¹Department of Medical Genetics, Haartman Institute, University of Helsinki, Finland

²Laboratory of Medical Genetics, Helsinki University Central Hospital, Helsinki, Finland

³Department of Human Genetics, National Research Center, Cairo, Egypt

⁴Department of Clinical Chemistry, Tampere University Hospital and University of Tampere Medical School, Tampere, Finland

^aCorrespondence: S Knuutila, Laboratory of Medical Genetics, Helsinki University Central Hospital, PO Box 404 (Haartmaninkatu 3, 4th floor), FIN-00029 HUCH, Helsinki, Finland; Fax: 358 9 1912 6788

Loss of genomic material in 11q is one of the most common structural chromosome aberrations in B cell chronic lymphocytic leukemia (B-CLL). In order to characterize the deletions of 11q23 in B-CLL, we performed fluorescence in situ hybridization (FISH) with eight YAC (yeast artificial chromosome) probes on peripheral leukocytes of 30 patients. These YACs form a contig spanning 7.8 Mb at 11q23.1-q23.3. We found deletions in nine out of 30 cases (30%) 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 by YAC 785e12 (760 kb in size) was deleted frequently and specifically. Whether 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.

B cell chronic lymphocytic leukemia; fluorescence in situ hybridization; yeast artificial chromosome; deletions at 11q23