Discontinuous deletions at 11q23 in B cell chronic lymphocytic leukemia

Loss of genomic material in 11q is one of the most common structural chromo some aberrations in B cell chronic lymphocytic leukemia (B-CLL). In order t o characterize the deletions of 11q23 in B-CLL, we performed fluorescence i n situ hybridization (FISH) with eight YAC (yeast artificial chromosome) pr obes on peripheral leukocytes of 30 patients. These YACs form a contig span ning 7.8 Mb at 11q23.1-q23.3. We found deletions in nine out of 30 cases (3 0%) and five of them had discontinuous deletions in this region. The region represented by YAC 755b11 (1.6 Mb in size) was involved in all cases with deletions, supporting the hypothesis that this region might contain a novel gene of pathogenic importance to B-CLL. A more distal region represented b y YAC 785e12 (760 kb in size) was deleted frequently and specifically. Whet her there is another novel gene of pathogenic importance to B-CLL and what is its potential relationship to the deletions in the region represented by YAC 755b11, are issues that require further studies.