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FISH can also be used to detect diseased cells more easily than standard Cytogenetic methods, which require dividing cells and requires labor and time-intensive manual preparation and analysis of the slides by a technologist. FISH, on the other hand, does not require living cells and can be quantified automatically, a computer counts the ...
CISH is similar to FISH in that they are both in situ hybridization techniques used to detect the presence or absence of specific regions of DNA. [1] However, CISH is much more practical in diagnostic laboratories because it uses bright-field microscopes rather than the more expensive and complicated fluorescence microscopes used in FISH.
Quantitative Fluorescent in situ hybridization (Q-FISH) is a cytogenetic technique based on the traditional FISH methodology. In Q-FISH, the technique uses labelled (Cy3 or FITC) synthetic DNA mimics called peptide nucleic acid (PNA) oligonucleotides to quantify target sequences in chromosomal DNA using fluorescent microscopy and analysis software.
The standard resolution varies between 1 and 5 Mb, but can be increased up to approximately 40 kb by supplementing the array with extra clones. However, as in conventional CGH, the main disadvantage of array CGH is its inability to detect aberrations that do not result in copy number changes and is limited in its ability to detect mosaicism. [14]
To detect hybridization of the probe to its target sequence, the probe is tagged (or "labeled") with a molecular marker of either radioactive or (more recently) fluorescent molecules. Commonly used markers are 32 P (a radioactive isotope of phosphorus incorporated into the phosphodiester bond in the probe DNA), digoxigenin , a non-radioactive ...
These tests can accurately identify trisomy 13, trisomy 18, and trisomy 21. [1] FISH is capable of providing a limited karyotype and, along with the aforementioned trisomies, can also detect aneuploidies in the X and Y sex chromosomes. [5]
Flow-FISH was first published in 1998 by Rufer et al. [11] as a modification of another technique for analyzing telomere length, Q-FISH, that employs peptide nucleic acid probes [12] of a 3'-CCCTAACCCTAACCCTAA-5' sequence labeled with a fluorescin fluorophore to stain telomeric repeats on prepared metaphase spreads of cells that have been treated with colcemid, hypotonic shock, and fixation to ...
It entails sampling of the chorionic villus (placental tissue) and testing it for chromosomal abnormalities, usually with FISH or PCR. CVS usually takes place at 10–12 weeks' gestation, earlier than amniocentesis or percutaneous umbilical cord blood sampling. It is the preferred technique before 15 weeks. [2]