Deletions of Human Chromosome Region 6q23-24 in B-Lineage Neoplasias

Deletions of the long arm of chromosome 6 (6q) are among the most frequent chromosome aberrations in B-lineage leukemias and lymphomas and often occur as secondary changes in addition to typical translocations, such as t(14;18). Using fluorescence in situ hybridization (FISH) with two YAC-DNA probes hybridizing to human chromosome region 6q23–24 and with the centromeric probe D6Z1 as internal control, we studied 31 low-grade and 8 high-grade B-cell lymphomas. Deletions in 6q23–24 were detected in 21 cases (54%) by FISH, compared to 13 cases (33%) by chromosome analysis. Deletions in 6q23-24 were found by FISH in 5/13 small lymphocytic lymphomas, 2/3 mantle cell lymphomas, 10/14 t(14;18)-positive follicular lymphomas and in 4/8 centroblastic lymphomas, three of the latter carrying a translocation t(14;18). This study demonstrates that in B-cell lymphomas deletions in 6q23-24 are present more frequently than suggested hitherto and that they can be detected more sensitively by FISH than by chromosome analysis. In contrast to previous reports suggesting the region 6q23-24 to be preferentially deleted in low-grade lymphomas lacking the translo cation t(14;18), our results indicate that deletions in 6q23–24 appear to be also common in other pathological subsets of B-cell lymphomas, especially in follicular lymphomas carrying the translocation t(14;18).