Simultaneous detection of multiple genetic aberrations in single cells by spectral fluorescence in situ hybridization

Spectral fluorescence in situ hybridization (S-FISH) is a novel molecular c ytogenetic approach that detects multiple disease-specific chromosomal aber rations in interphase nuclei using combinatorial fluorescence and digital i maging microscopy. A panel of six centromeric probes for chromosomes 7, 8, 9, 10, X, and Y, using a unique two-dye combination of four fluorophores, w as developed to assess ploidy in breast tumors, bladder washings, and leuke mia. Validation of S-FISH was performed by classic cytogenetics when metaph ases were available or by standard fluorescence in situ hybridization (FISH ) analyses. S-FISH identified clonal aberrations in newly diagnosed breast tumors and recurrent bladder cancer and revealed minimal residual disease i n hyperdiploid acute lymphocytic leukemia, providing "proof of concept." Li ke standard FISH, aberrations were identified in poor growth/no growth spec imen at the single cell level; however, S-FISH provided increased sensitivi ty over standard FISH by surveying six genetic targets instead of one or tw o. Disadvantages of the current assay include labor intensive screening and interpretative challenges with signal overlap in highly aneuploid samples and focal plane distortions. S-FISH appears to be a sensitive oncology assa y with significant clinical application For early detection of new or reeme rging clones, allowing for earlier therapeutic intervention and development of probe panels for individualized therapy.