It is an advanced cytogenetic technique which can be carried out on both interphase cells and metaphase chromosomes.
FISH helps to:
- Detect microdeletions beyond resolution of routine cytogenetics
- Identify extra material of unknown origin.
- Determine a simple deletion or a subtle or complex rearrangement.
- Detect specific rearrangements in certain cancers
A spectral karyotyping image showing fluorescent labelling to distinguish all the 23 pairs of chromosomes
A metaphase FISH showing signals on specific chromosome 13 regions with red and green signal
An interphase FISH showing the exchange of chromosomal material on Chromosomes 9 and 22(Red and Green) to give a BCR-ABL fusion(Yellow)
An interphase FISH showing three red, two green and two blue signals indicating extra chromosome 21 (Down syndrome).
For FISH the region of chromosome to be evaluated needs to be specified and a appropriate probe to be selected unlike Cytogenetics where all chromosomes can be assessed simultaneously.