Various types of rearrangements target TLX3 locus in T-cell acute lymphoblastic leukemia

Most chromosomal translocations observed in T-cell acute lymphoblastic leukemia (T-ALL) often produce transcriptional activation of transcription factor oncogenes. Ectopic expression of the TLX3 (also known as HOXIIL2) gene has been shown to be associated with a cryptic t(5; 14)(q35;q32) translocation specific for a subtype of T-ALL. Here we report several examples of variant and alternative translocations resulting in expression of TLX3 in T-ALL, and we describe three of these translocations in detail. In particular, the CDK6 gene was rearranged in two t(5;7)(q35;q21) translocations. In two additional instances, fusion of the BCLIIB (also known as CTIP2) and RANBP17/TLX3 loci were shown to result from subtle genomic insertion/deletion within these loci. This study further underscores that TLX3 expression in T-ALL is strongly associated with the presence of genomic rearrangements. (C) 2004 Wiley-Liss, Inc.