Fluorescence in situ hybridization (FISH) utilizes molecular biology techniques to detect the presence or absence of and enumerate specific region of the genome using fluorescently labeled pieces of DNA (probes). Unlike most other techniques used to study chromosomes, FISH does not require actively dividing cells. This adds flexibility and increases the ability to identify and characterize cytogenetic abnormalities.
FISH has applications in all aspects of clinical cytogenetics including: prenatal aneuploidy screening and sex determination; diagnosis of microdeletion syndromes; investigation of unexplained mental disability; and malignancy diagnosis, prognosis, and remission status. Probes may be used alone or in combinations of genes and/or regions specific to a particular disease. FISH offers limited information specific to the DNA sequence contained in the probe. Currently, FISH is routinely used in clinical practice for diagnosis, prognosis and to select appropriate therapies for patients with diseases such as hematologic malignancies.