Low incidence of TAL1 gene rearrangements in adult acute lymphoblastic leukemia: A cancer and leukemia group B study (8762)

TAL1 gene rearrangements have been described in approximately 25% of children with T cell acute lymphoblastic leukemia (ALL). Three percent of these rearrangements are the result of a reciprocal translocation, t(1;14)(p34;q11). The remainder of these rearrangements are submicroscopic and involve a nearly precise 90-kilobase pair deletion of the TAL1 gene. Detection of these submicroscopic rearrangements can be accomplished easily using Southern blot and PCR technology and may have potential value for monitoring disease during and following treatment. The incidence of TAL1 gene rearrangements in adults with ALL is unknown. In this pilot study, we performed Southern blot and PCR analysis in a group of newly diagnosed adult ALL patients to determine the incidence of TAL1 rearrangements. Thirty-three adults with T cell ALL were studied; of these, one patient had a t(1;14)(p34;q11) and molecular rearrangement of TAL1. No submicroscopic deletions of TAL1 were detected (95% confidence intervals, 0.000 and 0.106). Unlike pediatric T cell ALL, the incidence of TAL1 rearrangements in adult ALL appears to be very low.