Definition for View source for Fluorescence in situ hybridization (FISH)

FISH (fluorescence in situ hybridization) is a cytogenetic (meaning a branch of genetics that is concerned with the study of the structure and function of the cell) technique that is used to detect and localize the presence or absence of specific DNA sequences on chromosomes. FISH is a technique for mapping the location of genes onto chromosomes. The FISH map is a physical map, it shows the physical location of a gene on a chromosome. Genes can also be mapped using the frequency of recombination during meiosis. A recombination map calculates map distances between pairs of genes. Gene sequencing can also produce maps of genes that show not only their location but also the structure of the genes themselves. An advantage of the FISH technique is that it does not require information about other genes to map a single gene. All that is needed is a labeled probe that will bind to the gene.