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89 result(s) for "Cheong, Hyun Sub"
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Exploring the Novel Susceptibility Gene Variants for Primary Open-Angle Glaucoma in East Asian Cohorts: The GLAU-GENDISK Study
Primary open-angle glaucoma (POAG) can develop even within normal ranges of intraocular pressure, and this type of glaucoma (so-called ‘normal-tension glaucoma [NTG]’) is highly prevalent in East Asia including Korea and Japan. We conducted exome chip analysis to identify low-frequency and rare variants associated with POAG from the primary cohort (309 POAG patients and 5,400 control, all Koreans). For replication, Korean (310 POAG patients and 5,612 controls) and Japanese (565 POAG patients and 1,104 controls) cohorts were further investigated by targeted genotyping. SNP rs116121322 in LRRC27 showed nominally significant association with POAG in the discovery cohort (OR = 29.85, P  = 2E–06). This SNP was validated in the Korean replication cohort but only in the NTG subgroups (OR = 9.86, P  = 0.007). Japanese replication cohort did not show significant association with POAG ( P  .00.44). However, the meta-analysis in the entire cohort revealed significant association of rs116121322 with POAG (OR combined  = 10.28, P combined  = 1.4E–07). The LRRC27 protein expression was confirmed from human trabecular meshwork cells. For gene-based testing, METTL20 showed a significant association in POAG ( P combined  = 0.002) and in the subgroup of NTG ( P combined  = 0.02), whereas ZNF677 were significantly associated with only in the subgroup of high-tension glaucoma ( P combined  = 1.5E–06). Our findings may provide further genetic backgrounds into the pathogenesis of POAG, especially for the patients who have lower baseline intraocular pressures.
The schizophrenia genetics knowledgebase: a comprehensive update of findings from candidate gene studies
Over 3000 candidate gene association studies have been performed to elucidate the genetic underpinnings of schizophrenia. However, a comprehensive evaluation of these studies’ findings has not been undertaken since the decommissioning of the schizophrenia gene (SzGene) database in 2011. As such, we systematically identified and carried out random-effects meta-analyses for all polymorphisms with four or more independent studies in schizophrenia along with a series of expanded meta-analyses incorporating published and unpublished genome-wide association (GWA) study data. Based on 550 meta-analyses, 11 SNPs in eight linkage disequilibrium (LD) independent loci showed Bonferroni-significant associations with schizophrenia. Expanded meta-analyses identified an additional 10 SNPs, for a total of 21 Bonferroni-significant SNPs in 14 LD-independent loci. Three of these loci (MTHFR, DAOA, ARVCF) had never been implicated by a schizophrenia GWA study. In sum, the present study has provided a comprehensive summary of the current schizophrenia genetics knowledgebase and has made available all the collected data as a resource for the research community.
Cytidine deaminase polymorphisms and worse treatment response in normal karyotype AML
The cytidine deaminase (CDA) catalyzes the irreversible hydrolytic deamination of the cytarabine (AraC) into a 1-β-D-arabinofuranosyluracil (AraU), an inactive metabolite that plays a crucial role in lowering the amount of AraC, a key chemotherapeutic drug, in the treatment of patients with acute myeloid leukemia (AML). In this study, we hypothesized that CDA polymorphisms were associated with the AraC metabolism for AML treatment and/or related clinical phenotypes. We analyzed 16 polymorphisms of CDA among 50 normal karyotype AML (NK-AML) patients, 45 abnormal karyotype AML (AK-AML) patients and 241 normal controls (NC). Several polymorphisms and haplotypes, rs532545, rs2072671, rs471760, rs4655226, rs818194 and CDA-ht3, were found to have a strong correlation with NK-AML compared with NC and these polymorphisms also revealed strong linkage disequilibrium with each other. Among them, rs2072671 (79A>C), which is located in a coding region and the resultant amino acid change K27Q, showed significant associations with NK-AML compared with NC (P=0.009 and odds ratio=2.44 in the dominant model). The AC and CC genotypes of rs2072671 (79A>C) were significantly correlated with shorter overall survival rates (P=0.03, hazard ratio=1.84) and first complete remission duration (P=0.007, hazard ratio=3.24) compared with the AA genotype in the NK-AML patients. Our results indicate that rs2072671 in CDA may be an important prognostic marker in NK-AML patients.
A novel variant of telomerase reverse transcriptase (TERT) associated with risk of glioma in a Korean population
Among central nervous system (CNS) tumors, gliomas are the most prevalent type of tumor. Single nucleotide polymorphisms (SNPs) in telomerase reverse transcriptase ( TERT ) gene have been identified as risk loci for gliomas by previous genome-wide association studies (GWAS). We examined association between TERT variants and glioma risk in a Korean population. For a case-control study, a total of 32 TERT SNPs from 317 patients with glioma and 480 population-based controls were genotyped. Logistic regression was used for statistical analysis of the link between TERT SNPs and risk of glioma. In this study, eight TERT variants, including four glioma-associated variants reported in previous studies, showed significant association with the risk of glioma. Conditional and stepwise analyses were conducted to validate independent associations in the group of the eight variants. Both analyses identified an intronic variant ( rs56345976 ) as the causal variant among the eight variants. Glioma subgroup analyses indicate that rs56345976 variant is associated with the risk of WHO grade 4, glioblastoma, isocitrate dehydrogenase (IDH) wild-type, and 1p/19q non-codeletion glioma. This study presents a profound comprehension of the relationship between TERT variants and the risk of glioma. Further studies of this variant are required to investigate its effect on glioma susceptibility.
Two independent variants of epidermal growth factor receptor associated with risk of glioma in a Korean population
Gliomas are the most common primary tumors in the brain and spinal cord. In previous GWASs, SNPs in epidermal growth factor receptor ( EGFR ) have been reported as risk loci for gliomas. However, EGFR variants associated with gliomas in the Korean population remain unstudied. This study explored the association of EGFR SNPs with the risk of glioma. We genotyped 13 EGFR exon SNPs in a case–control study that included 324 Korean patients diagnosed with glioma and 480 population-based controls. Statistical analyses of the association between EGFR SNPs and glioma risk were conducted using logistic regression. Both stepwise analysis and conditional logistic analysis were performed to identify independent associations among genotyped variants. We confirmed that two SNPs ( rs2227983, rs1050171 ) were significantly associated with glioma ( rs2227983 : odds ratio = 1.42, P corr  = 0.009; rs1050171 : odds ratio = 1.68, P corr  = 0.005). Additionally, the stepwise analysis and conditional logistic analysis indicated that both SNPs created variants with independent genetic effects. This study is the first to show evidence that functional variants of EGFR , namely, rs2227983 (K521R) and rs1050171 (Q787Q), are associated with an increased risk of glioma in the Korean population. Future work should confirm the functional association between EGFR variants and glioma.
TPX2 prompts mitotic survival via the induction of BCL2L1 through YAP1 protein stabilization in human embryonic stem cells
Genetic alterations have been reported for decades in most human embryonic stem cells (hESCs). Survival advantage, a typical trait acquired during long-term in vitro culture, results from the induction of BCL2L1 upon frequent copy number variation (CNV) at locus 20q11.21 and is one of the strongest candidates associated with genetic alterations that occur via escape from mitotic stress. However, the underlying mechanisms for BCL2L1 induction remain unknown. Furthermore, abnormal mitosis and the survival advantage that frequently occur in late passage are associated with the expression of BCL2L1 , which is in locus 20q11.21. In this study, we demonstrated that the expression of TPX2 , a gene located in 20q11.21, led to BCL2L1 induction and consequent survival traits under mitotic stress in isogenic pairs of hESCs and human induced pluripotent stem cells (iPSCs) with normal and 20q11.21 CNVs. High Aurora A kinase activity by TPX2 stabilized the YAP1 protein to induce YAP1-dependent BCL2L1 expression. A chemical inhibitor of Aurora A kinase and knockdown of YAP/TAZ significantly abrogated the high tolerance to mitotic stress through BCL2L1 suppression. These results suggest that the collective expression of TPX2 and BCL2L1 from CNV at loci 20q11.21 and a consequent increase in YAP1 signaling promote genome instability during long-term in vitro hESC culture. Stem cells: Maintaining stable cell cultures New details of the molecular mechanisms behind problematic genetic aberrations that can affect cultured human embryonic stem cells could help efforts to maintain stable cell lines that hold great promise for treating a wide variety of diseases. Researchers in South Korea led by Hyuk-Jin Cha at Seoul National University investigated abnormalities in stem cell control systems leading to a condition known as survival advantage, which can allow abnormal cells to proliferate. They identified a gene ( TPX2 ) whose expression activates another gene already known to be involved in triggering the survival advantage process. Their research further revealed that the protein encoded by TPX2 achieves this effect indirectly, by interacting with another protein known to be able to control the activity of specific genes. Revealing this molecular signaling chain could assist culture of stable stem cells.
A Genome-Wide Association Study Identifies Potential Susceptibility Loci for Hirschsprung Disease
Hirschsprung disease (HSCR) is a congenital and heterogeneous disorder characterized by the absence of intramural nervous plexuses along variable lengths of the hindgut. Although RET is a well-established risk factor, a recent genome-wide association study (GWAS) of HSCR has identified NRG1 as an additional susceptibility locus. To discover additional risk loci, we performed a GWAS of 123 sporadic HSCR patients and 432 unaffected controls using a large-scale platform with coverage of over 1 million polymorphic markers. The result was that our study replicated the findings of RET-CSGALNACT2-RASGEF1A genomic region (rawP = 5.69×10(-19) before a Bonferroni correction; corrP = 4.31×10(-13) after a Bonferroni correction) and NRG1 as susceptibility loci. In addition, this study identified SLC6A20 (adjP = 2.71×10(-6)), RORA (adjP = 1.26×10(-5)), and ABCC9 (adjP = 1.86×10(-5)) as new potential susceptibility loci under adjusting the already known loci on the RET-CSGALNACT2-RASGEF1A and NRG1 regions, although none of the SNPs in these genes passed the Bonferroni correction. In further subgroup analysis, the RET-CSGALNACT2-RASGEF1A genomic region was observed to have different significance levels among subgroups: short-segment (S-HSCR, corrP = 1.71×10(-5)), long-segment (L-HSCR, corrP = 6.66×10(-4)), and total colonic aganglionosis (TCA, corrP>0.05). This differential pattern in the significance level suggests that other genomic loci or mechanisms may affect the length of aganglionosis in HSCR subgroups during enteric nervous system (ENS) development. Although functional evaluations are needed, our findings might facilitate improved understanding of the mechanisms of HSCR pathogenesis.
Association analysis of RTEL1 variants with risk of adult gliomas in a Korean population
Previous studies have identified multiple loci for inherited susceptibility to glioma development, including the regulator of telomere elongation helicase 1 (RTEL1). However, the association between RTEL1 variants and risk of glioma has not been well understood. Therefore, we sought to comprehensively examine the genetic interaction between RTEL1 variants and risk of glioma with respect to defined histological and molecular subtypes. We employed a case-control study involving 250 adult glioma patients with previous molecular alterations and 375 population-based controls within Korean populations. Statistical analyses on the association between RTEL1 single nucleotide polymorphisms (SNPs) and glioma risk were conducted using unconditional logistic regression. Additional conditional and stepwise analyses were performed on significant RTEL1 SNPs. We detected significant associations (Bonferroni P < .05) between six SNPs (rs6089953, rs3848669, rs6010620, rs3787089, rs6062302, and rs115303435) and risk of glioma in the Korean subjects. The two coding variants, rs6062302 (D664D) and rs115303435 (A1059T), were plausibly causal variants and were independent among the significantly associated RTEL1 variants. The glioma subgroup analyses showed that the causal variants (rs6062302 and rs115303435) may be associated with increased risk of glioma regardless of histological grades and molecular alterations. This study provides a deeper understanding of relationships between RTEL1 variants and risk of glioma. Further studies are required to ascertain the impact of those variants on glioma susceptibility.
Identification of copy number variations and common deletion polymorphisms in cattle
Background Recently, the discovery of copy number variation (CNV) led researchers to think that there are more variations of genomic DNA than initially believed. Moreover, a certain CNV region has been found to be associated with the onset of diseases. Therefore, CNV is now known as an important genomic variation in biological mechanisms. However, most CNV studies have only involved the human genome. The study of CNV involving other animals, including cattle, is severely lacking. Results In our study of cattle, we used Illumina BovineSNP50 BeadChip (54,001 markers) to obtain each marker's signal intensity (Log R ratio) and allelic intensity (B allele frequency), which led to our discovery of 855 bovine CNVs from 265 cows. For these animals, the average number of CNVs was 3.2, average size was 149.8 kb, and median size was 171.5 kb. Taking into consideration some overlapping regions among the identified bovine CNVs, 368 unique CNV regions were detected. Among them, there were 76 common CNVRs with > 1% CNV frequency. Together, these CNVRs contained 538 genes. Heritability errors of 156 bovine pedigrees and comparative pairwise analyses were analyzed to detect 448 common deletion polymorphisms. Identified variations in this study were successfully validated using visual examination of the genoplot image, Mendelian inconsistency, another CNV identification program, and quantitative PCR. Conclusions In this study, we describe a map of bovine CNVs and provide important resources for future bovine genome research. This result will contribute to animal breeding and protection from diseases with the aid of genomic information.
Frequent Amplification of CENPF, GMNN and CDK13 Genes in Hepatocellular Carcinomas
Genomic changes frequently occur in cancer cells during tumorigenesis from normal cells. Using the Illumina Human NS-12 single-nucleotide polymorphism (SNP) chip to screen for gene copy number changes in primary hepatocellular carcinomas (HCCs), we initially detected amplification of 35 genes from four genomic regions (1q21-41, 6p21.2-24.1, 7p13 and 8q13-23). By integrated screening of these genes for both DNA copy number and gene expression in HCC and colorectal cancer, we selected CENPF (centromere protein F/mitosin), GMNN (geminin, DNA replication inhibitor), CDK13 (cyclin-dependent kinase 13), and FAM82B (family with sequence similarity 82, member B) as common cancer genes. Each gene exhibited an amplification frequency of ~30% (range, 20-50%) in primary HCC (n = 57) and colorectal cancer (n = 12), as well as in a panel of human cancer cell lines (n = 70). Clonogenic and invasion assays of NIH3T3 cells transfected with each of the four amplified genes showed that CENPF, GMNN, and CDK13 were highly oncogenic whereas FAM82B was not. Interestingly, the oncogenic activity of these genes (excluding FAM82B) was highly correlated with gene-copy numbers in tumor samples (correlation coefficient, r>0.423), indicating that amplifications of CENPF, GMNN, and CDK13 genes are tightly linked and coincident in tumors. Furthermore, we confirmed that CDK13 gene copy number was significantly associated with clinical onset age in patients with HCC (P = 0.0037). Taken together, our results suggest that coincidently amplified CDK13, GMNN, and CENPF genes can play a role as common cancer-driver genes in human cancers.