Cross-species color banding in ten cases of myeloid malignancies with complex karyotypes

Cross-species color banding is a multiple-color fluorescence in situ hybridization (FISH) technique using probes developed from other animal species. Hybridization to human metaphases produces color banding patterns specific for each homologous chromosome pair. The technique has been evaluated in a complementary manner with G-banding and chromosome painting in a series of 10 myeloid malignancies with complex or unresolved karyotypes. Color banding detected the majority of chromosomal abnormalities, which had been identified by G-banding and in each case revealed chromosomal changes that G-banding had not identified. Painting was necessary to confirm these abnormalities due to the limitation of only seven colors in the color-banded karyotype. At the same time, painting fortuitously uncovered cryptic abnormalities in 6 of 10 cases that had not been detected by color banding. Insertions were visible by painting only. This study has demonstrated that in the analysis of complex karyotypes, the application of color banding revealed the involvement of the long arm of chromosome 3, indicating a poor risk, in two cases not identified by G-banding. Therefore, these techniques applied together have revealed cryptic chromosomal abnormalities with prognostic significance, which in some cases may have implications for patient management.