Comparative Genomic Hybridization

Comparative Genomic Hybridization (CGH) is a molecular cytogenetic technique used to analyze the genomic imbalances or alterations between two different DNA samples. CGH allows for the detection of DNA copy number changes, such as deletions, amplifications, or rearrangements, across the entire genome. By comparing the DNA from a test sample to a reference sample, CGH provides insights into genetic variations associated with diseases and developmental disorders.

How does Comparative Genomic Hybridization (CGH) Work?

The CGH technique involves the following key steps:

  1. Sample Preparation: Genomic DNA is extracted from both the test sample (e.g., tumor cells) and the reference sample (e.g., normal cells). The DNA samples are then labeled with different fluorescent dyes, typically red and green, for easy differentiation during hybridization.
  2. Hybridization: The labeled test DNA and reference DNA are mixed together and applied to a microarray or a slide containing DNA fragments representing the entire genome. The DNA fragments on the microarray act as probes. The test and reference DNA hybridize to their complementary sequences on the microarray.
  3. Detection: The microarray is scanned to detect the fluorescent signals emitted by the hybridized DNA fragments. The intensity of the red and green signals reflects the relative copy number changes between the test and reference DNA samples. Software analysis is used to interpret the results and identify genomic imbalances.

Applications of Comparative Genomic Hybridization (CGH):

  1. Cancer Research: CGH plays a critical role in cancer genomics by identifying chromosomal aberrations and DNA copy number alterations associated with tumor development and progression. It aids in the identification of oncogenes, tumor suppressor genes, and potential therapeutic targets.
  2. Prenatal Diagnosis: CGH can be employed in prenatal testing to detect chromosomal abnormalities and genetic disorders in fetal DNA obtained through procedures like amniocentesis or chorionic villus sampling. CGH offers higher resolution and broader coverage compared to traditional techniques, allowing for the identification of subtle genetic changes.
  3. Constitutional Genetic Disorders: CGH assists in the diagnosis of genetic disorders caused by chromosomal imbalances, such as microdeletion or microduplication syndromes. It aids in identifying the genomic regions associated with the disorders, facilitating genetic counseling and personalized treatment plans.
  4. Research and Genomic Studies: CGH is widely used in research to study genomic variations and investigate disease mechanisms. It enables the identification of candidate genes involved in complex diseases and provides insights into the functional impact of copy number changes on gene expression.


Comparative Genomic Hybridization (CGH) is a powerful molecular cytogenetic technique that enables the comprehensive analysis of genomic imbalances and copy number changes. By comparing DNA samples, CGH provides valuable insights into genetic variations associated with diseases, developmental disorders, and cancer. At Hugenta, we harness the potential of CGH to unravel the genomic landscape and advance our understanding of the intricate world of genetics. Join us on this enlightening journey as we explore the transformative impact of Comparative Genomic Hybridization (CGH) on genetic research and diagnostics.

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