Array Comparative Genomic Hybridization (Array CGH) is a powerful molecular diagnostic tool used to detect chromosomal imbalances such as deletions, duplications, and amplifications in DNA. Unlike traditional techniques like karyotyping, which only detect larger chromosomal abnormalities, Array CGH offers high-resolution analysis, enabling the detection of submicroscopic changes that can play a critical role in genetic diseases and cancer. Here’s a breakdown of how Array CGH works:

1. DNA Extraction

  • The process begins with the extraction of DNA from both the test sample (e.g., patient DNA) and the reference sample (often from a healthy individual or control).

2. Labeling of DNA

  • The DNA from both samples is labeled with different fluorescent dyes:
    • Test DNA is typically labeled with a red dye.
    • Reference DNA is labeled with a green dye.
  • These labels allow the test and reference DNA to be distinguished during analysis.

3. Hybridization onto a Microarray

  • The labeled DNA samples are mixed and then hybridized onto a microarray, which is a small chip containing thousands of DNA probes. These come funziona array cgh probes represent specific regions of the genome.
  • The probes are designed to bind to complementary sequences in the DNA samples, allowing researchers to identify areas where copy number variations (CNVs)—gains or losses of genetic material—are present.

4. Scanning and Signal Detection

  • After hybridization, the microarray is scanned with a fluorescence scanner that detects the intensity of the red and green signals.
  • Equal intensity of red and green signals indicates a normal copy number of genetic material.
  • Red signal dominance (more test DNA) suggests a duplication in the test sample.
  • Green signal dominance (more reference DNA) indicates a deletion in the test sample.

5. Data Analysis and Result Interpretation

  • The fluorescence data is analyzed to identify regions of genomic imbalance. The results are typically displayed as a genomic map that highlights areas of deletions, duplications, or amplifications.
  • Clinicians and researchers interpret these findings to correlate the detected genetic changes with potential diseases or disorders, including cancer and genetic syndromes.

Conclusion:

Array CGH is a sensitive and high-resolution technique that allows for the detection of submicroscopic chromosomal changes in a patient’s DNA. By comparing the test and reference DNA on a microarray, Array CGH can uncover hidden genetic imbalances that may contribute to diseases, offering valuable insights for diagnosis, research, and treatment planning.