fluorescent in situ hybridization
[floo-res-uhnt in sy-too hi-brid-ih-ZAY-shun]
also called FISH. A test that can help look at genes inside cells from a biopsy. It uses small deoxyribonucleic acid (DNA) probes labeled with special fluorescent dyes that only attach to certain parts of a gene to find specific DNA sequences. It can be used to diagnose, to evaluate prognosis (disease outlook), or to look at the remission of a disease. It is often used to count the number of HER2 genes in cancer cells. See also chromosome, cytogenetics, deoxyribonucleic acid, human epidermal growth factor receptor 2, remission.