What is the Difference Between FISH and CGH?

FISH (Fluorescence In Situ Hybridization) and CGH (Comparative Genomic Hybridization) are both molecular cytogenetic techniques used to detect chromosomal abnormalities, deletions, duplications, and rearrangements. However, they differ in several aspects:

1. Technique: FISH is an in situ hybridization procedure that uses fluorescent probes to detect specific DNA sequences, while CGH is a molecular hybridization technique that detects alterations in the genomic DNA.
2. Resolution: FISH has limited resolution, while aCGH (array-based CGH) offers higher resolution, allowing for the detection of smaller changes in the genomic DNA.
3. Probe Design: FISH requires prior knowledge of the target abnormality to design probe sequences, while CGH does not require prior knowledge.
4. Probes: In FISH, multiple colored probes can be hybridized to the experimental sample, but the number of different probes is limited to the number of different colors available. CGH, on the other hand, can probe thousands of DNA targets simultaneously.
5. Detection: FISH uses a fluorescence microscope to detect the binding of the probe to the chromosome, while CGH uses array technology to detect changes in the genomic DNA sequence.

In summary, FISH is a more targeted technique that requires prior knowledge of the specific DNA sequence, while CGH is a more global approach that can detect a wide range of genomic alterations without prior knowledge of the target abnormality. Both techniques rely on nucleic acid hybridization and the use of designed probes, but they differ in terms of resolution, probe design, and detection methods.

Comparative Table: FISH vs CGH

FISH (Fluorescence In Situ Hybridization) and CGH (Comparative Genomic Hybridization) are two molecular cytogenetic techniques used to detect chromosomal abnormalities, such as deletions, duplications, and rearrangements, which can lead to genetic diseases like cancer, infertility, and Down syndrome. Here is a table comparing the differences between FISH and CGH:

In summary, FISH is a targeted technique that requires prior knowledge of the target abnormality and uses fluorescent probes to detect specific DNA sequences, while CGH is a broader technique that assesses copy number variation across the entire genome without the need for prior knowledge of the target abnormality.