From the Guidelines
FISH modification should prioritize the use of multicolor FISH for detecting several genetic targets in a single experiment, as it enhances resolution, sensitivity, and multiplexing ability, making it more versatile for various genetic analyses 1.
Key Considerations
- The choice of probes will be dictated by the increasingly accurate and scientifically based map of the human genome.
- Probe use may be considered adjunctive when confirming or characterizing an abnormality detected by routine cytogenetics or other molecular methods.
- FISH may be used in diagnostic stand-alone assays when microdeletions are submicroscopic.
Technical Considerations
- The demonstration of scientific/clinical validity will be reasonably straightforward and the demonstration of the analytical validity of the test system used should be fairly direct.
- Establishing the relationship of a gene and its mutations or variations to a particular disease does not establish the magnitude or strength of the relationship.
Clinical Applications
- FISH based testing has broad clinical applications, including determining the extent of genomic imbalance originally identified by another testing methodology.
- The use of FISH may be quite generic and adjunctive, or highly specific, as in microdeletion testing.
- FISH may be used to confirm or characterize an abnormality detected by routine cytogenetics or other molecular methods, and may be used in diagnostic stand-alone assays when microdeletions are submicroscopic 1.
From the Research
FISH Modification
- FISH (Fluorescence In Situ Hybridization) is a technique used to detect genetic alterations, such as gene fusions, copy number gain, and amplification, in cells 2.
- In the context of triple-negative breast cancer, FISH has been used to investigate the frequency of NTRK gene aberrations, including fusions, gene copy number gain, and amplification 2.
- However, FISH has been shown to have limitations, such as a high false-positive rate for the detection of fusions, and molecular testing is mandatory to confirm the results 2.
- Other studies have used FISH in combination with next-generation sequencing (NGS) to detect gene mutations and chromosomal abnormalities in hematopoietic progenitors in chronic lymphocytic leukemia 3.
- A comparison of FISH, NGS, and DNA methylation microarray for copy number variation assessment in gliomas found that FISH demonstrated relatively low concordance with NGS and DNA methylation microarray in detecting certain parameters, such as EGFR, CDKN2A/B, and chromosome 7 4.
- The choice of technique depends on the specific application and the type of genetic alteration being detected, with FISH being a useful tool for detecting specific genetic alterations, but requiring confirmation with molecular testing 2, 3, 4.