Multiplex Fluorescence In Situ Hybridization and Cross Species Color Banding of a Case of Chronic Myeloid Leukemia in Blastic Crisis with a Complex Philadelphia Translocation

Exciting new techniques in molecular cytogenetics—namely, spectral karyotyping, multiplex fluorescence in situ hybridization (M-FISH), and cross species color banding—have been recently developed. An increasing number of reports demonstrate the success of these procedures in providing additional cytogenetic information—identifying marker chromosomes and revealing the presence of previously undetected chromosomal changes. However, these procedures have their limitations, and their absolute sensitivity in the accurate identification of subtle chromosomal abnormalities remains to be established. M-FISH and color banding have been applied to a case of chronic myeloid leukemia with a complex Philadelphia translocation involving chromosomes 9, 17, and 22, which had initially been identified from G-banded chromosome analysis. The abnormalities were confirmed by chromosome “painting” and specific probes. Although M-FISH and color banding revealed no additional cryptic chromosomal changes, this study has clearly demonstrated the success of these multiple color FISH approaches in the accurate characterization of a complex rearrangement with subtle abnormalities.