Genetic variations in the leptin and leptin receptor genes are associated with type 2 diabetes mellitus and metabolic traits in the Korean female population.

Type 2 diabetes mellitus (T2DM) is a metabolic disorder that is characterized by insulin resistance and hyperglycemia. Leptin inhibits the glucose-stimulated insulin secretion, and leptin receptors are present on beta cells as well as on fat cells, thus enabling leptin to modulate both insulin secretion and action. Therefore, leptin (LEP) and leptin receptor (LEPR) genes could play a role in the regulation of glucose and insulin after an oral glucose load. For the association study of LEP and LEPR with T2DM and metabolic traits, 752 women from Seoul National University Hospital (SNUH data) and 532 women from the Korean Health and Genome Study (KHGS data) were selected. Using the SNUH data, we identified that LEP-632G>A and +4998A>C polymorphisms were marginally associated with T2DM, LEP+4950G>A was significantly associated with several metabolic traits, and LEPR+5193G>A, +7187A>C, +27265G>A, +35861T>C, and +52289A>G showed strongly significant association with body mass index (BMI). We observed reproducibility of these results using the KHGS data; LEP+4950G>A and +4998A>C were significantly associated with systolic blood pressure and low-density lipoprotein cholesterol level, respectively. In conclusion, we observed that several polymorphisms in LEPR that had previous reports of association with BMI were significantly replicated in our samples and newly found that some variations of LEP were associated with T2DM and metabolic traits.

Identification of stathmin 1 expression induced by Epstein-Barr virus in human B lymphocytes.

INTRODUCTION: The Epstein-Barr virus transforms resting B cells into proliferating lymphoblastoid cells, the origin of cell lines. METHOD AND RESULTS: Our cDNA microarray analyses led to the identification of 232 up-regulated and 112 down-regulated genes with more than a 3-fold difference in lymphoblastoid cell lines compared to resting B cells. The functional classification of these genes exhibited the distinct expression signature for cell proliferation, cell cycle and an immune response. Among them, we verified the differential expression of several oncogenes such as stathmin 1 (STMN1), RAB27A, RAB9A, BACH1 and BACH2 using quantitative real-time reverse transcriptase-polymerase chain reactions or Western blot analysis. Expression of STMN1 (which is involved in regulation of the microtubule filament system, cell growth and S-phase of cell cycle) was increased in lymphoblastoid cell line as well as in 7-day post-Epstein-Barr virus infection B cells, compared to resting B cells. CONCLUSION: Thus, this study suggests that Epstein-Barr virus infection induces STMN1 expression, which play a role in cell cycle progression and proliferation in the human B lymphocyte.

A promoter nucleotide variant of the dendritic cell-specific DCNP1 associates with serum IgE levels specific for dust mite allergens among the Korean asthmatics.

Dendritic cells (DCs), the most abundant antigen-presenting cells in the lung, have been drawing attention for their roles in specific allergic responses to aeroallergens with support of Th lymphocytes, and in persistent inflammatory changes in allergic asthma. To identify genetic factors that may be involved in the asthma susceptibility and development of the disease phenotypes, we examined association of DC-specific DCNP1 polymorphisms with the disease risk. The case-control study revealed association of the nucleotide variants with serum immunoglobulin E (IgE) levels specific for Dermatophagoides farinae (Der f 1) and Dermatophagoides pteronyssinus (Der p 1), major aeroallergens of dust mites, among subjects with asthma. In particular, the T-allele-carrying genotype frequencies for one of the variants (c.-1289C>T) located in the promoter region were found increased in the asthmatic group with low levels of the mite-specific IgE (odds ratio (OR)=0.63 (0.48-0.83) for Der p 1). Results from functional analyses indicated that the promoter variant would affect the gene expression by modulating DNA-protein interaction. We propose that the genetic polymorphism of DCNP1 may influence production of specific IgE by altering DC functions in the mite allergen presenting and/or processing. The functional relevance of the genetic variation would provide an important insight into the genetic basis of allergic response to the mite antigens.

Validation and reproducibility of food frequency questionnaire for Korean genome epidemiologic study.

OBJECTIVE: To evaluate validity and reliability of the food-frequency questionnaire (FFQ) developed for the Korean Genome Epidemiologic Study (KoGES). METHODS: FFQ was administered twice at 1-year interval (first FFQ (FFQ1) at the beginning and second FFQ (FFQ2) at the end of the study) and diet records (DRs) were collected for 3 days during each of the four seasons from December 2002 to May 2004 for those who attended the health examination center. At the end of the study period, we collected the 12-day DRs of 124 participants. The nutrient intakes from the DRs were compared with both FFQ1 and FFQ2. RESULTS: The intakes of energy and some nutrients estimated from FFQ1 and FFQ2 were different from those assessed by the DRs. Especially, the consumption of carbohydrates was higher in FFQ1 and FFQ2 than in the DRs. The de-attenuated, age, sex and energy intake adjusted correlation coefficients between the FFQ2 and the 12-day DRs in Korean population ranged between 0.23 (Vitamin A) and 0.64 (carbohydrate). The median for all nutrients was 0.39. The correlations were similar when we compared nutrient densities of both methods. Joint classification of calorie-adjusted nutrient intakes assessed by FFQ2 and 12-day DRs by quartile ranged from 25.8% (vitamin A) to 39.5% (carbohydrate, iron) for exact concordance. Except vitamin A, the proportion of subjects classified into distant quartile was less than 7% in all nutrients. The median of correlations between the two FFQs 1 year apart were 0.45 for all nutrient intakes and 0.39 for nutrient densities. CONCLUSIONS: We conclude that the FFQ we have developed appears to be an acceptable tool for assessing the nutrient intakes in this population. Further studies for calibration of the FFQ collected from multicenters participating in the KoGES are needed. SPONSORSHIP: This study was supported by the budget of the National Genome Research Institute, Korea National Institute of Health (2002-347-6111-221).

The local prevalence of COPD by post-bronchodilator GOLD criteria in Korea.

OBJECTIVE: Chronic obstructive pulmonary disease (COPD) is a disease characterised by not fully reversible airflow limitation. The Global Initiative for Chronic Obstructive Lung Disease (GOLD) committee decided to diagnose COPD using post-bronchodilator spirometry values. We aimed to examine the prevalence and risk factors of COPD in Ansan, an industrialised city of Korea, by using the post-bronchodilator GOLD criteria. We then investigated the implications of brenchodilation on the prevalence of COPD. DESIGN: A total of 3642 participants in the Korean Health and Genome Study were interviewed about age, income, smoking status and respiratory symptoms and completed pulmonary function tests, including postbronchodilator spirometry. RESULTS: COPD prevalence by post-bronchodilator spirometry was 3.7% (134/3642), which was significantly different from that estimated using pre-bronchodilator criteria (7.7%, 282/3642). Exclusion of subjects with significant bronchodilator response (BDR) significantly lowered the prevalence of COPD to 3.3% (117/3572), compared with including subjects with post-bronchodilatory residual obstruction with significant BDR. Prevalence was associated with old age, smoking history, male sex and respiratory symptoms. CONCLUSION: COPD prevalence by post-bronchodilator GOLD criteria was 3.7%, which was much lower than that of pre-bronchodilator criteria. The bronchodilator reversibility test substantially affects estimations of COPD prevalence.

Association of PLXNA2 polymorphisms with vertebral fracture risk and bone mineral density in postmenopausal Korean population.

INTRODUCTION: Plexin A2 (PLXNA2) is a receptor that recognizes secreted or membrane-bound semaphorin 3A, which is implicated in neural regulation of bone metabolism. MATERIALS AND METHODS: In the present study, we identified 48 genetic polymorphisms in PLXNA2 by resequencing, and 10 single nucleotide polymorphisms (SNPs) were selected for further investigation into their potential involvement in osteoporosis in a postmenopausal population (n=560). RESULTS: Two SNPs, +14G>A (Gln5Arg) and +183429C>T (Tyr1621Tyr), and Block1-ht2 were associated with risk of vertebral fracture (p=0.01-0.05), and three SNPs, +799G>A (Ala267Thr), +135391G>A, and +190531G>C, were associated with bone mineral density at various femur sites (p=0.003-0.03). Particularly, the minor allele of +14G>A was associated with a protective effect on vertebral fracture and higher lumbar bone mineral density, suggesting that +14G>A may be a useful marker for osteoporosis and its related fracture. CONCLUSION: These results provide, for the first time, evidence supporting the association of PLXNA2 with osteoporosis in postmenopausal women.

Putative association of peroxisome proliferator-activated receptor gamma co-activator 1beta (PPARGC1B) polymorphism with Type 2 diabetes mellitus.

AIMS: Peroxisome proliferator-activated receptor gamma co-activator 1beta (PPARGC1B) may play an important role in obesity and Type 2 diabetes mellitus (T2DM). In an effort to identify genetic polymorphisms in potential candidate genes for T2DM, genetic associations of PPARGC1B were examined in a Korean T2DM study. METHODS: We have sequenced the PPARGC1B, and examined its association with T2DM and diabetic phenotypes in a Korean T2DM study (775 T2DM patients and 316 control subjects) using the TaqMan method. Logistic and multiple regression models were employed to analyse the genetic contributions of polymorphisms. Nineteen polymorphisms were identified in PPARGC1B. RESULTS: By logistic regression analysis controlling for age and sex as covariates, one non-synonymous single-nucleotide polymorphism (SNP; +102605C>A; Arg292Ser) in exon 5 showed marginal significant associations with the risk of T2DM. The allele frequency of the minor allele ['A (= Ser)' allele of +102605C>A] was lower among T2DM patients (frequency = 0.101) than among control subjects (frequency = 0.135) [P = 0.03, OR = 0.71 (95% CI: 0.51-0.94)]. Furthermore, serum triglyceride level was also associated with this non-synonymous SNP (+102605C>A; Arg292Ser) in exon 5 among controls (P = 0.03 in the dominant analysing model). Serum triglyceride levels [1.46 +/- 0.70 (log-transformed value; 0.12 +/- 0.18)] were lower in individuals who carry one or two copies of minor alleles than among others [1.60 +/- 0.85 (log-transformed value; 0.16 +/- 0.21)]. CONCLUSION: The present study provides, for the first time, information about genetic polymorphisms in PPARGC1B and putative associations of one non-synonymous SNP with the risk of T2DM and serum triglyceride (TG) levels in the Korean population, although this result was not significant after correction for multiple testing.

A rural-urban comparison of the characteristics of the metabolic syndrome by gender in Korea: the Korean Health and Genome Study (KHGS).

The number of cases of the metabolic syndrome is increasing dramatically in Western countries. However, the evaluation of the metabolic syndrome is limited in Asian countries. Thus, our objectives were: 1) to investigate parameters of the metabolic syndrome defined by the National Cholesterol Education Program (NCEP)-Adult Treatment Panel III (ATPIII) in the subjects representing Korean general population and 2) the modification of which factor is most effective in reducing the metabolic syndrome. A total of 10,044 (5024 rural and 5020 urban) Korean men and women in the age range 40-69 yr voluntarily participated in this community-based cross-sectional study (a rural and an urban community was selected). Anthropometric parameters (weight, height, waist and hip circumference and blood pressure), social factors (smoking, alcohol, exercise and education status) as well as biochemical parameters (fasting glucose and insulin, lipids and body composition) were measured. Twenty-six point one per cent of the total subjects were classified as having the metabolic syndrome. Age- and sex-adjusted prevalences were 29.3 and 22.3% in the rural and urban community, respectively (p< 0.01). Abdominal obesity (46.9%) and high blood pressure (45.2%) were major components in the rural community; hypertriglyceridemia (37.6%) and low HDL-cholesterolemia (37.0%) in the urban community. In conclusion, abdominal obesity in the rural community and dyslipidemia in the urban community should be a main subject of intervention, aimed at reducing the prevalence of the metabolic syndrome in Korea. Given the rapid progression of the Korean economy over the past 30 yr, the prevalence of the metabolic syndrome is expected to increase continuously. A strategy to prevent this expected extraordinary event should be conducted at a national level.

Common promoter polymorphism in monocyte differentiation antigen CD14 is associated with serum triglyceride levels and body mass index in non-diabetic individuals.

AIMS: Growing evidence supports the hypothesis that chronic low-grade inflammation related to innate immunity may play an important role in the pathophysiology of Type 2 diabetes mellitus (T2DM). The monocyte differentiation antigen CD14 gene (CD14) acts as the receptor for lipopolysaccharide (LPS) and augments monocyte/macrophage inflammatory responses. METHODS: We have sequenced the gene, including all exons, exon/intron boundaries, and the -1.5 kb of the 5' flanking region. Two common loci (minor allele frequency > 0.05) were genotyped in 775 T2DM patients and 316 control subjects recruited in the Korean T2DM Study. RESULTS: Eight polymorphisms, including four non-synonymous forms, were identified in CD14. No polymorphisms were found in association with T2DM. However, one common promoter SNP (-260T>C) was significantly associated with both the serum triglyceride level (TG) and body mass index (BMI) in non-diabetic control subjects. Individuals who carried the minor allele (C) had higher TG levels (1.65 +/- 0.81 vs. 1.46 +/- 0.80 mmol/l; P = 0.0007) and BMI (23.96 +/- 3.00 vs. 23.28 +/- 3.22 kg/m(2); P = 0.04) as compared with subjects carrying T/T genotypes. CONCLUSION: Our data suggest that lipid metabolism and obesity, important pathophysiological elements of T2DM and the metabolic syndrome, are regulated by complex mechanisms that include the CD14 gene polymorphism-mediated genetic propensity to non-specific inflammatory responses.

Prevalence of erectile dysfunction in Korean men with Type 2 diabetes mellitus.

AIMS: We investigated the prevalence and risk factors for developing erectile dysfunction (ED) in 1312 Korean men with diabetes in a multicentre study. METHODS: We used the modified International Index for Erectile Function-5 criteria to identify mild, moderate and complete ED. A standardized face-to-face questionnaire was used by trained interviewers, and validated against telephone interviews. We recorded the duration of diabetes, level of glycaemic control, vital signs, complications, exercise and alcohol and smoking habits, and diabetes treatments used. Results The mean age and median duration of diabetes were 53.8 +/- 6.65 and 6 years (range 1-43), respectively. The mean HbA(1c) and fasting glucose levels were 7.9 +/- 1.65% and 8.6 +/- 2.82 mmol/l, respectively. The overall prevalences of mild, moderate, complete ED and all ED (mild-to-complete) were 20.1, 19.5, 25.8 and 65.4%, respectively. ED was more common with age, reaching 79.3% in men aged > 60 years. Subjects aged > 60 years and with a duration of diabetes > 10 years were at greatest risk for all ED (OR = 10.4, 95% CI 5.8-18.5, P < 0.001) and complete ED (OR = 13.2, 95% CI 7.3-23.9, P < 0.001) when compared with the reference group (age 40-50 years with duration < 6 years). Age, duration of diabetes, HbA(1c), insulin use, neuropathy and macrovascular complications were positively associated with ED, but alcohol consumption and exercise habits were negatively associated. CONCLUSIONS: The prevalence of complete ED was approximately six times higher than in the general population.

Identification of four novel HLA-DOA alleles, DOA*010106, DOA*0102, DOA*0103, and DOA*0104N, by sequence-based typing*.

DOA sequences are currently known to have identical protein sequences. However, in this study, we report four novel allele types of human leucocyte antigen-DOA, including one synonymous and three non- synonymous amino acid changes from the Korean population. DOA*010106 has identical protein sequence with previously known DOA*010103 except one nucleotide difference at codon 45 (TCG-->TCA). In contrast, DOA*0102 and DOA*0103 have a sequence change at codon 99 (CTG-->GTG) and codon 105 (CGC-->TGC), causing non-synonymous amino acid changes, Leu99Val and Arg105Cys, respectively. In addition, DOA*0104N has a sequence deletion at codon 36 (CCC-->CC-), resulting in a frame shift leading to a stop codon at codon 62.

Geographical difference in the prevalence of isolated systolic hypertension in middle-aged men and women in Korea: the Korean Health and Genome Study.

To compare geographical difference in the prevalence of isolated systolic hypertension (ISH) in between urban (Ansan) and rural (Ansung) Korean adults aged 40-69 years, 4351 men and 4604 women enrolled in the Korean Health and Genome Study were analysed. Information was collected regarding gender, alcohol intake, smoking status, household income, occupation, and years of education by trained interviewers. Eligible subjects included untreated hypertensive and normotensive subjects. ISH was defined as a systolic blood pressure (SBP) > or = 140 mmHg and diastolic BP <90 mmHg. The overall age-adjusted prevalence of ISH was 4.1%. The prevalence of ISH in Ansung (5.7%) was higher than in Ansan (2.5%, P < 0.05). Also it increased with increments of age, from 1.0 to 12.8% in Ansung (P < 0.05) and from 0.3 to 13.0% in Ansan (P < 0.05). In those with body mass index (BMI) > or = 30.0 kg/m2 in Ansung, the prevalence of ISH in women was twice as much as in men. The prevalence of ISH in obese men and women with a waist-hip ratio > or =1.0 and > or = 0.85, respectively, was more than that of nonobese men and women in both areas. In Korea, because of industrialization, the age distribution was skewed and the Korean population in rural areas is more aged. ISH will become a truly major health problem in rural area, because ISH is related to age, BMI and waist-hip ratio. Therefore, the Korean government will be required to institute different policies in the hypertension management to target populations in rural and urban areas.

C-reactive protein level as an independent risk factor of metabolic syndrome in the Korean population. CRP as risk factor of metabolic syndrome.

Interrelationship between C-reactive protein (CRP) and metabolic syndrome (MS) was evaluated in a community-based cohort of 9773 Koreans aged 40-69 years. Metabolic syndrome was defined by criteria of the National Cholesterol Education Program. CRP was measured by validated high-sensitivity assay. The median CRP level was 1.4 mg/1, and significantly increased as the number of components of MS increased (P trend <0.001). CRP levels were significantly but marginally correlated with waist circumference (r=0.18), triglyceride (r=0.14), blood pressure (r=0.11), HDL-cholesterol (r=-0.10), and fasting glucose (r=0.09) (all P values<0.01). Odds ratios of the highest quartile of CRP for each component of MS; i.e., waist circumference, triglyceride, glucose metabolism, blood pressure, and HDL-cholesterol were 2.36, 1.79, 1.70, 1.32 and 1.28, respectively. The highest quartile of CRP was independently associated with 1.72-fold increased risk of MS in our logistic regression model adjusted for age, sex, BMI, and smoking. This study demonstrated that CRP is a strong associating factor of MS in Korean population. We recommend further evaluation of CRP levels in the other Asian ethnic groups to establish biological plausibility as the risk factor for MS in all ethnic groups.

Identification of a novel HLA-DQB1 allele, DQB1*0314, by sequence-based typing in the Korean population.

The polymorphism of HLA class II genes is largely confined to the exon 2 region. Sequence analysis of exon 2 of the DQB1 gene revealed the novel polymorphism in the Korean population. The new DQB1 allele, DQB1*0314, was differed from DQB1*0304 only at codon 46 (GAG-->GGG), corresponding to non-synonymous amino acid change (Glu-->Gly).

Identification of a novel HLA-DMB allele (DMB*0107) in the Korean population.

A novel allele for human leukocyte antigen-DMB was identified in the Korean population. DMB*0107 was identical to DMB*0101 at exon 2, apart from three mismatches at nucleotide positions 82 (A-->G), 146 (A-->T) and 212 (G-->A). These mutations resulted in codon changes at positions 10 (Thr-->Ala), 31 (Asp-->Val) and 53 (Ser-->Asn).

Identification of a novel HLA-DRB1*12 allele (DRB1*1210) in the Korean population.

At least 11 HLA-DRB1*12 alleles have been identified to date. We report a new HLA-DRB1*12 allele, DRB1*1210, that was identified in the Korean population. This new allele differs from HLA-DRB1*120101 by a single nucleotide at position 40 (G-->A) in exon 1 that falls within codon--16 (GTT-->ATT). This change results in a single valine to isoleucine amino acid alteration.

Prevalence and correlates of orthostatic hypotension in middle-aged men and women in Korea: the Korean Health and Genome Study.

To examine the prevalence and correlates of orthostatic hypotension (OH) in middle-aged adults enrolled in the Korean Health and Genome Study. Participants were 8908 individuals aged 40-69 years. Supine blood pressure (BP) was measured three times at 30-s intervals after at least 5 min of rest in the supine position and single standing BP was measured at 0 and 2 min after standing, respectively. OH was defined as a reduction in systolic BP or diastolic BP > or = 20 and 10 mmHg, respectively. The prevalence of OH at 0 and 2 min after standing was 12.3 and 2.9%, respectively. At 0 min of standing, OH frequency increased significantly with age from 6.4% in those aged 40-44 years to 23.1% in those aged 65-69 (P < 0.001). After adjustment for age and other characteristics, hypertension was associated with a 1.7-fold excess in the odds of OH in men and a 1.6-fold excess in women (P < 0.001). In contrast, an increase in body mass index (BMI) on the order of 5 kg/m2 was associated with a 20-30% reduction in the odds of OH (P < 0.001). Diabetes in women was also associated with a 1.4-fold excess in the odds of OH (P < 0.05). An increase in triglyceride by 136 mg/dl in men was associated with an increase in the odds of OH (P < 0.05). In conclusion, the prevalence and correlates of OH other than diabetes and triglycerides were notably similar in men and women. While the association between hypertension and OH has been observed elsewhere, low BMI in Korean adults with OH may be an important marker for subclinical morbidity or coexisting risk factors that need to be identified.

Short-term phytohaemagglutinin-activated mononuclear cells induce endothelial progenitor cells from cord blood CD34+ cells.

Endothelial progenitor cells (EPCs) were recently demonstrated to exist in human cord blood. Phytohaemagglutinin (PHA), a potent mitogen for mononuclear cells was used to induce EPCs from unsorted cord blood mononuclear cells (CBMCs). Adherent cells in clusters appeared approximately 24 h after CBMCs were cultured in plain Roswell Park Memorial Institute media containing 10% fetal bovine serum (culture media) and PHA. Adherent cells were further propagated for 1 week in plain culture media. Flow cytometry and Di-I staining analyses showed that CD45-, CD34+, Flk-1+, CD31+ or VE-cadherin+ EPCs were induced and that they were mainly from the CD34+ cell compartment. When enriched CD34+ cells alone were stimulated with culture supernatant of the PHA-activated CBMCs, they neither proliferated readily nor induced EPCs. Because EPCs first appeared within the clustering cells that expressed high levels of fibronectin and vascular endothelial growth factor (VEGF), our data suggest that both cell-cell/cell-matrix interaction and the local VEGF action are important in the induction of EPCs. Thus, we demonstrate for the first time that EPCs are induced from human cord blood stem cell populations that interact with neighbouring PHA-activated CBMCs. This finding may have a significant implication in inflammatory cell-mediated vasculogenesis and angiogenesis in vivo.

Identification of differentially expressed genes in normal and tumor human gastric tissue.

The search for differentially expressed genes in gastric cancer may help define molecular alterations and molecular diagnosis of gastric cancer. Using the differential display PCR technique, we identified 18 genes that are differentially expressed between normal and tumor human gastric tissues. Their expressions were verified with reverse Northern blot analysis and Northern blot analysis. Oxidative phosphorylation-related genes, antizyme inhibitor of ornithine decarboxylase, protein phosphatase-1beta, 35-kDa peroxisomal membrane protein, and cystic fibrosis transmembrane conductance receptor were highly expressed in tumor tissue, whereas pepsinogen A, Na-K ATPase alpha subunit, nerve growth factor receptor, and alpha-tropomyosin were highly expressed in normal tissue. In addition, 3 unknown genes were found to be differentially expressed in paired gastric tissues. These differentially expressed genes may provide significant opportunities for further understanding of gastric carcinogenesis and the molecular diagnosis of gastric cancer.

Glucose transporter 1 (GLUT1) expression is associated with intestinal type of gastric carcinoma.

Increased expression of glucose transporter1 (GLUT1) has been reported in many human cancers. We hypothesized that the degree of GLUT1 might provide a useful biological information in gastric adenocarcinoma. RT-PCR and immunostaining were used to analyze GLUT1 expression in gastric cancer. RT-PCR showed GLUT1 expression was not largely detected in normal gastric tissue but was detected in cancerous gastric tissue of counterpart. By immunohistochemistry, GLUT1 protein was absent in normal gastric epithelium and intestinal metaplasia. 11 of 65 patients with gastric adenocarcinoma had specific GLUT1 immunostaining in a plasma membrane pattern with varied intensities. GLUT1 protein did not show any significant correlation with tumor stage and nodal metastasis (p>0.05 by Mann-Whitney test). However, the positive immunostaining for GLUT1 is associated with intestinal differentiation (p=0.003). Our results suggest that GLUT1 protein is associated with intestinal type of gastric cancer.