fluorescence in situ hybridization
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fluorescence in situ hybridization (FISH),
technique and adjunct method in cytogenetic analysis whereby a DNA probe is labeled with fluorescent dye and applied to interphase nuclei, binding to its complementary sequence and labeling a specific chromosome, which can then be visualized using a fluorescent microscope. FISH can show complex translocations and subtle deletions that are not readily discovered by routine karyotyping.
Molecular medicine Fluorescent In Situ Hybridization. A method for locating a segment of DNA on a chromosome. The DNA is labeled with a fluorescent dye and hybridized to a cytological preparation of chromosomes that has been denatured to allow nucleic acid hybridization between chromosomal DNA and the probe. The site of hybridization is determined by fluorescent microscopy. FISH is a hybrid of 3 technologies: cytogenetics, fluorescence microscopy, and DNA hybridization, which is used to determine cell ploidy and detect chromosome segments by evaluating interphase—non-dividing—nuclei; in FISH, fluoresceinated chromosome probes are used for cytologic analysis and cytogenetic studies, and to detect intratumoral heterogeneity. In genetics, FISH provides a physical mapping approach to detect hybridization of probes with metaphase chromosomes and with the less-condensed somatic interphase chromatin
DNA probes may be applied to cell preparations on a slide; if the complementary DNA sequence is present, it binds to DNA and can be detected by light microscopy; FISH labels probes nonradioactively either directly with fluorochromes, or indirectly with biotin and fluorochrome-labeled avidin, with digoxeginin and fluorochrome-labeled anti-digoxeginin, or others; the use of multiple band-pass filters allows simultaneous viewing of numerous probes for different chromosomal sequences labeled with different fluorochromes; FISH is useful in cytogenetic studies, where probes for particular chromosomes—e.g., chromosomes 13, 18, 21—or chromosomal regions—e.g., ABL and BCR genes in the Philadelphia translocation—can be used for the prenatal diagnosis of common aneuploidies or to detect early stages of lymphoproliferative disorders; FISH is as sensitive as other analytical techniques—e.g., conventional cytology and flow cytometry, used to diagnose transitional cell carcinoma of the urinary bladder
Pros FISH is simpler, less labor-intensive, and time-consuming—48 hours—than classic cytogenetics—karyotyping—2-3 weeks
Cons Only one question can be asked at a time, i.e., rather than asking ‘global issues’—e.g., what is the genetic composition of a population of cells
fluorescence in situ hybridization. See FISH.
fluor·es·cent in si·tu hy·brid·i·za·tion, fluorescence in situ hybridization (FISH) (flōr-es'ĕnt in sit'ū hī'brid-ī-zā'shŭn, flōr-es'ĕns)
A method used to determine the chromosomal location or expression pattern of genomic DNA or cDNA fragments. The piece of DNA to be mapped (the "probe") is labeled with a fluorescent dye and hybridized to a chromosome preparation or to a tissue section. The probe anneals to complementary DNA or RNA sequences. Examination of the chromosomes or tissue section under a fluorescence microscope reveals the number, size, and location of the target sequences.
fluorescence in situ hybridization (FISH)a type of IN SITU HYBRIDIZATION in which target nucleic acid sequences are located/sized in cells, by forming hybrids with fluorescently-labelled PROBES. Used, for example, to localize DNA sequences to chromosomes or parts of chromosomes in situ and to determine the distribution of particular sequences in cells and tissues by detecting fluorescence.
Fluorescence in situ hybridization (FISH)
A technique for diagnosing DiGeorge syndrome before birth by analyzing cells obtained by amniocentesis with DNA probes. FISH is about 95% accurate.
Mentioned in: DiGeorge Syndrome