Used to identify the presence and location of a region of DNA or RNA within morphologically preserved chromosome preparations, fixed cells or tissue sections
FISH: Limitations
➢ Probe design requires knowledge of specific chromosomal abnormalities to be studied
➢ Cutoff signals may be different among laboratories ➢ Processing errors, imperfect hybridization, non-specific
• Special telomeric probes specific to individual chromosomes have been designed
• Probe is based on the TTAGGG repeat present on all human telomeres Application in cytogenetics - can detect submicroscopic deletions and cryptic translocations of genes associated with unexplained mental retardation and miscarriages
➢ Allows simultaneous interrogation of multiple cytogenetic signatures
➢ Can be used either in bulky tumors or tumors where the malignant component contributes to a small proportion of the overall cellular population
