USE OF FLUORESCENCE IN-SITU HYBRIDIZATION (FISH) FOR THE ESTIMATION OF THE ABERRANT CELL CLONE IN LEUKEMIAS WITH TRISOMY-8 OR MONOSOMY-7 DETECTED BY KARYOTYPING

The sizes of leukemic cell clones with hypersomies of the chromosome #8 or monosomy #7, which primarily were detected by classical karyotyping, were estimated by fluorescence in situ hybridization (FISH) with centromeric DNA probes in interphase cell populations of the bone marrow of 31 leukemia patients. Particularly, the data obtained by both routes of analysis were compared quantitatively. As most prominent result, all aberrations found by classical karyotyping were redetected by interphase cytogenetics, but additional aberrant clones could be observed among the interphase cell populations. The frequencies of the cell clones with hypersomies #8, in general, were higher in metaphase than' in interphase, and, vice versa, cells monosomic for #7, in the majority of cases, were found to be more frequent in interphase than in metaphase. These data support the idea that metaphase data per se may not sufficiently reflect the actual portions of aneuploid cell clones in the whole leukemic cell population. This may be of practical importance in diagnostic and prognostic respects but also for the choice of specific therapies.