COMPARATIVE GENOMIC HYBRIDIZATION IN CHRONIC B-CELL LEUKEMIAS SHOWS AHIGH-INCIDENCE OF CHROMOSOMAL GAINS AND LOSSES

In chronic B-cell leukemias, fluorescence in situ hybridization has gr eatly improved the ability to detect certain chromosomal aberrations, as cells in all phases of the cell cycle are analyzed. To obtain a com prehensive view of chromosomal gains and losses, we applied the recent ly developed technique of comparative genomic hybridization (CGH) to 2 8 patients with chronic B-cell leukemias. CGH results were compared wi th those obtained by chromosome banding analysis and interphase cytoge netics. In 19 of the 28 cases, chromosomal imbalances were detected, i ncluding amplified DNA sequences in three instances. The most common a berrations included gains of chromosomal material on 8q and 12 as well as losses of 6q, 11q, 13q, and 17p. In 13 cases, CGH revealed chromos omal gains and losses not detected by banding analysis. In 8 of these 13 cases, discrepancies were further investigated using other methods, and in all instances, the CGH findings were confirmed. A limitation o f detecting small deleted regions by CGH was found in one example of 1 8p. In conclusion, our data show that the results of banding analyses in chronic B-cell leukemias often do not reflect the chromosomal chang es in the predominant cell clone. This may be one explanation for the as yet poor correlation between cytogenetic findings and clinical cour se in this group of neoplasms. (C) 1995 by The American Society of Hem atology.