Contribution of comparative genomic hybridization and fluorescence in situ hybridization to the detection of chromosomal abnormalities in B-cell chronic lymphocytic leukemia

Background: B-chronic lymphocytic leukemia (B-CLL), the most common type of leukemia in Western Europe and the United States, is characterized by clonal chromosomal abnormalities detected in almost half of the studied patients. The precise determination of chromosomal changes helps to indicate the prognosis and to understand the pathogenesis of CLL. Methods and Patients: We applied conventional cytogenetics (CC), FISH and comparative genomic hybridization (CGH) to the investigation of clonal abnormalities in 88 B-CLL patients at the time of diagnosis. Results: By using CC of bone marrow cells without any stimulation, non-random chromosomal changes were found in 17 (19%) of 88 patients. The employment of FISH and CGH revealed chromosomal changes in additional 33 patients, thus increasing the detection rate of chromosomal abnormalities to 57%. The most common abnormalities detected in our patients included deletions of 13q in 16 cases (18%), followed by trisomy of chromosome 12 in 12 patients (13%), deletions of 11q in 10 patients (11%) and deletions of 17p in 10 patients (11%). A statistically significant correlation between higher disease activity and the presence of deletions 11q and 17p was observed. Conclusion:The addition of FISH and CGH to CC in 88 B-CLL patients improved the detection of clonal chromosomal changes from 19 to 57%. The most frequent chromosomal change was deletion of 13q14 (18%). Deletions of 11q23 and 17p13 were found in patients with higher clinical disease activity. Our results underline the importance of employing FISH and CGH techniques in CLL patients. CC without any stimulation has a low detection rate and is not suggested for detection of chromosomal changes in CLL.