Detection of l l q 1 3 Rearrangements in Hematologic Neoplasias by Double - Color Fluorescence In Situ Hybridization

Rearrangements within the chromosome l lq13 region are frequent in hematologic malignancies. 50% to 75% of mantle cell lymphomas (MCLs) carry a translocation t(11;14) (q13;q32). Using Southern blot analysis, a BCLl breakpoint can be daected in approximately 50% of MCLs. It is not known whether other MCLs harbor also breakpoints at llq13. Breakpoints in this region not involved in t(ll;l4), are detected in chronic lymphocytic leukemia and acute myeloid leukemia. To detect and localize breakpoints at 11q13 more accurately, we have developed fluorescence in situ hybridization using two probe sets of differently labeled cosmids, symmetrically localized at either side of the major translocation cluster of BCL1. These probes span a region of 450 to 750 kb. We applied this assay to a series of hematologic malignancies with l lq13 abnormalities identified by classical cytogenetics. All four samples with a t(11;14)