SIL-TAL1 deletion in T-cell acute lymphoblastic leukemia.

The TAL1 gene on chromosome 1 encodes a hematopoietic transcription factor. Disruption of TALI via chromosomal translocation or a site-specific deletion has been reported in up to 30% of T-cell acute lymphoblastic leukemias (T-ALL). Here we used a polymerase chain reaction (PCR) assay to identify the 90 kb SIL-TAL1 deletion in a group of 19 cutaneous T-cell lymphomas and a series of 142 T-ALL patients (76 children, 66 adults). While none of the T-cell lymphoma exhibited a SIL-TAL1 recombination, seven T-ALL cases showed a type d1 and two patients a type d2 deletion. Of pediatric T-ALL, 9% (7176) and of adult patients only 3% (2166) were characterized by this genomic lesion. The deletion correlated with commitment to the T-cell receptor (TCR) αβ lineage, but lacked association with a distinct maturation stage