Fluorescent In-situ Hybridization (FISH)

The FISH technique uses fluorescently labeled probes to target specific genes or a particular chromosomal region in order to detect abnormalities that cannot be identified by conventional banding methods. Some advantages of FISH include detection of microdeletions, chromosomal rearrangements, aneuploidy, and the ability to analyze nondividing cells. Recently, it has been widely used to validate microarray data by confirming amplification/gain or deletion/loss of chromosomal regions of interest. The drawback of FISH analysis is that it requires knowledge of the loci involved in an aberration.

The basic steps of FISH involve creating and labeling the probe, preparing slides with the desired target sample, hybridizing the probe to the sample, and visualizing the signal using a fluorescent microscope. FISH can be performed on cell nuclei or metaphase preparations that have been properly fixed and applied to slides, on “touch preps” (where a tissue is cut and then pressed onto a slide), or on paraffin-embedded or cryo-sectioned tissues.

Investigator responsibilities: 

1. Provide fixed, frozen, or actively growing cells, fresh or frozen tissues, or tissue section slides (formalin fixation for at least 24 hours and no longer than 48 hours is critical for tissue sections). 
2. Complete a project application and CTA agreement form.
3. For human samples, provide a copy of an IRB letter of approval, if applicable.