What is Comparative Genomic Hybridization (CGH)?
Comparative Genomic Hybridization (CGH) is a molecular cytogenetic method for analyzing
genomic copy number variations (CNVs). It is particularly useful for identifying
genetic mutations that result in changes in the number of copies of DNA segments without requiring prior knowledge of specific chromosomal abnormalities.
How Does CGH Work?
In CGH, DNA from a test sample and a reference sample are labeled with different fluorescent dyes, usually green and red. These two DNA samples are then co-hybridized to a normal metaphase chromosome spread or a microarray. Fluorescence microscopy and imaging software are used to measure the intensity of the fluorescence signals. Deviations from the normal ratio of fluorescence intensities indicate areas of
copy number variations in the test DNA.
What Are the Limitations of CGH?
Despite its many advantages, CGH has some limitations. For instance, it cannot detect balanced rearrangements such as translocations and inversions. Furthermore, the resolution of CGH depends on the platform used; while array-CGH offers higher resolution, it may still miss very small mutations or low-level mosaicism.
Applications of CGH in Medical Research and Diagnostics
CGH has a wide range of applications in both medical research and clinical diagnostics. In cancer research, it is used to identify genetic mutations associated with tumorigenesis. In clinical diagnostics, CGH helps in the diagnosis of various genetic disorders, including developmental disorders and congenital anomalies. It is also used in prenatal diagnostics to detect chromosomal abnormalities in fetuses.Future Directions and Innovations
Advancements in technology are continually improving the capabilities of CGH. Emerging techniques like
next-generation sequencing (NGS) are being integrated with CGH to provide even more detailed genomic information. These innovations promise to enhance our understanding of genetic mutations and their role in disease, potentially leading to more targeted and effective therapies.
