• Journal of The Korean Society of Inherited Metabolic disease
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• v.5 no.1
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• pp.108-115
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• 2005

Inherited metabolic diseases (IMD) comprise a large class of genetic diseases involving disorders of metabolism. The majorities are due to defects of single genes that code for enzymes that facilitate conversion of various substances into others. Because of the multiplicity of conditions, many different diagnostic tests are used for screening of IMD. Molecular genetic diagnosis is the detection of pathogenic mutations in DNA and/or RNA samples and is becoming a much more common practice in medicine today. The purpose of molecular genetic testing in IMD includes diagnostic testing, pre-symptomatic testing, carrier screening, prenatal diagnosis, preimplantation testing, and population screening. However, because of the complexity, difficulty in interpreting the result, and the ethical considerations, an understanding of technical, conceptual, and practical aspects of molecular genetic diagnosis is mandatory.

• Journal of Genetic Medicine
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• v.5 no.1
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• pp.1-6
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• 2008

Knowledge of developmental biology is essential for clinicians who seek to develop a rational approach to the diagnostic evaluation of patients with birth defects. After an accurate diagnosis, a clinician can make predictions about prognosis, recommend management options, and provide an indication of recurrence risk for the parents and relatives. In this paper, we first review the basic mechanisms of embryological development and clinical dysmorphology. We then review cellular and molecular mechanisms in development and related congenital anomalies. Developmental anomalies have a major impact on public health. Genetic counseling and prenatal diagnosis, with the option to continue or to terminate a pregnancy, are important for helping families faced with the risk of a serious congenital anomaly in their offspring. Moreover, primary prevention of birth defects, for example, supplementation of prenatal folic acid and prevention of consumption of alcohol which has teratogenic effects, can be accomplished using developmental biology knowledge.

• Development and Reproduction
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• v.22 no.2
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• pp.199-203
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• 2018

Although trisomy 16 is commonly detected in spontaneous abortions and accounts for over 30% of cases of autosomal trisomy detected after spontaneous abortion, trisomy 16 mosaicism is rarely detected by amniocentesis in the second trimester. Here, we report a case of level III trisomy 16 mosaicism (47,XX,+16[8]/46,XX[31]) diagnosed by cytogenetic analysis of independently cultured amniotic fluid cells. The female baby was delivered at full term with low birth weight and intrauterine growth retardation, and interestingly, her karyotype was normal (46,XX). Given the difficulty in predicting the outcomes of fetuses with this mosaicism, it is recommended to inform the possibility of mosaicisms including this trisomy 16 mosaicism during prenatal genetic diagnosis and genetic counseling for parents.

• Journal of Genetic Medicine
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• v.12 no.2
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• pp.72-78
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• 2015

Recently, noninvasive prenatal test (NIPT) has been adopted as a primary screening tool for fetal chromosomal aneuploidy. The principle of NIPT lies in isolating the fetal fraction of cell-free DNA in maternal plasma and analyzing it with bioinformatic tools to measure the amount of gene from the target chromosome, such as chromosomes 21, 18, and 13. NIPT will contribute to decreasing the need for unnecessary invasive procedures, including amniocentesis and chorionic villi sampling, for confirming fetal aneuploidy because of its higher positive predictive value than that of the conventional prenatal screening method. However, its greater cost than that of the current antenatal screening protocol may be an obstacle to the adoption of this innovative technique in clinical practice. Digital polymerase chain reaction (dPCR) is a novel approach for detecting and quantifying nucleic acid. dPCR provides real-time diagnostic advantages with higher sensitivity, accuracy, and absolute quantification than conventional quantitative PCR. Since the groundbreaking discovery that fetal cell-free nucleic acid exists in maternal plasma was reported, dPCR has been used for the quantification of fetal DNA and for screening for fetal aneuploidy. It has been suggested that dPCR will decrease the cost by targeting specific sequences in the target chromosome, and dPCR-based noninvasive testing will facilitate progress toward the implementation of a noninvasive approach for screening for trisomy 21, 18, and 13. In this review, we highlight the principle of dPCR and discuss its future implications in clinical practice.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.5 no.1
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• pp.94-107
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• 2005

Prenatal diagnosis (PND) such as amniocentesis or chorionic villi sampling has been widely used in order to prevent the birth of babies with defects especially in families with single gene disorderor chromosomal abnormalities. Preimplantation genetic diagnosis (PGD) has already become an alternative to traditional PND. Indications for PGD have expanded beyond those practices in PND (chromosomal abnormalities, single gene defects), such as late-onset diseases with genetic predisposition, and HLA typing for stem cell transplantation to affected sibling. After in vitro fertilization, the biopsied blastomere from the embryo is analyzed for single gene defect or chromosomal abnormality. The unaffected embryos are selected for transfer to the uterine cavity. Therefore, PGD has an advantage over PND as it can avoid the risk of pregnancy termination. In this review, PGD will be introduced and application of PGD in inborn error metabolic disorder will be discussed.

• Journal of Genetic Medicine
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• v.2 no.2
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• pp.49-51
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• 1998

Wolf-Hirschhorn syndrome (WHS) is caused by a deletion of the short arm on chromosome 4 and is characterized by multiple congenital abnormalities, growth and mental retardation. In this case report, we performed amniocentesis for the chromosome analysis on a 25-year-old pregnant woman at 16 weeks of gestation whom we suspected of Edward's syndrome by the triple test of maternal serum and ultrasonography. The result of analysis revealed a karyotype of the fetus with 46,XY,del(4)(p15) by trypsin Giemsa's banding technique. With the result, we were able to diagnose the fetus as having WHS. As such, after therapeutic termination of the pregnancy, we confirmed WHS through the sampling of tissue by both trypsin Giemsa's banding and fluorescence in situ hybridization (FISH) method. To determine the origin of the WHS, we further tested the karyotypes of the parents. As parental karyotypes were found to be normal, we determined the case of the fetal WHS to be de novo.

• Journal of Genetic Medicine
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• v.12 no.2
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• pp.66-71
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• 2015

Down syndrome screening with cell-free DNA (cfDNA) in the maternal plasma has recently received much attention in the prenatal diagnostic field. Indeed, a large amount of evidence has already accumulated to show that screening tests with cfDNA are more sensitive and specific than conventional maternal serum and/or ultrasound screening. Globally, more than 1,000,000 of these noninvasive prenatal tests (NIPTs) have been performed to date. There are several different methods for NIPTs that are currently commercially available, including shotgun massively parallel sequencing, targeted massively parallel sequencing, and single nucleotide polymorphism (SNP)-based methods. All of these methods have their own advantages and disadvantages. In this review, I will focus specifically on the SNP-based NIPT.

• Journal of Interdisciplinary Genomics
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• v.5 no.2
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• pp.24-28
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• 2023

Chromosomal microarray (CMA) is primarily recommended for detecting clinically significant copy number variants (CNVs) in the genetic diagnosis of developmental delay, intellectual disability, autism, and congenital malformations. Prenatal CMA is recommended when a fetus has major congenital malformations. The main principles of CMA can be divided into array comparative genomic hybridization and single-nucleotide polymorphism arrays. In the current CMA platforms, these two principles are combined, and detection of genetic abnormalities including CNVs and absence of heterozygosity is facilitated. In this review, I described practical assessment of CMA testing regarding to laboratory management of CMA, interpretation of CNVs, and special considerations for comprehensive genetic counseling.

• Clinical and Experimental Reproductive Medicine
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• v.24 no.1
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• pp.51-56
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• 1997

Recently, through the development of the primer extension preamplification(PEP) method which amplifies the whole genome, simultaneous multiple DNA analysis has become possible. Whole genome from each single cell can be amplified using 15 base oligonucleotide random primer. The greatest advantage of PEP-PCR is the ability to investigate several loci simultaneously and confirm results by analysing multiple aliquots for each locus. This technique led to the development of preimplantation genetic disease diagnosis using blastomere from early embryo, sperm, polar body and oocyte. In this study, we applied PEP-PCR in 20 cases of single amniocyte and 20 cases of single chorionic villus cell for the clinical application of the prenatal and preimplantational genetic diagnosis. We analysed 7 gene loci simultaneously which are 46, 47 exons related to dystrophin gene, two VNTR (variable number tandem repeat) markers using 5'dysIII, 3'CA related to dystrophin gene and DYZ1, DYZ3, DYS14 regions on chromosome Y. In all the tests, 97.5% of PEP-PCR amplifications with single cells were successful. We obtained 38/40 (95%) accuracy in gender determination through chromosome analysis comparison. Therefore, these results have significant implications for a sperm or oocyte analysis and prenatal or preimplantational genetic diagnosis.

• Journal of mucopolysaccharidosis and rare diseases
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• v.2 no.1
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• pp.19-22
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• 2016

Purpose: Mucolipidosis type II (ML II), also known as I-cell disease is an autosomal recessive inherited disorder of lysosomal enzyme transport caused by a deficiency of the uridine diphosphate (UDP)-N-acetylglucosamine:lysosomal enzyme N-acetylglucosamine-1-phosphotransferase (GlcNAc-phosphotransferase). Clinical manifestations are skeletal abnormalities, mental retardation, cardiac disease, and respiratory complications. A severely and rapidity progressive clinical course leads to death before 10 years of age. Methods/Results: In this study we diagnosed three cases of prenatal ML II in two different at-risk families. We compared two procedures -biochemical analysis and molecular analysis - for the prenatal diagnosis of ML II. Both methods require an invasive procedure to obtain specimens for the diagnosis. Biochemical analysis requires obtaining cell cultures from amniotic fluid for more than two weeks, and would result in a late diagnosis at 19 to 22 weeks of gestation. Molecular genetic testing by direct sequence analysis is usually possible when mutations are confirmed in the proband. Molecular analysis has an advantage in that it can be performed during the first-trimester. Conclusion: Molecular diagnosis is a preferable method when a prompt decision is necessary.