Fluorescence in situ hybridization (FISH) is a powerful molecular technique that is used to determine the status of a gene in human cells. Genes are the basic hereditary units comprised of deoxyribonucleic acid (DNA). DNA resides in the nucleus in the form of chromosomes. There are 46 chromosomes in the human cell.
FISH uses fluorescently labeled DNA probes to target a specific sequence of DNA that may represent a gene or a particular sequence of a gene. FISH is useful for detection of genetic aberrations, such as the amplification, translocation, or deletion of a gene. This technique is used for many purposes, including caring for cancer patients from initial diagnosis to evaluation of remission. The quantitative nature of this test makes it more objective. FISH testing may also be used to qualify patients for chemotherapy or to predict their prognosis.
Fresh preparations such as cytospins and touch preps or formalin-fixed, paraffin-embedded (FFPE) tissues may be used.