Resources and Pilot Results for Establishing a Mongolian Twin Register

Gombojav, Bayasgalan,Damdinbazar, Otgonbayar,Danshiitsoodol, Narandalai,Dagvasumberel, Gonchigsuren,Purevdorj, Erkhembulgan,Gombojav, Enkhtsetseg,Chuluunbaatar, Urjinbadam,Ochir, Chimedsuren,Ichinkhor Cambridge University Press 2013 TWIN RESEARCH AND HUMAN GENETICS - Vol.16 No.1

<P>Despite the need to provide evidence-based health policy, most developing countries suffer from a lack of resources for sound epidemiologic evidence. Most twin registers have been established in developed countries and there are relatively fewer twin registers in developing countries. Considering the immense potential of twin research, it will be worthwhile to attempt to establish a new twin register in Mongolia, where biomedical studies are still scarce. Our objectives were to initiate the process of establishing a nation-wide twin register in Mongolia, based on a nation-wide, population-based database. With the approval and support of the Ministry of Population Development and Social Welfare of Mongolia, we were able to access an initial list of 411 twin pairs who live in the district of Ulaanbaatar, the capital city of Mongolia. By developing a questionnaire to estimate zygosity, we conducted a pilot survey. Those who registered consisted of 822 individuals or 411 twin pairs (same sex: male - 178; female - 157; different sex - 76), two sets of triplets (same sex: female - 2). The age of twins ranged from 1 to 81 (mean age 7.3 ± 11.3), and 52.4% were males. The first twin survey in Mongolia not only resulted in interim data for the Mongolian Twin Register, but has the potential for establishing a larger register by using the national database. It has been proven possible to establish a twin register for research purposes in Mongolia.</P>

Multiple susceptibility loci at chromosome 11q23.3 are associated with plasma triglyceride in East Asians

Gombojav, Bayasgalan,Lee, Soo Ji,Kho, Minjung,Song, Yun-Mi,Lee, Kayoung,Sung, Joohon American Society for Biochemistry and Molecular Bi 2016 Journal of lipid research Vol.57 No.2

<P>Genetic studies of plasma TG levels have identified associations with multiple candidate loci on chromosome11q23.3, which harbors a number of genes, including BUD13, ZNF259, and APOA5-A4-C3-A1. This study aimed to examine whether these multiple candidate genes on the 11q23.3 regions exert independent effects on TG levels or whether their effects are confounded by linkage disequilibrium (LD). We performed a genome-wide association study and consequent fine-mapping analyses on TG levels in two Korean population-based cohorts: the Korea Association Resource study (n = 8,223) and the Healthy Twin study (n = 1,735). A total of 301 loci reached genome-wide significance level in pooled analysis, including 10 SNPs with weak LD (r(2) < 0.06) clustered on 11q23.3: ApoA5 (rs651821, rs2075291); ZNF259 (rs964184, rs603446); BUD13 (rs11216126); Apoa4 (rs7396851); SIK3 (rs12292858); PCSK7 (rs199890178); PAFAH1B2 (rs12420127), and SIDT2 (rs2269399). When the inter-dependence between alleles was examined using conditional models, five loci on BUD13, ZNF259, and ApoA 5 showed possible independent associations. A haplotype analysis using five SNPs revealed both hyper-and hypotriglyceridemic haplotypes, which are relatively common in Koreans (haplotype frequency 0.08-0.22). Our findings suggest the presence of multiple functional loci on 11q23.3, which might exert their effects on plasma TG level independently or through complex interactions between functional loci.</P>

The Healthy Twin Study, Korea Updates: Resources for Omics and Genome Epidemiology Studies

Gombojav, Bayasgalan,Song, Yun-Mi,Lee, Kayoung,Yang, Sarah,Kho, Minjung,Hwang, Yong-Chul,Ko, Gwangpyo,Sung, Joohon Cambridge University Press 2013 TWIN RESEARCH AND HUMAN GENETICS - Vol.16 No.1

<P>The Healthy Twin Study, Korea (HT) is an ongoing multi-center cohort study that was initiated in 2005, based on a nation-wide twin and family database. Since its inception, the HT has recruited 815 pairs of adult twins and a total of 3,690 individual twins and their families as of July 2012. Here we summarize updates since the previous report in 2006. Besides the increase in size, the HT has been enriched in several aspects: a biobank was constructed for ongoing and future omics studies; and genome-wide single nucleotide polymorphism markers (Affymetrix GeneChip version 6.0, 1 M probes) have been analyzed for 2,200 individuals, which enabled gene identification studies for measured phenotypes. In addition, longitudinal study protocols were established through the HT and a second wave survey was finished in 2010 with >70% follow-up rate. The parallel genome research projects were recently launched, which would expedite multi-omics studies maximizing the twin potentials such as metagenomics and epigenetics studies, and endow us with resources for recruiting more participants. We submit this report to share updates and research opportunities from the HT.</P>

Combined effects of cognitive impairment and hypertension on total mortality in elderly people: the Kangwha Cohort study.

Gombojav, Bayasgalan,Yi, Sang-Wook,Sull, Jae Woong,Nam, Chung Mo,Ohrr, Heechoul Karger 2011 Gerontology Vol.57 No.6

<P>Previous studies have shown links between cognitive impairment and hypertension as well as mortality. However, combined effects of these two conditions on mortality have not been fully explored.</P>

Collective Betweenness Centrality in Networks

Gantulga Gombojav,Dalaijargal Purevsuren,Nyamlkhagva Sengee 한국멀티미디어학회 2022 The journal of multimedia information system Vol.9 No.2

The shortest path betweenness value of a node quantifies the amount of information passing through the node when all the pairs of nodes in the network exchange information in full capacity measured by the number of the shortest paths between the pairs assuming that the information travels in the shortest paths. It is calculated as the cumulative of the fractions of the number of shortest paths between the node pairs over how many of them actually pass through the node of interest. It’s possible for a node to have zero or underrated betweenness value while sitting just next to the giant flow of information. These nodes may have a significant influence on the network when the normal flow of information is disrupted. We propose a betweenness centrality measure called collective betweenness that takes into account the surroundings of a node. We will compare our measure with other centrality metrics and show some applications of it.

Heritability and linkage study on heart rates in a Mongolian population

Bayasgalan Gombojav,박한수,김종일,주영석,성주헌,조성일,이미경,Heechoul Ohrr,Janchiv Radnaabazar,서정선 생화학분자생물학회 2008 Experimental and molecular medicine Vol.40 No.5

Elevated heart rate has been proposed as an independent risk factor for cardiovascular diseases, but their interrelationships are not well understood. In this study, we performed a genome-wide linkage scan in 1,026 individuals (mean age 30.6 years, 54.5% women) from 73 extended families of Mongolia and determined quantitative trait loci that influence heart rate. The DNA samples were genotyped using deCODE 1,039 microsatellite markers for 3 cM density genome-wide linkage scan. Correlation analysis was carried out to evaluate the correlation of the covariates and the heart rate. T-tests of the heart rate were also performed on sex, smoking and alcohol intake. Consequently, this model was used in a nonparametric genome-wide linkage analysis using variance component model to create a multipoint logarithm of odds (LOD) score and a corresponding P value. In the adjusted model, the heritability of heart rate was estimated as 0.32 (P < .0001) and a maximum multipoint LOD score of 2.03 was observed in 77 cM region at chromosome 18. The second largest LOD score of 1.52 was seen on chromosome 5 at 216 cM. Genes located on the specified locations in chromosomes 5 and 18 may be involved in the regulation of heart rate.

Modifying Effects of Resting Heart Rate on the Association of Binge Drinking With All-cause and Cardiovascular Mortality in Older Korean Men: the Kangwha Cohort Study

Ryu, Mikyung,Gombojav, Bayasgalan,Nam, Chung Mo,Lee, Yunhwan,Han, Kimyoung Japan Epidemiological Association 2014 Journal of epidemiology Vol.24 No.4

<P><B>Background</B></P><P>Although binge drinking and high resting heart rate independently affect cardiovascular and all-cause mortality risk, the combined effect of these two risk factors and their interaction has rarely been studied. This study examined the association between binge drinking and cardiovascular and all-cause mortality and evaluated the potential modifying effect on this association of resting heart rate in Korean men.</P><P><B>Methods</B></P><P>Men aged 55 years or older in 1985 (<I>n</I> = 2600) were followed for cardiovascular and all-cause mortality for 20.8 years, until 2005. We estimated hazard ratios (HRs) for cardiovascular and all-cause mortality by binge drinking and resting heart rate using the Cox proportional hazard model.</P><P><B>Results</B></P><P>Heavy binge drinkers (≥12 drinks on one occasion) with elevated resting heart rate (≥80 bpm) had a HR of 2.25 (95% confidence interval [CI], 1.47–3.45) for death from cardiovascular disease and 1.37 (95% CI, 0.87–2.14) for all-cause mortality compared to the reference group (non-drinking and resting heart rate 61–79 bpm). The HRs of dying from cardiovascular disease increased linearly from 1.36 to 1.52, 1.71, and 2.25 among individuals with resting heart rate greater than or equal to 80 bpm within the four alcohol consumption categories (non-drinking, non-binge, moderate binge, and heavy binge), respectively.</P><P><B>Conclusions</B></P><P>Our findings suggest that, among older Korean men, heavy binge drinkers with an elevated resting heart rate are at high risk for cardiovascular and all-cause mortality.</P>

Population Based Study of the Association Between Binge Drinking and Mortality from Cancer of Oropharynx and Esophagus in Korean Men: the Kangwha Cohort Study

Jung, Sang Hyuk,Gombojav, Bayasgalan,Park, Eun-Cheol,Nam, Chung Mo,Ohrr, Heechoul,Won, Jong Uk Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.8

We assessed the association between frequency of heavy binge drinking and mortality from oropharynx and esophagus cancer after controlling for the total volume of alcohol intake among Korean men. The cohort comprised 2,677 male residents in Kangwha County, aged 55 or older in March 1985, for their upper digestive tract cancer mortality for 20.8 years up to December 31, 2005. For daily binge drinkers versus non-drinkers, the hazard ratios (95% Cls) for mortality were 4.82 (1.36, 17.1) and 6.75 (1.45, 31.4) for oropharyngeal and esophageal cancers, respectively. Even after adjusting for the volume of alcohol intake, we found the hazard ratios for frequency of binge drinking and mortality of oropharyngeal or esophageal cancer to not change appreciably: the hazard ratios were 4.90 (1.00, 27.0) and 7.17 (1.02, 50.6), respectively. For esophageal cancer, there was a strong dose-response relationship. The frequency of heavy binge drinking and not just the volume of alcohol intake may increase the risk of mortality from upper digestive tract cancer, particularly esophageal cancer in Korean men. These findings need to be confirmed in further studies with a larger sample size.

Genome-wide Linkage Study for Plasma HDL Cholesterol Level in an Isolated Population of Mongolia

Hansoo Park,김종일,Sung-Il Cho,Joohon Sung,Hyung-Lae Kim,Young Seok Ju,Gombojav Bayasgalan,이미경,서정선 한국유전체학회 2008 Genomics & informatics Vol.6 No.1

High-density lipoprotein (HDL) whose primary role is to transport cholesterol from peripheral tissues to the liver, is associated with the incidence of coronary heart disease. We analyzed HDL cholesterol levels in a genetically isolated population of extended Mongolian families. A total of 1002 individuals (54.5% women) from 95 families were enrolled. After genotyping by use of 1000 microsatellite markers, we performed a genome-wide linkage search with variance component analysis. The estimated heritability of HDL cholesterol was 0.45, revealing that HDL cholesterol was under significant genetic influence. We found peak evidence of linkage (LOD score=1.88) for HDL cholesterol level on chromosome 6 (nearest marker D6S1660) and potential evidences for linkage on chromosomes 1, 12 and 19 with the LOD scores of 1.32, 1.44 and 1.14, respectively. These results should pave the way for the discovery of the relevant genes by fine mapping and association analysis.

Genome-wide Linkage Study for Plasma HDL Cholesterol Level in an Isolated Population of Mongolia

Park, Han-Soo,Kim, Jong-Il,Cho, Sung-Il,Sung, Joo-Hon,Kim, Hyung-Lae,Ju, Young-Seok,Bayasgalan, Gombojav,Lee, Mi-Kyeong,Seo, Jeong-Sun Korea Genome Organization 2008 Genomics & informatics Vol.6 No.1

High-density lipoprotein (HDL) whose primary role is to transport cholesterol from peripheral tissues to the liver, is associated with the incidence of coronary heart disease. We analyzed HDL cholesterol levels in a genetically isolated population of extended Mongolian families. A total of 1002 individuals (54.5% women) from 95 families were enrolled. After genotyping by use of 1000 microsatellite markers, we performed a genome-wide linkage search with variance component analysis. The estimated heritability of HDL cholesterol was 0.45, revealing that HDL cholesterol was under significant genetic influence. We found peak evidence of linkage (LOD score=1.88) for HDL cholesterol level on chromosome 6 (nearest marker D6S1660) and potential evidences for linkage on chromosomes 1, 12 and 19 with the LOD scores of 1.32, 1.44 and 1.14, respectively. These results should pave the way for the discovery of the relevant genes by fine mapping and association analysis.