Cytogenetic studies in T-cell acute lymphoblastic leukemia (1981-2002).

Chromosomal analysis was successfully performed in 34 of the 37 patients with T-cell acute lymphoblastic leukemia (ALL) seen at the University Hospital in Brest (France) between 1981 and 2002. A normal karyotype was observed in 29.4% of the patients. Numerical changes were rare, 79.2% of the abnormal karyotypes being pseudodiploid. All 24 abnormal karyotypes had at least a structural rearrangement. Translocations involving band 14q11, that contains the T-cell receptor (TCR) alpha and delta-genes, were observed in 8 patients; in 3 of them, a new partner chromosomal band was found. The short arms of chromosomes 11 and 12 were involved in 3 and 2 translocations respectively. Three patients had a del(6q). Our results are in agreement with those of the literature. Most of the recurrent abnormalities are different from those of B-lineage ALL. Some are known to involve TCR genes whereas others can lead to the discovery of new genes that are important to T-lineage leukemogenesis.