Fluorescence in situ hybridization (FISH) permits nucleic acid sequences to be detected directly on metaphase chromosome or interphase nuclei.
The FISH assay is a powerful tool in visualizing simple and complex chromosomal rearrangements at single-cell resolution.
The FISH assay provides cell-based diagnosis and monitoring of abnormal clones in hematological malignancies.
FISH provides rapid diagnosis in subset of constitutional disorders and complements microarray findings.
Emerging research applications for FISH are providing novel insights into chromosome biology.
Fluorescence in situ hybridization (FISH) has proven to be a key tool in diagnostic molecular cytogenetics along with research applications in chromosome and cell biology. FISH allows the ability to contextually define and localize nucleic acid sequences directly on human metaphase chromosomes and interphase nuclei. From its earliest inception in the late 1960s
to the first use of nonradioisotopic techniques , the impact of FISH has been vast. In particular, in cytogenetics, FISH has provided diagnostic and prognostic information for prenatal and constitutional disorders as well as hematological malignancies, and solid tumors. FISH has also complemented genomic studies, such as chromosomal microarray (CMA)
. Research applications in FISH technology have evolved to include the use of superresolution microscopy systems for visualizing intranuclear chromosomal organization, and various methods have been used for improving probe labeling efficiency.
As either a stand-alone diagnostic method or a molecular method coupled with standard karyotyping, FISH has significantly improved the resolution and therefore detection of numerical and structural chromosomal abnormalities beyond the light microscope. A distinct advantage of FISH is the application of fluorescent probes to nondividing cells obtained from cell suspension or paraffin-embedded tissues. FISH can detect tumor heterogeneity for both major and minor clonal abnormalities. The use of multicolor probes enables the localization and detection of multiple targets simultaneously.
FISH performed with probes comprising a lymphoma test panel ( BCL2 , BCL6 , MYC ) can identify “double-hit” lymphoma in cases with a pathologic diagnosis of diffuse large B-cell lymphoma
. FISH is also used to confirm chromosomal rearrangements identified by standard karyotyping or other molecular methods, including CMA. Parental confirmation of copy number gain or loss identified in a proband may be performed with labeled bacterial artificial chromosome DNA probe constructs that capture the copy number abnormality and detect its presence or absence in parental DNA. FISH remains a critical tool for detection and monitoring of genomic abnormalities across the spectrum of prenatal, constitutional, and neoplastic disease.