Fluorescence in situ hybridization (FISH) – a relatively new cytogenetic technique - is a DNA hybridization-based technique that generally uses directly-labeled fluorescent DNA probes to target specific chromosomal locations within the nucleus, resulting in colored signals that can be detected using a fluorescent microscope. Alternatively, FISH probes can be indirectly labeled with reporter molecules that are subsequently detected by fluorescent antibodies or other affinity molecules.
FISH is applied to detect genetic aberrations including
- Characteristic gene fusions or translocations
- Characteristic gene rearrangements
- Partial or complete loss of chromosome
- Presence of an abnormal number of chromosomes in a cell
Hence FISH can be applied to diseases covering genetic etiologies as well as cancer –both hematological and solid tumors. Additionally FISH can be applied to basic research applications like gene mapping or in discovery based assays like elucidation of novel oncogenes. Furthermore it can be used to aid in novel biomarker discovery. FISH has now been expanded to screen/analyze whole genome in one-go (in single experiment) using multicolor whole chromosome probe techniques like multiplex FISH or spectral karyotyping.