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Application Of Comparative Genomic Hybridization In The Identification Of Chromosomal Abnormalities
- Aug 15, 2018 -

The Comparative Genomic Hybridization (CGH) technique was first created in 1992 by Kallioniemi. It is a molecular cytogenetic method that allows comprehensive detection and preliminary mapping of the entire genomic sequence copy number at all chromosomal levels. The basic principle is to label the normal genomic DNA and the test group DNA with different fluorescent dyes, and then hybridize with the normal human metaphase chromosome, and to determine the DNA copy number of the test group by detecting the relative intensity ratio of the two fluorescent signals on the chromosome. Change. This technique was originally applied to the study of solid tumors and is now widely used in blood system diseases, chromosomal diseases, prenatal diagnosis, and pre-implantation diagnosis. More and more studies have shown that CGH technology not only has the advantages of Fluorescent In Situ Hybridization (FISH) technology, but also overcomes the need to prepare chromosome-specific region probes and can only detect individual chromosomes or partial sites. limitation. In one experiment, the increase and decrease of the entire genomic DNA copy number of the sample to be tested can be detected, which greatly improves the comprehensiveness and accuracy of chromosomal diagnosis, and is an all-round detection method. Therefore, CGH technology as a new and effective molecular genetic method is being applied to the diagnosis of various chromosomal diseases by scholars at home and abroad. If CGH technology is applied to clinical diagnosis, this technique must first be established in the laboratory. To this end, the known sample cell DNA with chromosomal abnormalities is used to detect the sample to be tested, and the results consistent with cytogenetics are stabilized, and then the unknown specimen is detected. The incidence of extra small marker chromosomes (Small Supernumerary Marker Chromosomes) in neonates is about 0.14 ‰ to 0.72 ‰, and the incidence rate in the fetus is about 0.4 [%] - 1.5 [%]. In patients with labeled chromosomes, the variable clinical phenotype is due to the genetic material contained in the marker chromosome. The variability of marker chromosome morphology and its high incidence have brought great difficulties to genetic counseling, especially prenatal diagnosis. It is becoming more and more important to quickly and easily identify the source of marker chromosomes. In this experiment, the DNA of a constructed cell of a patient with an additional small marker chromosome of known origin was detected as a sample to be tested, and the results were consistent with molecular cytogenetic results. This proves that CGH technology, as a source of additional small marker chromosomes, is a quick and easy method to narrow the scope to a specific region by only one hybridization, and select the appropriate bacterial artificial chromosome (BAC) for the next step. Cloning provides an effective basis. On the other hand, by continuously optimizing the experimental conditions for the detection of known samples, the experimental technique is stabilized to provide a technical platform for further application of the technology to the clinic. At the same time, experiments have also proved that CGH technology is a simple and effective method for detecting DNA copy number changes.