Array Comparative Genomic Hybridization (Array CGH) is a powerful genomic tool that helps detect chromosomal imbalances such as deletions, duplications, and amplifications in the DNA. Unlike traditional techniques like karyotyping, Array CGH provides a high-resolution, genome-wide analysis of copy number variations (CNVs), enabling the detection of submicroscopic genetic changes that may be involved in diseases like cancer, come funziona array cgh developmental disorders, and other genetic conditions. Here’s a step-by-step explanation of how Array CGH works:
1. DNA Extraction
- The first step in the Array CGH process involves extracting DNA from both the test sample (e.g., patient DNA) and a reference sample (usually from a healthy individual or control).
2. DNA Labeling
- The next step is the labeling of both DNA samples with fluorescent dyes to differentiate between the test and reference samples. Typically:
- Test DNA is labeled with a red dye.
- Reference DNA is labeled with a green dye.
- These dyes help identify and compare the DNA samples during hybridization and scanning.
3. Hybridization to a Microarray
- The labeled test and reference DNA are mixed together and then hybridized onto a microarray. A microarray is a chip that contains thousands of DNA probes, which are short DNA sequences that correspond to specific regions of the genome.
- The probes on the microarray bind to the complementary sequences in the test and reference DNA samples. This process allows researchers to examine specific areas of the genome for copy number variations.
4. Scanning and Signal Detection
- After hybridization, the microarray is scanned using a fluorescence scanner. The scanner detects the intensity of the red and green fluorescence signals, which are directly related to the amount of DNA from the test and reference samples at each probe location.
- In regions where there is no imbalance, the red and green signals will be of equal intensity, indicating a normal copy number.
- If there is a duplication in the test DNA (extra copies of DNA), the red signal will be stronger.
- If there is a deletion in the test DNA (missing DNA), the green signal will be stronger.
5. Data Analysis and Interpretation
- The intensity of the fluorescence signals is analyzed to identify regions of copy number variation (CNVs) in the test DNA. These imbalances are highlighted and can be visualized as a genomic map.
- A dominant red signal indicates a duplication, while a dominant green signal suggests a deletion.
- The identified CNVs can be further analyzed to determine if they are linked to any genetic diseases, cancers, or other conditions.
6. Result Interpretation and Clinical Applications
- Once the data is processed, the results are interpreted to detect genetic abnormalities. This analysis can provide critical insights into potential genetic causes of a patient’s condition.
- Array CGH is used in clinical diagnostics, cancer research, prenatal screening, and the study of developmental disorders, helping clinicians make more accurate diagnoses and treatment decisions.
Conclusion:
Array CGH is a revolutionary technique for detecting chromosomal imbalances that might otherwise go unnoticed. By comparing the test DNA with a reference, the technique identifies genomic changes such as deletions and duplications, offering high-resolution insights into genetic disorders. This method is essential in modern genetics, allowing for the detection of subtle genetic abnormalities that can significantly impact health.
