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
non-dividing cells. Recently, it has been widely used to validate micro-array 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, or
on paraffin-embedded tissues.