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권경훈 ( Kyoung Hun Kwon ),정해원 ( Hai Won Chung ) 서울대학교 인구의학연구소 2013 人口醫學硏究論集 Vol.26 No.-
New advances in the use of cell free fetal DNA in maternal plasma of pregnant women has provided the possibility of applying cell free fetal DNA in prenatal diagnosis as non-invasive method, Cell free fetal DNA can be detected as early as 4 weeks` gestation and exceeds 4% of all the cell free DNA in nearly all women from 10 weeks onward. Therefore, cell free fetal DNA has been proposed as a potential material for non-invasive prenatal genetic diagnosis. Recently, analysis of cell free fetal DNA in maternal blood for non-invasive prenatal testing has been shown to be highly accurate in the detection of common fetal autosomal trisomies. In this review, we discuss the most recent advances in methods for non-invasive prenatal diagnosis and their implications in clinical application.
권경훈 ( Kyoung Hun Kwon ),정해원 ( Hai Won Chung ) 서울대학교 인구의학연구소 2014 人口醫學硏究論集 Vol.27 No.-
Impressive progress has been made in the field of next generation sequencing (NGS). The NGS technologies are able to produce millions of shot sequence reads in a high-throughput, cost-effective fashion. Advance in the field of sequencing techniques has resulted in the grearly accelerated production of huge sequence datasets. NGS technologies from Illumina/Solexa, ABI/SOLiD, 454/Roche, and Helicos, have provided unprecedented opportunities for high-throughput functional genomic research. NGS-based genomic data have been exploited to better understand disease development and patient characteristics that influence response to a given therapeutic intervention. In this article, we introduce principle of NGS technique and genetic diagnostic application of NGS.
권경훈 ( Kyoung Hun Kwon ),정해원 ( Hai Won Chung ) 서울대학교 인구의학연구소 2012 人口醫學硏究論集 Vol.25 No.-
The next generation sequencing (NGS) is faster and a lower cost new sequencing technique getting huge-large scale fragment, called reads, and sequence data than traditional sequencing. NGS technologies include a number of methods that are grouped broadly as template preparation, sequencing and imaging, and data analysis. Recently available next generation sequencer are the GS-FLX (Roche). Genome Analyzer (Illumina), and SOLiD (Life Technologies). However, the NGS produces much shorter sequences and large volumes of reads compared to conventional sequencing, whereby huge amounts of short reads are aligned onto a reference. For fast mapping of the massive amounts of short reads, a lot of mapping algorithms and programs have been developed. In this article, we introduce NGS technique and application of NGS.
권경훈 ( Kyoung Hun Kwon ),정해원 ( Hai Won Chung ) 서울대학교 인구의학연구소 2011 人口醫學硏究論集 Vol.24 No.-
The frequency of feral malformations accounts for around 3~5%, and evaluation for the health of the fetus and screening for fetal malformations have become an important part of prenatal cares. Fetal malformations can be classified into structural and chromosomal abnormalities. Improvements in prenatal diagnosis have allowed identification of malformations in fetuses during the first and second trimesters of pregnancy. In prenatal diagnosis, both screening and diagnostic procedures are included. Screening rests include maternal serum aneuploidy screening tests, which are triple marker tests and quadruple test. Recently, first trimester combined ultrasound-biochemical screening and integrated screening was introduced and provided higher detection rates of chromosomal anomalies. Diagnostic tests are usually performed when screening results are positive, and they include chorionic villi sampling, amniocentesis, cordocentesis and fetal cells in maternal blood and preimplantation genetic diagnosis (PGD). In this review, we describe prenatal screening test, genetic diagnosis and its clinical significance.
권경훈 ( Kyoung Hun Kwon ),정해원 ( Hai Won Chung ) 서울대학교 인구의학연구소 2010 人口醫學硏究論集 Vol.23 No.-
Mosaicism is the presence of two or more chromosomally distinct cell lines, each seen in two or more cells. It arises after fertilization through inaccurate segregation of chromosomes at mitosis. Two mechanisms have been postulated to account for errors of segregation. Nondisjunction is the failure of the two chromatids to separate at the centromere at metaphase, causing both chromatids to go to the same daughter cell and leading to one hyperdiploid cell and one hypodiploid cell. Chromosome mosaicism is found in about 1% of amniotic fluid cell cultures. Mosaicism detected in amniotic fluid may represent the true mosaicism or may pseudomosaicism. If the same chromusome abnormality is seen in more than one cell and in two different cultures, it is considered a true mosaicism, whereas single-cell abnormalities from a single culture are regarded as pseudomosaicism. In this review, we describe a mosaicism in chromosome analysis, its diagnostic problems and clinical significance.
황시목 ( Si Mok Hwang ),권경훈 ( Kyoung Hun Kwon ) 서울대학교 인구의학연구소 2013 人口醫學硏究論集 Vol.26 No.-
The prognosis of malformation is dictated mainly by proper treatment followed by correct diagnosis at an early age. Congenital malformations are single or multiple defects of the morphogenesis of organs or body districts identifiable at birth or during the intrauterine life. Both genetic and environmental factors, as well as their combination in a multifactorial contest, may induce defects. In practice, etiological consideration and classification of anomalies are critical for diagnosis. Congenital malformation is observed in about 2-3% of newborns and is a leading cause of infant mortality. Fetal malformations can be classified into structural and chromosomal abnormalities. Improvements in prenatal diagnosis have allowed identification of malformations in fetuses during the first and second trimesters of pregnancy. In prenatal diagnosis, both screening and diagnostic procedures are included. Genetic counseling aids this process by helping patients of family members understand and the nature of the malformation and risk assessment.
황시목 ( Si Mok Hwang ),권경훈 ( Kyoung Hun Kwon ),오선경 ( Sun Kyung Oh ) 서울대학교 인구의학연구소 2012 人口醫學硏究論集 Vol.25 No.-
This study was performed to analyze the indications and to evaluate the recent ftequency of karyotypes in different sex chromosome abnormalities. We investigated 26 cases(amniotic fluid 8 cases, peripheral blood 12 cases, abortus tissue 5 cases, chorionic villus sampling 1 case) in which sex chromosome abnormalities has been found in cytogenetic analysis. The frequencies of different sex chromosome abnormalities were Turner syndrome 61.6%(16/26), Klinefelter syndrome 30.8%(8/26), XYY syndrome 3.8% and XX male 3.8%. We have to pay careful attention in diagnoses of Turner syndrome because of the high proportion of mosaicism. In this study, we will be provided information in sex chromosome abnormalities analysis, its diagnostic problems and make possible genetic counseling.
황시목 ( Si Mok Hwang ),권경훈 ( Kyoung Hun Kwon ) 서울대학교 인구의학연구소 2015 人口醫學硏究論集 Vol.28 No.-
Chromosome disorders are a major category of genetic disease. The chromosomal anomalies typically arise from alterations in the DNA containing chromosomal regions and can be reliably detected by karyotype analysis. They account for a large proportion of all reproductive wastage, congenital malformation, and mental retardation and play an important role in the pathogenesis of malignancy. Specific chromosome abnormalities are responsible for more than 100 identifiable syndromes that are collectively more common than all the mendelian single-gene disorders together. Cytogenetic disorders are present in nearly 1 percent of live births, in abour 2 percents of pregnancies in women older than 35 years who undergo prenatal diagnosis, and in fully half of all spontaneous first-trimester abortions. Abnormalities of chromosomes may be either numerical or structural and may involve on or more aurosomes, sex chromosomes, or both simultaneously. The clinical and social impact of chromosome abnormalities is enormous.