p 32; q 11) in 2 cases, a t(10; 14) (q 24; q 11) in one case, a (hitherto undescribed) t(12; 14) (q 22; q 11) in one case, and an inv (14) (q 11 q 32) in one patient. Additional abnormalities were t(3; 10), t(7; 9), dup(7 q), del(6 q), del(10 q), and del(1 q). Of 32 cases with T-cell ALL successfully karyotyped in our laboratory 15 (= 47%) had structural aberrations involving chromosomes 1, 3, 6, 7, 9, 10, 12, 14. Ten of these 15 patients (= 67%) had a chromosome 14 q 11 anomaly. It is concluded that chromosome band 14 q 11, the gene locus of the T-cell receptor alpha-chain, is the most common site for structural chromosome aberrations in T-cell ALL.