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Array Comparative Genomic Hybridization (Array CGH) is a sophisticated technique used to identify chromosomal imbalances such as deletions, duplications, and amplifications in DNA. Unlike traditional cytogenetic methods, which are limited in resolution, Array CGH allows for the detection of submicroscopic genetic changes that can be crucial in understanding genetic disorders, cancer, and developmental diseases. Here’s an explanation of how Array CGH works:
1. DNA Extraction
The process starts with extracting DNA from both the test sample (usually a patient or subject sample) and a reference sample (typically from a healthy individual or control).
2. Labeling the DNA
- The extracted DNA from both samples is labeled with different fluorescent dyes:
- Test DNA is typically labeled with a red fluorescent dye.
- Reference DNA is labeled with a green fluorescent dye.
- These labels allow for the differentiation between the two DNA samples during the hybridization process.
3. Hybridization to a Microarray
- The labeled test and reference DNA are mixed together and hybridized onto a microarray. The microarray consists of thousands of DNA probes, each corresponding to specific regions of the genome.
- The probes on the microarray are designed to bind to complementary sequences in the test and reference DNA samples, enabling the detection of copy number variations (CNVs).
4. Scanning the Microarray
- After hybridization, the microarray is scanned using a fluorescence scanner that detects the fluorescent signals from the labeled DNA.
- The fluorescent intensity of the red (test DNA) and green (reference DNA) signals is recorded:
- Equal intensity indicates no genetic imbalance.
- Red signal dominance indicates a duplication in the test sample (extra copies of genetic material).
- Green signal dominance suggests a deletion in the test sample (missing genetic material).
5. Data Analysis and Interpretation
- The data collected from the fluorescence scanner come funziona array cgh is processed and analyzed to identify copy number variations (CNVs) in the genome.
- Regions with a higher red intensity than green suggest a duplication, while higher green intensity suggests a deletion.
- The results are visualized as a genomic map, which highlights the regions of the genome with imbalances.
6. Clinical Implications
- Array CGH provides valuable information that can be used to diagnose genetic disorders, cancers, and other conditions related to chromosomal abnormalities.
- It helps researchers and clinicians understand the genetic basis of various diseases by identifying genetic imbalances that might not be detected by traditional methods like karyotyping.
Conclusion:
Array CGH works by comparing the test and reference DNA using a microarray and fluorescent labeling. The technique detects submicroscopic genetic imbalances such as deletions and duplications by analyzing differences in fluorescent signal intensities. This provides a high-resolution method for identifying genetic abnormalities, making it an essential tool in genetic research, diagnosis, and treatment planning.
