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Nuclear Molecular Genetics Technology

Nuclear Molecular Genetics Technology.  7 important points on Nuclear Molecular Genetics Technology. 

1. The meaning of cytogenetics technology

Cytogenetics technology mainly refers to the analysis of the relationship between the number and structure of chromosomes and human diseases by preparing chromosome specimens.

2.  Cell and molecular genetics technology

The combination of modern molecular biology technology and cytogenetics technology has formed cellular and molecular genetics technology. Among them, the more mature and practical technologies are: ①Fluorescence in situ hybridization (FISH); ②Comparative genome hybridization (CGH).

3. The principle of fluorescence in situ hybridization

The principle of fluorescence in situ hybridization is to use fluorescein-labeled DNA probes to hybridize with the tissues in the sample (cell smear or thick paraffin section), and display a specific segment of the corresponding chromosome or the entire chromosome under a fluorescence microscope.

These probes generally contain a nucleotide sequence of 1×101-1×106 bases, and can be used for analysis of interphase cells and metaphase cells. There are generally several types of probes, such as centromeric probes, whole chromosome probes, and site-specific probes, which are used for different purposes.

The site-specific probes for detecting chromosomal translocations are divided into fusion probes and separation probes. Different fluorescently labeled probes show different colors to detect chromosomal changes.

4.Application of fluorescence in situ hybridization

Fluorescence in situ hybridization (FISH) can effectively detect abnormalities in the structure and number of chromosomes, so it is suitable for chromosome translocation, deletion and amplification.

⑴The application of centromere probe: It can detect the gain and loss of chromosomes in neoplastic and non-neoplastic diseases, for example: +12 in B-chronic lymphocytic leukemia/small lymphocytic lymphoma, which is generally used in prenatal examinations Site-specific probes assess chromosomal abnormalities and do sex identification.

(2) Application of site-specific probes: It can be used for the diagnosis and prognosis judgment of hematopoietic tissue tumors and soft tissue sarcomas.

FISH analysis and detection can also be used to detect HER2/neu gene amplification in breast cancer, EGFR gene amplification in multiform glioma, MYCN gene amplification in neuroblastoma, and detection of chromosome specific site deletions. To diagnose the disease and estimate the prognosis.

5. The principle of comparative genomic hybridization (CGH)

The principle of comparative genomic hybridization is to extract DNA from tumor cells and normal lymphocytes respectively, and then stain them with different fluorescent dyes and then hybridize. Compare the entire genome on all chromosomes in tumor cells and normal cells to see if there is an entire chromosome or a certain chromosome. The increase or decrease of these sections.

6. Compare the differences between genomic hybridization and traditional cytogenetic analysis methods

The main difference between comparative genome hybridization and traditional cytogenetic analysis methods is that comparative genome hybridization only relies on the available genomic tumor DNA and does not require metaphase cells or specific probes; comparative genome hybridization can be obtained from fresh tissue or paraffin. DNA is extracted from the embedded tissue for testing.

7.  the application of comparative genomic hybridization

Comparative genome hybridization is mainly used to detect the deletion and duplication of chromosomes and their segments, that is, the loss, gain and gene amplification of chromosomes.

However, comparative genome hybridization cannot be used to detect chromosomal translocations, inversions, ploidy changes, and point mutations.

(source:internet, reference only)

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