engleski

Trisomy 8 as the sole chromosomal aberration in myelocytic malignancies: a comprehensive molecular cytogenetic analysis reveals no cryptic aberrations

The study was performed with the goal of searching for cryptic chromosome 8 changes in 13 cases of myelocytic malignancies with trisomy 8. Multicolor banding (MCB) with a chromosome-8-specific probe set was done. According to the available number of metaphase spreads, 8 to 662 mitoses per case were examined ; between 2 and 172 mitoses with trisomy 8 were among the evaluated metaphase spreads. A comprehensive analysis at a MCB resolution of 20 bands per chromosome 8 was performed. This corresponds to 510 bands per haploid karyotype, which is a resolution rarely reached in GTG-banding analysis of bone marrow derived chromosomes. We detected no cryptic structural changes, neither in those eight cases in which trisomy 8 was the only aberration nor in the five cases in which the gain of chromosome 8 was only one change among others. These results indicate that trisomy 8 remains cytogenetically the same in early as well as late stages of the malignancy. In three cases the MCB analysis gave hints of the presence of smaller or larger clones with tetrasomy 8. Tetrasomy 8 in myelocytic leukemias is correlated with a poor prognosis. The detection of tetrasomy by FISH in 3 of 13 cases where only trisomy 8 has been detected by GTG-banding remains noteworthy. It might be speculated that the tumor-promoting impact of trisomy 8 includes gene dosage effect ; however, not even a banding resolution of 510 bands per haploid karyotypes, as was achieved in the present study, could exclude the presence of submicroscopic mutations in a specific chromosome 8 region.

Cryptic aberrations; trisomy 8; molecular cytogenetics; FISH; multicolor banding; MCB; myelocytic malignancies

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