• Journal of Genetic Medicine
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• v.17 no.2
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• pp.79-82
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• 2020

In epilepsy-aphasia spectrum (EAS) disorders, mutations in the glutamate receptor ionotropic N-methyl-D-aspartate type subunit 2A (GRIN2A) have become important for screening the disease. Research into the phenotypic variability of several types of neurologic impairment involving these mutations is in progress. However, the non-neurological problems related to these mutations are poorly understood. EAS disorders usually have epileptic, cognitive, or behavioral manifestations. In this case report, we present a female patient with epilepsy, delay in expressive language and social development, and intellectual disability with low intelligence quotient and memory quotient, but normal motor development. Through genetic analysis, she was found to have a missense and a nonsense mutation in GRIN2A (c.1770A>C; p.Lys509Asn and c.3187G>T; p.Glu1063∗, respectively) and we consider the nonsense mutation as 'pathogenic variant'. She was also discovered to have congenital hypothyroidism, growth hormone deficiency and Rathke's cleft cyst in the brain, which were previously unknown features of GRIN2A mutation. Our findings should widen understanding of the spectrum of GRIN2A phenotypes, and emphasize the need for more research into the association between GRIN2A mutations and non-neurologic clinical presentations.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.4 no.1
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• pp.5-12
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• 2004

Purpose Phenylketonuria is an inborn error of metabolism, which is inherited as an autosomal recessive trait. PKU is resulting from deficiency of phenylalanine hydroxylase. PAH gene spans about 90 kb on chromosome 12q and comprises 13 exons. In order to define the genetic basis of PKU and the frequencies and distribution of PAH mutations in the Korean population, we analyzed PAH gene in independent 80 patients with PKU. Methods All 13 exons including exon-intron boundaries and 2 kb of 5' upstream region of the PAH gene were analyzed by PCR-direct sequencing methods. Results PAH gene analysis revealed 39 different mutations including 10 novel mutations. The novel mutations consisted of 9 missense mutations (P69S, G103S, N207D, T278S, P281A, L293M, G332V, S391I and A447P) and a novel splice site variant (IVS10-3C>G). R243Q, IVS4-1G>A, and E6-96A>G were the most relevant mutations and they accounted in the whole for 38% of the mutant alleles identified in this study. We also observed that. $BH_4$ responsibility was. associated with genotype of R241C, R53H and R408Q. Conc1ustion Our present study with 80 participants extends the previous results to more comprehensive understanding of PAH allele distribution and frequency in Koreans. Although Korean mutation profile of PAH is similar to those of the nearest oriental populations (Japanese, Chinese, and Taiwanese), several different characteristic features are revealed. The characterization of the genotype-phenotype relationship was also performed. Our data would be very useful information for diagnosis, genetic counseling and planning of dietary and therapeutic strategies in Korean PAH patients.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.3
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• pp.157-162
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• 2003

Our earlier studies found a significant correlation between the activities of ranitidine N-oxidation catalyzed by hepatic flavin-containing monooxygenase (FMO) and the presence of mutations in exon 4 (E158K) and exon 7 (E308G) of the FMO3 gene in Korean volunteers. However, caffeine N-1 demethylation (which is also partially catalyzed by FMO) was not significantly correlated with these FMO3 mutations. In this study, we examined another common mutation (V257M) in exon 6 of FMO3 gene. The V257M variant, which is caused by a point mutation (G769A), was commonly observed (13.21% allele frequency) in our subjects (n=159). This point mutation causes a substitution of $Val^{257}$ to $Met^{257}$, with transformation of the secondary structure. The presence of this mutant allele correlated significantly with a reduction in caffeine N-1-demethylating activity, but was not correlated with the activity of N-oxidation of ranitidine. In a family study, the low FMO activity observed in a person heterozygous for a nonsense mutation in exon 4 (G148X) and heterozygous for missense mutation in exon 6 (V257M) of FMO3 was attributed to the mutations. Our results suggest that various point mutations in the coding regions of FMO3 may influence FMO3 activity according to the probe substrates of varying chemical structure that correlate with each mutation on the FMO3 gene.

• Molecules and Cells
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• v.41 no.8
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• pp.733-741
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• 2018

Mutations in spliceosome components have been implicated in carcinogenesis of various types of cancer. One of the most frequently found is U2AF1 S34F missense mutation. Functional analyses of this mutation have been largely limited to hematological malignancies although the mutation is also frequently seen in other cancer types including lung adenocarcinoma (LUAD). We examined the impact of knockdown (KD) of wild type (wt) U2AF1 and ectopic expression of two splice variant S34F mutant proteins in terms of alternative splicing (AS) pattern and cell cycle progression in A549 lung cancer cells. We demonstrate that induction of distinct AS events and disruption of mitosis at distinct sub-stages result from KD and ectopic expression of the mutant proteins. Importantly, when compared with the splicing pattern seen in LUAD patients with U2AF1 S34F mutation, ectopic expression of S34F mutants but not KD was shown to result in common AS events in several genes involved in cell cycle progression. Our study thus points to an active role of U2AF1 S34F mutant protein in inducing cell cycle dysregulation and mitotic stress. In addition, alternatively spliced genes which we describe here may represent novel potential markers of lung cancer development.

• Genomics & Informatics
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• v.19 no.3
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• pp.29.1-29.10
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• 2021

In our previous studies, we have demonstrated the association of certain variants of the thyroid-stimulating hormone receptor (TSHR), thyroid peroxidase (TPO), and thyroglobulin (TG) genes with congenital hypothyroidism. Herein, we explored the mechanistic basis for this association using different in silico tools. The mRNA 3'-untranslated region (3'-UTR) plays key roles in gene expression at the post-transcriptional level. In TSHR variants (rs2268477, rs7144481, and rs17630128), the binding affinity of microRNAs (miRs) (hsa-miR-154-5p, hsa-miR-376a-2-5p, hsa-miR-3935, hsa-miR-4280, and hsa-miR-6858-3p) to the 3'-UTR is disrupted, affecting post-transcriptional gene regulation. TPO and TG are the two key proteins necessary for the biosynthesis of thyroid hormones in the presence of iodide and H₂O₂. Reduced stability of these proteins leads to aberrant biosynthesis of thyroid hormones. Compared to the wild-type TPO protein, the p.S398T variant was found to exhibit less stability and significant rearrangements of intra-atomic bonds affecting the stoichiometry and substrate binding (binding energies, ΔG of wild-type vs. mutant: -15 vs. -13.8 kcal/mol; and dissociation constant, K_d of wild-type vs. mutant: 7.2E^-12 vs. 7.0E^-11 M). The missense mutations p.G653D and p.R1999W on the TG protein showed altered ΔG(0.24 kcal/mol and 0.79 kcal/mol, respectively). In conclusion, an in silico analysis of TSHR genetic variants in the 3'-UTR showed that they alter the binding affinities of different miRs. The TPO protein structure and mutant protein complex (p.S398T) are less stable, with potentially deleterious effects. A structural and energy analysis showed that TG mutations (p.G653D and p.R1999W) reduce the stability of the TG protein and affect its structure-functional relationship.

• Journal of Yeungnam Medical Science
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• v.40 no.3
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• pp.283-288
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• 2023

Severe chronic neutropenia is classified as severe congenital, cyclic, autoimmune, or idiopathic. However, there is a lot of uncertainty regarding the diagnosis of severe congenital neutropenia (SCN) and chronic idiopathic neutropenia, and this uncertainty affects further evaluations and treatments. A 20-year-old man presented with fever and knee abrasions after a bicycle accident. On admission, his initial absolute neutrophil count (ANC) was 30/µL. He had no medical history of persistent severe neutropenia with periodic oscillation of ANC. Although his fever resolved after appropriate antibiotic therapy, ANC remained at 80/µL. Bone marrow (BM) aspiration and biopsy were performed, and a BM smear showed myeloid maturation arrest. Moreover, genetic mutation test results showed a heterozygous missense variant in exon 4 of the neutrophil elastase ELANE: c597+1G>C (pV190-F199del). The patient was diagnosed with SCN. After discharge, we routinely checked his ANC level and monitored any signs of infection with minimum use of granulocyte colony-stimulating factor (G-CSF), considering its potential risk of leukemic transformation. Considering that SCN can be fatal, timely diagnosis and appropriate management with G-CSF are essential. We report the case of a patient with SCN caused by ELANE mutation who had atypical clinical manifestations. For a more accurate diagnosis and treatment of severe chronic neutropenia, further studies are needed to elucidate the various clinical features of ELANE.

• Journal of Genetic Medicine
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• v.5 no.1
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• pp.26-33
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• 2008

Purpose : Phenylketonuria(PKU) is an inborn error of metabolism and a genetic disorder resulting from a deficiency of phenylalanine hydroxylase(PAH) and decreased activity of tetrahydrobiopterin(BH4).In this study the correlation between the DNA mutation and clinical manifestations was investigated and PAH DNA mutations were compared bewteen Asian and Caucasian populations. Methods : DNA was isolated from peripheral leukocytes. The PAH gene was amplified by Polymerase Chain Reaction(PCR) and the sequence was analyzed with Multiplex Ligation-dependent Probe Amplification(MLPA). Results : We characterized the PAH gene of 102 independent Korean patients with PKU. PAH nucleotide sequence analysis revealed 44 different mutations, including 10 novel mutations comprising 9 missense mutations(N207D, K95del, A447P, G344D, P69S, S391I, A202T, G103S, and I306L) and 1 novel splice-site variant mutation(IVS10-3C>G). R243Q was the most prevalent mutation in this study. A259T has not previously been reported in Asian populations, but we found that this mutation had a frequency of 10.1% in our study. Furthermore, the genotypes of $BH_4$ responsive patients were analyzed and were divided into two groups: $BH_4$ medication-only group and $BH_4$ medication with diet therapy group. In the $BH_4$ medication-only group and $BH_4$ medication with diet therapy group, R241C was the most common mutation. Conclusion : Novel mutations in the PAH gene of PKU patients are still being discovered. Additional information as to the frequency of mutations in the tetrahydrobiopterine responsive gene is also accumulating. We anticipate that knowledge of these PKU gene mutations will assist the diagnosis, genetic counseling, and therapeutic treatment of PKU patients in future.

• Journal of Life Science
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• v.31 no.10
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• pp.913-921
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• 2021

Limb-girdle muscular dystrophy (LGMD) which is characterized by progressive muscle weakening of the hip and shoulder shows both dominant and recessive inheritances with many pathogenic genes including TTN. This study performed to identify genetic causes of a male patient with late onset (45 years old) autosomal recessive LGMD and atrial flutter. By application of the whole exome sequencing, we identified bi-allelic variants of TTN gene in the patient. One allele had a single missense variant of [c.24124G>T (p.V8042F)], while the other allele consisted of three missense variants of [c.29222G>C (p.R9741P) + c.67490A>G (p.H22497R) + c.75376C>T (p.R25126C)]. The p.V8042F allele was transmitted from his mother, while the other haplotype allele was putatively transmitted from his father. His two unaffected sons had only the p.R9741P. These variants have been not reported or rarely reported in the public human genome databases (1,000 Genome, gnomAD, and KRGDB). Most variants were located in the highly conserved immunoglobulin or fibronectin domains and were predicted to be pathogenic by the in silico analyses. The TTN giant protein plays a key role in muscle assembly, force transmission at the Z-line, and maintenance of resting tension in the I-band. In conclusion, we think that these bi-allelic compound heterozygous mutations may play a role as the genetic causes of the LGMD phenotype.

• Journal of Life Science
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• v.31 no.5
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• pp.453-463
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• 2021

Hearing loss is a group of clinically and genetically heterogeneous disorders characterized by congenital- to adult-onset deafness with frequent additional symptoms such as myopathy, nephropathy, and optic disorders. It is commonly divided into two types: syndromic, with no other symptoms, and nonsyndromic, with other symptoms. Autosomal recessive hearing loss is relatively frequent in Pakistan, which may be due in part to frequent consanguineous marriages. This study was performed by whole exome sequencing to determine the genetic causes in two Pakistani consanguineous families with autosomal recessive hearing loss. We identified a pathogenic homozygous variant (p.Leu326Gln in MYO7A) in a family with prelingual-onset hearing loss and two variants of uncertain significance (p.Val3094Ile in GPR98 and p.Asp56Gly in PLA2G6) in a family with early-onset hearing loss concurrent with muscular atrophy. The missense mutations in MYO7A and PLA2G6 were located in the highly conserved sites, and in silico analyses predicted pathogenicity, while the GPR98 mutation was located in the less conserved site, and most in silico analysis programs predicted its nonpathogenic effect. Homozygosity mapping showed that both alleles of the homozygous mutations identified in each family originated from a single founder; spread from this single source might be due to consanguineous marriages. This study will help provide exact molecular diagnosis and treatment for autosomal recessive hearing loss patients in Pakistan.

• Journal of Life Science
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• v.24 no.2
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• pp.181-185
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• 2014

We identified SNPs (single nucleotide polymorphisms) for endothelial nitric oxide synthase (eNOS) genes in the Korean genome. eNOS is present in the vascular endothelium, platelets, and several other cell types that continuously produce modest amounts of NO. Endothelium-derived NO plays a key role in the regulation of vascular tone, and the impaired effects of NO on the cardiovascular system appear to be responsible for coronary atherosclerosis and thrombosis. In recent studies, a missense variant within exon 7 of the eNOS gene in patients with coronary spastic angina-GAG to GAT substitution, which results in the replacement of glutamic acid by aspartic acid (Glu298Asp [G894T])-has been identified and is known to be significantly associated with coronary spasm. We prepared PCR primers based on sequences in Genbank. Primers were prepared for normal and SNPs separately, as reported for other Asian countries, such as G894T. Their sequences were different only at the 3' ends so that primer extension could only by possible when base pairs between templates and primers matched. We also employed ARMS (Amplification Refractory Mutation System) technology to improve the specificity of the PCR reaction. In conclusion, we were able to demonstrate the eNOS G894A polymorphism in Korean gemone. This study should facilitate research on the cause of myocardial infarction and development on further therapy at the genetic level.