Publications by authors named "Bok Ghee Han"

Advances in next-generation sequencing (NGS) technology have made personal genome sequencing possible, and indeed, many individual human genomes have now been sequenced. Comparisons of these individual genomes have revealed substantial genomic differences between human populations as well as between individuals from closely related ethnic groups. Transposable elements (TEs) are known to be one of the major sources of these variations and act through various mechanisms, including de novo insertion, insertion-mediated deletion, and TE-TE recombination-mediated deletion.

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Rheumatoid arthritis (RA) is a complex chronic systematic disease with progressive destruction of the joints by invasive synoviocytes. To characterize the key regulators involved in the development of RA, we obtained multilayer epigenomics data including DNA methylation by whole-genome bisulfite sequencing, miRNA profiles, genetic variations by whole-exome sequencing, and mRNA profiles from synoviocytes of RA and osteoarthritis (OA) patients. The overall DNA methylation patterns were not much different between RA and OA, but 523 low-methylated regions (LMRs) were specific to RA.

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We aggregated coding variant data for 81,412 type 2 diabetes cases and 370,832 controls of diverse ancestry, identifying 40 coding variant association signals (P < 2.2 × 10); of these, 16 map outside known risk-associated loci. We make two important observations.

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Myocardial infarction (MI) is a complex disease caused by combination of genetic and environmental factors. Although genome-wide association studies (GWAS) identified more than 46 risk loci which are associated with coronary artery disease and MI, most of the genetic variability inMI still remains undefined. Here, we screened the susceptibility loci for MI using exome sequencing and validated candidate variants in replication sets.

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To investigate the genetic basis of type 2 diabetes (T2D) to high resolution, the GoT2D and T2D-GENES consortia catalogued variation from whole-genome sequencing of 2,657 European individuals and exome sequencing of 12,940 individuals of multiple ancestries. Over 27M SNPs, indels, and structural variants were identified, including 99% of low-frequency (minor allele frequency [MAF] 0.1-5%) non-coding variants in the whole-genome sequenced individuals and 99.

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Lean body mass, consisting mostly of skeletal muscle, is important for healthy aging. We performed a genome-wide association study for whole body (20 cohorts of European ancestry with n = 38,292) and appendicular (arms and legs) lean body mass (n = 28,330) measured using dual energy X-ray absorptiometry or bioelectrical impedance analysis, adjusted for sex, age, height, and fat mass. Twenty-one single-nucleotide polymorphisms were significantly associated with lean body mass either genome wide (p < 5 × 10) or suggestively genome wide (p < 2.

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Differential DNA methylation with hyperglycemia is significantly associated with Type 2 Diabetes (T2D). Longtime extended exposure to high blood glucose levels can affect the epigenetic signatures in all organs. However, the relevance of the differential DNA methylation changes with hyperglycemia in blood with pancreatic islets remains unclear.

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Background: Genome-wide single marker and gene-based meta-analyses of long-term average (LTA) blood pressure (BP) phenotypes may reveal novel findings for BP.

Methods And Results: We conducted genome-wide analysis among 18 422 East Asian participants (stage 1) followed by replication study of ≤46 629 participants of European ancestry (stage 2). Significant single-nucleotide polymorphisms and genes were determined by a <5.

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Article Synopsis
  • Researchers analyzed genetic data from over 39,000 people to find new associations linked to glycemic traits and type 2 diabetes risk.
  • They discovered a specific variant (p.Pro50Thr) that increases fasting plasma insulin levels by 12%, particularly in individuals of Finnish descent.
  • This variant is associated with lower insulin sensitivity and a slightly higher risk of developing type 2 diabetes, highlighting its functional impact in glucose regulation.
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Large-scale meta-analyses of genome-wide association studies (GWAS) have identified >175 loci associated with fasting cholesterol levels, including total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG). With differences in linkage disequilibrium (LD) structure and allele frequencies between ancestry groups, studies in additional large samples may detect new associations. We conducted staged GWAS meta-analyses in up to 69,414 East Asian individuals from 24 studies with participants from Japan, the Philippines, Korea, China, Singapore, and Taiwan.

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Here, we tested the performance of the mitochondrial DNA copy number (mtDNA-CN) in predicting future type 2 diabetes (n = 1108). We used the baseline clinical data (age, sex, body mass index, waist-to-hip ratio, systolic and diastolic blood pressure) and the mtDNA-CN, hemoglobin A (AC) levels and results of oral glucose tolerance test (OGTT) including fasting plasma glucose, 1-hour glucose, and 2-hour glucose levels, to predict future diabetes. We built a prediction model using the baseline data and the diabetes status at biannual follow-up of 8 years.

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The genetic architecture of common traits, including the number, frequency, and effect sizes of inherited variants that contribute to individual risk, has been long debated. Genome-wide association studies have identified scores of common variants associated with type 2 diabetes, but in aggregate, these explain only a fraction of the heritability of this disease. Here, to test the hypothesis that lower-frequency variants explain much of the remainder, the GoT2D and T2D-GENES consortia performed whole-genome sequencing in 2,657 European individuals with and without diabetes, and exome sequencing in 12,940 individuals from five ancestry groups.

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Objectives: The delayed separation of whole blood can influence the concentrations of circulating blood components, including metabolites and cytokines. The aim of this study was to determine whether clinical-biochemistry analytes can be used to assess the delayed separation of whole blood.

Methods: We investigated the plasma and serum concentrations of five clinical-biochemistry analytes and free hemoglobin when the centrifugation of whole blood stored at 4°C or room temperature was delayed for 4 hours, 6 hours, 24 hours, or 48 hours, and compared the values with those of matched samples that had been centrifuged within 2 hours after whole-blood collection.

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To increase our understanding of the genetic basis of adiposity and its links to cardiometabolic disease risk, we conducted a genome-wide association meta-analysis of body fat percentage (BF%) in up to 100,716 individuals. Twelve loci reached genome-wide significance (P<5 × 10(-8)), of which eight were previously associated with increased overall adiposity (BMI, BF%) and four (in or near COBLL1/GRB14, IGF2BP1, PLA2G6, CRTC1) were novel associations with BF%. Seven loci showed a larger effect on BF% than on BMI, suggestive of a primary association with adiposity, while five loci showed larger effects on BMI than on BF%, suggesting association with both fat and lean mass.

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Pre-analytical variations in plasma and serum samples can occur because of variability in whole-blood processing procedures. The aim of this study was to determine the impact of delayed separation of whole blood on the plasma and serum concentrations of cytokines. The concentrations of 16 cytokines were measured in plasma and serum samples when the centrifugation of whole blood at room temperature was delayed for 4, 6, 24, or 48 h, and the values were compared with those observed after separation within 2 h of whole-blood collection.

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Systemic lupus erythematosus (SLE) has a strong but incompletely understood genetic architecture. We conducted an association study with replication in 4,478 SLE cases and 12,656 controls from six East Asian cohorts to identify new SLE susceptibility loci and better localize known loci. We identified ten new loci and confirmed 20 known loci with genome-wide significance.

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Article Synopsis
  • The study identified new genetic loci linked to abdominal obesity traits (waist circumference and waist-hip ratio) in individuals of Asian descent, expanding on previous findings from European populations.
  • A meta-analysis of around 2.5 million SNPs led to the discovery of four new loci related to waist circumference and two to waist-hip ratio, as well as three additional waist circumference loci, with some findings adjusted for body mass index.
  • Functional analyses indicated that the newly identified loci are involved in key signaling pathways, enhancing the understanding of the genetic factors contributing to abdominal obesity.
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Introduction: Calcaneal quantitative ultrasound has been recognized as a non-invasive method for evaluation of bone strength and prediction of osteoporotic fracture.

Methods: To extend a thorough genetic catalog for osteoporotic bone properties, we performed a genome-wide association study (rural cohort I, n=1895) of speed of sound (SOS) using the 1000 genome-based imputation in the discovery stage and then carried out in silico lookups (rural cohort II and III, n=2,967) and de novo genotyping (rural cohort IV, n=4,296) in the replication stage.

Results: In the combined meta-analysis (n=9,158), we identified a novel variant associated with SOS (rs2445771 in the GLDN gene, P=2.

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Objective: Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder whose etiology is incompletely understood, but likely involves environmental triggers in genetically susceptible individuals. Using an unbiased genome-wide association (GWA) scan and replication analysis, we sought to identify the genetic loci associated with SLE in a Korean population.

Methods: A total of 1,174 SLE cases and 4,246 population controls from Korea were genotyped and analyzed with a GWA scan to identify single-nucleotide polymorphisms (SNPs) significantly associated with SLE, after strict quality control measures were applied.

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Postprandial hyperglycemia is known to be one of the earliest signs of abnormal glucose homeostasis associated with type 2 diabetes. This study aimed to assess clinical significance of a 1-h postprandial glucose level for the development of diabetes, and identify epigenetic biomarkers of postprandial hyperglycemia. We analyzed clinical data from the oral glucose tolerance tests for healthy subjects (n=4502).

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Copy number variation is a well-known genetic variation. microRNAs (miRNAs/miRs) are non-coding RNAs that mediate gene expression by regulating target mRNAs. In the present study, copy number deletions encompassing miRNA coding regions were investigated to determine the association between the deletion of miRNA and its phenotypic effects.

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