Fluorescence in situ hybridization (FISH)
Fluorescence in situ hybridization is a molecular cytogenetic technique that uses fluorescent probes which only bind to complementary nucleic acid sequence parts.
Exploiting a strand of DNA to hybridise specifically to another DNA strand. Using fluorescent labelled probes to attach to complementary sequences of a chromosome.
When looking to localize a specific nucleic acid sequence in a portion / section of the tissue for understanding a variety of chromosomal abnormalities and other genetic abberations.
A sample is taken from the patient. Oligionucleotide complementary to a region of interest is synthesized and chemically tagged with a flourescent probe. The sample is then chemically treated in order to make the cell membranes permeable. The probe is then added and only binds to complementary DNA under study. This way the specific target is diffeentiated from the rest of the sample population.
A technique where single-stranded DNA / RNA bind to complementary sequences. For example, Two single-stranded DNA molecules are able to reform a double helix DNA structure.
FISH is important as it allows fluroescent probes to bind to sections of nucleic acid sequence which are complimantary. Testing for the presence / absence of specific chromosome deletions, for example, Williams Syndrome.
Used to test for the presenece (or absence) of specific chromosome regions, usually when detecting small chromosome deletions.