Dietary sodium intake in young Korean adults and its relationship with eating frequency and taste preference

Dietary sodium intake is considered one of the major causal factors for hypertension. Thus, to control the increase of blood pressure and reduce the risk of hypertension-related clinical complications, a reduction in sodium intake is recommended. The present study aimed at determining the association of dietary sodium intake with meal and snack frequency, snacking time, and taste preference in Korean young adults aged 20-26 years, using a 125-item dish-frequency questionnaire. The mean dietary sodium intakes of men and women were 270.6 mmol/day and 213.1 mmol/day, which were approximately 310% and 245% of the daily sodium intake goal for Korean men and women, respectively. Dietary sodium intake was positively correlated with systolic blood pressure in the total group, and BMI in the total and men-only groups. In the total and men-only groups, those who consumed meals more times per day consumed more dietary sodium, but the number of times they consumed snacks was negatively correlated with dietary sodium intake in the total, men-only, and women-only groups. In addition, those who consumed snacks in the evening consumed more sodium than those who did so in the morning in the men-only group. The sodium intake was also positively associated with preference for salty and sweet taste in the total and women-only groups. Such a high intake of sodium in these young subjects shows that a reduction in sodium intake is important for the prevention of hypertension and related diseases in the future.

Identification and Characterization of Human Genes Targeted by Natural Selection

The human genome has evolved as a consequence of evolutionary forces, such as natural selection. In this study, we investigated natural selection on the human genes by comparing the numbers of nonsynonymous(NS) and synonymous (S) mutations in individual genes. We initially collected all coding SNP data of all human genes from the public dbSNP. Among the human genes, we selected 3 different selection groups of genes: positively selected genes (NS/S > or = 3), negatively selected genes (NS/S < or = 1/3) and neutral selection genes (0.9 < NS/S < 1.1). We characterized human genes targeted by natural selection. Negatively selected human genes were markedly associated with disease occurrence, but not positively selected genes. Interestingly, positively selected genes displayed an increase in potentially deleterious nonsynonymous SNPs with an increased frequency of tryptophan and tyrosine residues, suggesting a correlation with protective effects against human disease. Furthermore, our nonsynonymous/synonymous ratio data imply that specific human genes, such as ALMS1 and SPTBN5 genes, are differentially selected among distinct populations. We confirmed that inferences of natural selection using the NS/S ratio can be used extensively to identify functional genes selected during the evolutionary adaptation process.

Protein Tyrosine Phosphatase N1 Gene Variants Associated with Type 2 Diabetes Mellitus and Its Related Phenotypes in the Korean Population

Protein phosphorylation at tyrosine residues is a key regulatory event that modulates insulin signal transduction. We studied the PTPN1 gene with regard to susceptibility to Korean type 2 diabetes mellitus (T2DM) and its related quantitative traits. A total of seven SNPs [g.36171G>A (rs941798), g.58166G>A (rs3787343), g.58208A>G (rs2909270), g.64840C>T (rs754118), g.69560C>G (rs6020612), g.69866G>A (rs718050), and g.69934T>G (rs3787343)] were selected based on frequency (>0.05), linkage disequilibrium (LD) status, and haplotype tagging status. We studied the seven SNPs in 483 unrelated patients with type 2 diabetes (age: 64+/-2.8 years, onset age: 56+/-8.1 years; 206 men, 277 women) and 1138 nondiabetic control subjects (age: 64+/-2.9; 516 men, 622 women). The SNP rs941798 had protective effects against T2DM with an odds ratio of 0.726 (C.I. 0.541~0.975) and p-value=0.034, but none of the remaining six SNPs was associated with T2DM. Also, rs941798 was associated with blood pressure, HDL cholesterol, insulin sensitivity. rs941798 also has been associated with T2DM in previous reports of Caucasian-American and Hispanic-American populations. This is the first report that shows an association between PTPN1 and T2DM in the Korean as well as Asian population.

Putative association of RUNX1 polymorphisms with IgE levels in a Korean population

RUNX1, a member of the runt domain gene family of transcription factors, encodes a heterodimeric transcription factor and regulates the expression of various genes related to hematopoiesis and myeloid differentiation. RUNX1 has been one of the target genes for research into various autoimmune diseases due to its properties as a transcription factor and functional distribution for chromosomal translocation. In an effort to identify additional gene polymorphisms in which variants have been implicated in asthma, we investigated the genetic polymorphisms in RUNX1 to evaluate it as a potential candidate gene for a host genetic study of asthma and IgE production. We identified 19 sequence variants by direct DNA sequencing in 24 individuals of which four common variants were selected for genotyping in our asthma cohort (1,055 asthmatic patients, 384 normal controls). Using logistic regression analysis for association with the risk of asthma, while controlling for age, gender, and smoking status as covariates, no significant associations with the risk of asthma were detected. However, two polymorphisms in the promoter region (-2084G>C and -1282G>A) showed a marginal association with total IgE levels (0.03 and 0.03 in recessive models, respectively). Our findings suggest that polymorphisms in RUNX1 might be one of the genetic factors for the regulation of IgE production.

Genetic Variants of IL-13 and IL-4 in the Korean Population: Polymorphisms, Haplotypes and Linkage Disequilibrium

Asthma is an inflammatory airways disease characterized by bronchial hyperresponsiveness and airways obstruction, which results from a complex interaction of genetic and environmental factors. Interleukin (IL)-13 and IL-4 are important in IgE synthesis and allergic inflammation, therefore genes encoding IL-13 and IL-4 are candidates for predisposition to asthma. In the present study, we screened single-nucleotide polymorphisms (SNPs) in IL-13 and IL-4 and examined whether they are risk factors for asthma. We resequenced all exons and the promoter region in 12 asthma patients and 12 normal controls, and identified 18 SNPs including 2 novel SNPs. The linkage disequilibrium(LD) pattern was evaluated with 16 common SNPs, and haplotypes were also estimated within the block. Although IL-13 and IL-4 are localized within 27 kb on chromosome 5q31 and share many biological profiles, this region was partitioned into 2 blocks. One SNP and three SNPs were determined as haplotype-taggingSNPs (htSNPs) within IL-13 and IL-4 haplotype-block, respectively. No significant associations were observed between any of the SNPs or haplotypes and development of asthma in small number of Korean subjects. However, the genetic variants of IL-13 and IL-4 would provide valuable strategies for the genotyping studies in large population.

Prothrombin T165M and the Factor V R485K Polymorphism are Associated with an Increase Risk of Coronary Artery Disease in Koreans

BACKGROUND AND OBJECTIVES: An increased coagulation activity and an impaired antithrombotic function are associated with coronary artery disease (CAD). The purpose of this study was to evaluate whether the genetic variations in the prothrombin and factor V genes are associated with CAD. SUBJECTS AND METHODS: One hundred twenty eight patients having CAD and 168 healthy controls participated in this study. 98 of the CAD patients, who were not taking anticoagulant drugs, and 132 controls were analyzed for their prothrombin (PT) and factor V (FV) coagulant activity. The genotype was determined by the SNP-IT method. RESULTS: The genetic variation for the PT G2210A and FV R506Q (Leiden) was not detected in our standard samples. The genotype frequency of the T165M polymorphism in the PT gene of the CAD were not different from those of the control group. However, logistic regression analysis showed that 165MM genotype of the PT 165M polymorphism is associated with CAD independently (Odds ratio 1.82, 95% confidence interval; 1.04-3.16). Subjects with 165MM homozygote had higher PT activity than those with the 165T carrier in the both groups (p<0.05). The prevalence of the RR+RK genotype in the factor V R485K polymorphism was significantly higher in CAD group than in the control group (92% in CAD vs. 82% in control, p=0.012). From the multivariate analysis, the odds ratio of the 485K carrier was 2.48 for CAD (95% confidence interval: 1.87-5.66), in relation to the control subjects. No significant influence was seen of the factor V R485K polymorphism on corresponding mean factor V activity in control group. CONCLUSION: The PT 165MM genotype was linked with elevated levels of PT activity. The PT T165M and FV R485K polymorphisms were associated with CAD in Koreans.