FISH is a molecular detection technique that uses fluorescently-labeled DNA probes to hybridize to the complimentary regions with the specimen’s DNA. The probes utilized include a chromosome enumerating probe (CEP) and a loci-specific identifier (LSI) probe. The CEP is designed to bind to repetitive sequences within a particular chromosome to detect the number of copy numbers present. The LSI probe is designed to bind to the loci of a specific target region or gene. LSI probes are often used to detect the loss or gain of a specific gene or loci regions. Visualization is achieved by the use of fluorescent chromogens which can be visualized using specialized polarizing microscope equipment and filters.