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Partial deletion or duplication is a common chromosomal imbalance aberrations, often associated with congenital multiple malformations, growth retardation and mental retardation related. The traditional method of chromosome G-banding karyotype analysis technology can detect abnormal the entire chromosome number and structure, but its resolution is limited and for fragment length less than 5Mb imbalance distortion is difficult to detect. Fluorescence in situ hybridization (fluorescence in situ hybridization, FISH) can verify that known or suspected submicroscopic deletions and duplications, but can not be diagnosed without any definite banding patterns unknown chromosomal abnormalities. 24 color spectrum probes with metaphase chromosomes hybridization, spectral karyotyping (the Spectral karyotypin, SKY) can determine the chromosomal ectopic source of marker chromosomes, but you can not make a diagnosis for the same chromosome internal exception. Micro-array comparative genomic hybridization (array-based comparative genomic hybridization, array-CGH or aCGH) is a recently developed an efficient molecular karyotype analysis technology, its advantage lies in avoiding the metaphase chromosomes, directly at the DNA level diagnosis . Array-CGH through time hybridization experiments to genome-wide DNA copy number variation (copy number variants, CNVs) for high-throughput, high-resolution, quickly and accurately detects the amount of DNA copy number, and can a DNA sequence variations accurately locate the chromosomes, and therefore most suitable for the diagnosis of chromosome micro-deletions or duplications. Array-CGH technology chromosome diagnosis to the level of the gene genotype - phenotype relationship analysis to guide clinical genetic counseling, MD, an accurate assessment of the condition and prognosis. This study is the first application of Array-CGH technology diagnosis and prenatal diagnosis of chromosomal imbalance distortion cases. First, the purpose (1) Establish the micro-array comparative genomic hybridization (array-based comparative genomic hybridization, array-CGH or aCGH), Array-CGH technology in the diagnosis and prenatal diagnosis of unbalanced chromosome aberrations. Explore the array-CGH diagnostic accuracy and sensitivity of the unbalanced chromosome aberrations. Explore the aCGH technology and G-banding, FISH, SKY technology, as well as C-banding, and other banding technique in the diagnosis of unbalanced chromosome aberrations in how to effectively combine ideal laboratory diagnostic criterion. Second, the objects and methods. Research object, select the period January 2008 to December 2009 in Guangzhou Women and Children's Medical Center eugenics Perinatal Institute of Genetic Counseling outpatient or outside the hospital referral line chromosome 21 cases. Including peripheral blood in 19 cases, 1 cases of prenatal diagnosis of amniotic fluid, umbilical cord blood 1 cases. 21 cases, 4 cases of normal controls; 17 cases of suspected chromosomal abnormalities in patients, but failed to confirm the diagnosis by conventional G karyotype analysis. 2, the method (1) a sample of 21 cases operated by SNP chip 6.0 standard conventional hybridization, and the corresponding scanning and computer software analysis results. (2) by PCR, FISH and SKY technology to further verify the microarray results, which identified the sensitivity and accuracy of diagnosis of unbalanced chromosome aberrations in Array-CGH technology. (3) C-banding and silver staining of two cases of suspected duplicate line of variation in heterochromatic regions further analysis and diagnosis, to help assess the condition and prognosis. (4) explore the array-CGH and FISH, SKY, G-banding, C-banding and other chromosome banding analysis techniques combined effects, the establishment of standard laboratory diagnostic process. 3, the follow-up on all cases of prenatal diagnosis routine follow-up. , 1.21 samples were successfully carried out the array-CGH Technical Analysis: G-band can not confirm the diagnosis of 17 cases of patients were at the DNA level clear the diagnosis, all cases were occurrence of large fragments of genomic DNA copy number variation. 4 normal control samples did not contain pathogenic DNA copy number variation. diagnosed as No. 13, the end of the long arm of chromosome 8.5MB of deletion: 46, XY, del (13) (q33.2 → q34). Cases 2,4,6 G-banding karyotype analysis found that a chromosome additional increase in the portion of the material, but can not determine the source of the substance, of which 4 cases and cases of father-daughter relationship. q22.3). Case 4 and Case 6 G-banding analysis of the proximal long arm of chromosome 9 more bands can not be confirmed. The aCGH analysis found that father and daughter chromosome 9 across repeats on both sides of the centromere DNA, 30 Mb size of the hereditary the aCGH result of 46, XX, dup (9) (9p13 → q13), Pat. 4 Case 3 and Case 5 genomic DNA were associated with duplication and lack of complexity of DNA copy number variation. Case 3 No. 8 short arm of chromosome number part of the material, but can not be confirmed [G-banding karyotype 46, XY, add (8)] of aCGH diagnosed with 8 short arm of chromosome DNA not only by the G-banding karyotype analysis repeat, concomitant missing: 46, XY, dup (8) (p21.3-p11.3), DE1 (8) (p23.3 → p23.1); case 5 G-banding karyotype analysis Mb deletion: 46, X, dup (X) (q21.31 → Q28), del (X) (p22.33 → p11.22). 5 7-10 cases were female patients, conventional G-banding karyotype analysis found no abnormalities, Array-CGH technology analysis found that 17 of these patients the middle of the long arm of chromosome occurred 380 kb microdeletion: 46, XX , del (17) (q21.31-q31.32). 6 Case 11-15 for female patients, conventional G-banding karyotype analysis found no abnormalities, line array-CGH technology analysis found that the end of the short arm of the X chromosome of the five cases containing 112 kb microdeletions: 46, XX , del (X) (p22.33). 7 cases 16-17 cases of prenatal diagnosis. Case 16 by G-banding karyotype analysis found no abnormalities, array-CGH analysis found that the fetal chromosome 22 proximal long arm of of 700 kb tiny missing: 46, XY, del (22) (q11.2), combined B-Tip fetal cardiac malformations, the diagnosis of DiGeorge syndrome The syndrome is often associated with mental retardation, pregnant women, termination of pregnancy; Case 17 from the maternal genetic balanced translocation, array-CGH analysis found no large fragment of pathogenic DNA copy number variation, taking into account the fetal phenotype and normal phenotype similar to pregnant women, it is recommended to continue the pregnancy; pregnant women term delivery of a baby boy, postpartum follow-up of the baby boy no any abnormal growth and development. All aCGH technology test results were confirmed by PCR and FISH technology validation, and verify the results of the aCGH results coincide. A conclusion Array-CGH technology is a new modern molecular karyotype analysis technology is a major breakthrough in the field of genetics research, chromosomal disorder diagnosis is accurate up to the level of the gene. High resolution and accuracy to effectively overcome or compensate for the limitations of the existing chromosomal diagnostic techniques. Array-CGH technology to avoid the metaphase chromosomes, directly to the standard test sample of DNA microarray human genome wrapped oligonucleotide probe hybridization, you can quickly and accurately determine the amount of the sample genome-wide DNA copy number, and exact location on the chromosome, clearly demonstrated that the gene content of the section of DNA variation, FISH, SKY metaphase chromosomes to detect carrier technology can not match advantage. Array-CGH technology used in clinical unbalanced chromosomal disease diagnosis and prenatal diagnosis, can be quickly and accurately confirm the diagnosis at the molecular level, to provide a scientific basis for clinical genetic counseling doctor genotype - phenotype analysis of the relationship, conducive to an accurate assessment of prognosis and guidance pregnancy outcomes. Array-CGH technology prominent feature of the samples tested genomic DNA copy number variation (copy number variations, CNV), DNA copy number increase or decrease in chromosomal aberrations (such as balanced translocation or inversion balance) did not happen with a certain limitations, requires a combination of G-banding and FISH analysis. For the aCGH technology detection results obtained, it is necessary to genetics workers corresponding to the biometric information database Now, in order to accurately judge the CNV is pathogenic change or benign variant. Unbalanced chromosome aberrations in cases chromosome analysis operation process is: First, a preliminary analysis of the use of G-banding technique, followed by the line array-CGH detection to confirm the diagnosis. Balanced translocation of DNA copy number changes did not happen and balance in place, and then further verification by FISH or PCR-line. C-banding and silver staining technique helps to verify the CNV occurs in heterochromatic regions and with the tissue, to help assist in the diagnosis and assessment of prognosis.
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