How is FISH used in Cancer Diagnosis?
FISH is extensively used in the diagnosis and classification of various types of
cancers. It helps in identifying genetic abnormalities such as
gene amplifications, deletions, or translocations that are often associated with specific types of cancer. For instance, the detection of the
HER2/neu gene amplification in breast cancer using FISH can help in determining the appropriate targeted therapy.
Sample Preparation: The biological sample, which could be tissue, blood, or bone marrow, is prepared and fixed onto a microscope slide.
Probe Labeling: Fluorescent probes specific to the DNA sequences of interest are synthesized and labeled with fluorescent dyes.
Hybridization: The labeled probes are applied to the sample, where they hybridize with their complementary DNA sequences.
Washing: Excess probes are washed away to reduce non-specific binding.
Visualization: The hybridized probes are visualized using a fluorescence microscope, allowing for the detection of specific genetic abnormalities.
Centromeric Probes: These target the centromere regions of chromosomes and are useful for detecting aneuploidy.
Telomeric Probes: These target the telomere regions and can be used to study telomere length and integrity.
Whole Chromosome Probes: These are used to paint entire chromosomes and are useful for identifying chromosomal translocations.
Locus-Specific Probes: These target specific gene loci and are used to detect specific gene amplifications or deletions.
High Sensitivity and Specificity: FISH can detect even small genetic changes with high accuracy.
Rapid Results: The FISH procedure can be completed relatively quickly, providing timely information for diagnosis and treatment decisions.
Versatility: FISH can be used on a variety of sample types, including fresh, frozen, and paraffin-embedded tissues.
Quantitative Analysis: FISH allows for the quantification of gene amplifications and deletions, aiding in the assessment of cancer prognosis and response to therapy.
Technical Complexity: The procedure requires specialized equipment and technical expertise.
Cost: The cost of FISH can be relatively high due to the need for fluorescent probes and specialized imaging equipment.
Resolution Limitations: FISH may not detect very small genetic alterations that are beyond its resolution capabilities.
Probe Availability: The availability of specific probes may limit the range of genetic abnormalities that can be detected.
