Fluorescence in situ hybridization (FISH)

August 29, 2023

What is fluorescence in situ hybridization?

Fluorescence in situ hybridization (FISH) is a molecular test pathologists perform to learn more about the genetic material in a cell. FISH is commonly used to look for genetic changes in tumours.

How does fluorescence in situ hybridization work?

Fluorescence in situ hybridization (FISH) uses a fluorescent probe that has been designed to stick to a unique segment of DNA (the target). FISH probes are called fluorescent because they only produce a colour when they are exposed to certain types of light. As a result, pathologists need to use a special type of microscope that can produce specific types of light and detect the colour coming from the probe.

The results are captured in an image on a computer for further analysis. When the probe finds a change in the location of the target DNA, the result is called a translocation. When the probe finds a change in the total amount of target DNA, the result is called an amplification or deletion depending on the type of change identified.​

Fluorescence in situ hybridization
Fluorescence in situ hybridization (FISH). The probes are seen as green and red dots within the blue nucleus of the cell.

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