New chromosomal breakpoints in non-Hodgkin's lymphomas revealed by spectral karyotyping and G-banding

Chromosomal rearrangements in short term cultures from nine cases of non-Hodgkin's lymphomas (NHL) were characterized by G-banding, spectral karyotyping (SKY), and fluorescence in situ hybridization (FISH). Eight of the nine cases showed complex karyotypes with chromosomal aberrations which, in most cases, could not be fully characterized by traditional G-banding analysis alone. Karyotypic abnormalities of special interest were marker chromosomes and chromosomes with added unidentified chromosomal material, as previously non-identified chromosomal translocations were hidden behind these aberrations. SKY and FISH analysis, as a complement to banding analysis, significantly improved the karyotypes in seven of the nine cases and unveiled 21 previously unidentified rearrangements with novel translocation breakpoints. Traditional G-banding alone revealed seven new rearrangements, which were all confirmed by SKY. None of these new aberrations occurred as single clonal rearrangements but as parts of complex karyotypes. Nevertheless, the chromosomal break-point regions identified should be considered as potential hot spots for genes involved in the tumorigenesis of the malignancy.