Fluorescent In Situ Hybridisation ( FISH)
-Technique for the detection of specific genetic information on a morphologically intact tissue using fluorescent probes.
-The fluorescent probes are added to cells usually arrested in the metaphase stage of cell division.
Types of FISH:
1)Chromosomal painting:
Each chromosome is identified by using a different colour of the fluorescent probe, however each chromosome does not have a unique color. Since the fluorescent dyes are limited.
2)Multicolor FISH:
23 distinct fluorescent colours are made by mixing 5 flurophores.
Thus each chromosome is identified by a unique color. It is also known as spectral karyotyping (SKY).
It offers various advantages such as:
:-Detects structural and numeric abnormalities in chromosomes.
:-Detects gene amplification and subtle microdeletions
:-Maps a newly isolated gene to its correct chromosomal loci
But this process requires prior knowledge of the gene and chromosomes.
3)Interphase FISH
It is a rapid procedure of FISH, wherein growing cells are not needed. It is used in prenatal diagnosis ad in tumour diagnosis.