Effects of MTNR1B variants on fasting glucose levels in a Korean population

Fasting glucose level is the most basic and widely used indicator of diabetes. Several genome wide association studies have reported that the gene encoding melatonin receptor 1B (MTNR1B) exerts a major effect on serum fasting glucose levels. We tested for the association between single nucleotide polymorphisms (SNPs) in the MTNR1B gene and fasting glucose levels in a Korean population consisting of 8,229 subjects taken from two community-based cohorts. The mean age of the subjects in the study population was 51.9 years. For this study, we selected 363 SNPs located in the MTNR1B gene, which is located on chromosome 11. Multivariate linear regression models were used to test for genotypic effects on fasting glucose levels while adjusting for age and sex under an additive model. The MTNR1B SNP most highly associated with fasting glucose levels was rs10830962 (p=1.95×10^?5), followed by rs3847554 (p=3.16×10^?4). Replication of these initial findings is important to better understand the correlation between MTNR1B variations and their effects, especially in Asian populations.     

Polymorphisms within the Novel Type 2 Diabetes Risk Locus MTNR1B Determine β-Cell Function

Background

Very recently, a novel type 2 diabetes risk gene, i.e., MTNR1B, was identified and reported to affect fasting glycemia. Using our thoroughly phenotyped cohort of subjects at an increased risk for type 2 diabetes, we assessed the association of common genetic variation within the MTNR1B locus with obesity and prediabetes traits, namely impaired insulin secretion and insulin resistance.

Methodology/Principal Findings

We genotyped 1,578 non-diabetic subjects, metabolically characterized by oral glucose tolerance test, for five tagging single nucleotide polymorphisms (SNPs) covering 100% of common genetic variation (minor allele frequency >0.05) within the MTNR1B locus (rs10830962, rs4753426, rs12804291, rs10830963, rs3781638). In a subgroup (N = 513), insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamp, and in a further subgroup (N = 301), glucose-stimulated insulin secretion was determined by intravenous glucose tolerance test. After appropriate adjustment for confounding variables and Bonferroni correction for multiple comparisons, none of the tagging SNPs was reliably associated with measures of adiposity. SNPs rs10830962, rs4753426, and rs10830963 were significantly associated with higher fasting plasma glucose concentrations (p<0.0001) and reduced OGTT- and IVGTT-induced insulin release (p≤0.0007 and p≤0.01, respectively). By contrast, SNP rs3781638 displayed significant association with lower fasting plasma glucose levels and increased OGTT-induced insulin release (p<0.0001 and p≤0.0002, respectively). Moreover, SNP rs3781638 revealed significant association with elevated fasting- and OGTT-derived insulin sensitivity (p≤0.0021). None of the MTNR1B tagging SNPs altered proinsulin-to-insulin conversion.

Conclusions/Significance

In conclusion, common genetic variation within MTNR1B determines glucose-stimulated insulin secretion and plasma glucose concentrations. Their impact on β-cell function might represent the prevailing pathomechanism how MTNR1B variants increase the type 2 diabetes risk.     

Common Polymorphisms in MTNR1B,G6PC2 and GCK Are Associated with Increased Fasting Plasma Glucose and Impaired Beta-Cell Function in Chinese Subjects

Background

Previous studies identified melatonin receptor 1B (MTNR1B), islet-specific glucose 6 phosphatase catalytic subunit-related protein (G6PC2), glucokinase (GCK) and glucokinase regulatory protein (GCKR) as candidate genes for type 2 diabetes (T2D) acting through elevated fasting plasma glucose (FPG). We examined the associations of the reported common variants of these genes with T2D and glucose homeostasis in three independent Chinese cohorts.

Methodology/Principal Findings

Five single nucleotide polymorphisms (SNPs), MTNR1B rs10830963, G6PC2 rs16856187 and rs478333, GCK rs1799884 and GCKR rs780094, were genotyped in 1644 controls (583 adults and 1061 adolescents) and 1342 T2D patients. The G-allele of MTNR1B rs10830963 and the C-alleles of both G6PC2 rs16856187 and rs478333 were associated with higher FPG (0.0034<P<6.6×10⁻⁵) in healthy controls. In addition to our previous report for association with FPG, the A-allele of GCK rs1799884 was also associated with reduced homeostasis model assessment of beta-cell function (HOMA-B) (P = 0.0015). Together with GCKR rs780094, the risk alleles of these SNPs exhibited dosage effect in their associations with increased FPG (P = 2.9×10⁻⁹) and reduced HOMA-B (P = 1.1×10⁻³). Meta-analyses strongly supported additive effects of MTNR1B rs10830963 and G6PC2 rs16856187 on FPG.

Conclusions/Significance

Common variants of MTNR1B, G6PC2 and GCK are associated with elevated FPG and impaired insulin secretion, both individually and jointly, suggesting that these risk alleles may precipitate or perpetuate hyperglycemia in predisposed individuals.     

Association of genetic variants of melatonin receptor 1B with gestational plasma glucose level and risk of glucose intolerance in pregnant Chinese women

Background

This study aimed to explore the association of MTNR1B genetic variants with gestational plasma glucose homeostasis in pregnant Chinese women.

Methods

A total of 1,985 pregnant Han Chinese women were recruited and evaluated for gestational glucose tolerance status with a two-step approach. The four MTNR1B variants rs10830963, rs1387153, rs1447352, and rs2166706 which had been reported to associate with glucose levels in general non-pregnant populations, were genotyped in these women. Using an additive model adjusted for age and body mass index (BMI), association of these variants with gestational fasting and postprandial plasma glucose (FPG and PPG) levels were analyzed by multiple linear regression; relative risk of developing gestational glucose intolerance was calculated by logistic regression. Hardy-Weinberg Equilibrium was tested by Chi-square and linkage disequilibrium (LD) between these variants was estimated by measures of D′ and r².

Results

In the pregnant Chinese women, the MTNR1B variant rs10830963, rs1387153, rs2166706 and rs1447352 were shown to be associated with the increased 1 hour PPG level (p = 8.04×10⁻¹⁰, 5.49×10⁻⁶, 1.89×10⁻⁵ and 0.02, respectively). The alleles were also shown to be associated with gestational glucose intolerance with odds ratios (OR) of 1.64 (p = 8.03×10⁻¹¹), 1.43 (p = 1.94×10⁻⁶), 1.38 (p = 1.63×10⁻⁵) and 1.24 (p = 0.007), respectively. MTNR1B rs1387153, rs2166706 were shown to be associated with gestational FPG levels (p = 0.04). Our data also suggested that, the LD pattern of these variants in the studied women conformed to that in the general populations: rs1387153 and rs2166706 were in high LD, they linked moderately with rs10830963, but might not linked with rs1447352;rs10830963 might not link with rs1447352, either. In addition, the MTNR1B variants were not found to be associated with any other traits tested.

Conclusions

The MTNR1B is likely to be involved in the regulation of glucose homeostasis during pregnancy.     

Effects of GCK,GCKR, G6PC2 and MTNR1B Variants on Glucose Metabolism and Insulin Secretion

Background

Single nucleotide polymorphisms (SNPs) from GCK, GCKR, G6PC2 and MTNR1B were found to modulate the fasting glucose levels. The current study aimed to replicate this association in the Chinese population and further analyze their effects on biphasic insulin secretion.

Methods/Principal Findings

SNPs from GCK, GCKR, G6PC2 and MTNR1B were genotyped in the Shanghai Chinese, including 3,410 type 2 diabetes patients and 3,412 controls. The controls were extensively phenotyped for the traits related to glucose metabolism and insulin secretion. We replicated the association between GCK rs1799884, G6PC2 rs16856187 and MTNR1B rs10830963 and fasting glucose in our samples (p = 0.0003∼2.0×10⁻⁸). GCK rs1799884 and G6PC2 rs16856187 showed association to HOMA-β, insulinogenic index and both first- and second-phases insulin secretion (p = 0.0030∼0.0396). MTNR1B rs10830963 was associated to HOMA-β, insulinogenic index and first-phase insulin secretion (p = 0.0102∼0.0426), but not second-phase insulin secretion (p = 0.9933). Combined effect analyses showed individuals carrying more risk allele for high fasting glucose tended to have a higher glucose levels at both fasting and 2 h during OGTTs (p = 1.7×10⁻¹³ and 0.0009, respectively), as well as lower HOMA-β, insulinogenic index and both first- and second-phases insulin secretion (p = 0.0321∼1.1×10⁻⁷).

Conclusions/Significance

We showed that SNPs from GCK, G6PC2 and MTNR1B modulated the fasting glucose levels in the normoglycaemic population while SNPs from G6PC2 and GCKR was associated with type 2 diabetes. Moreover, we found GCK and G6PC2 genetic variants were associated to both first- and second-phases insulin secretion while MTNR1B genetic variant was associated with first-phase insulin secretion, but not second-phase insulin secretion.     

Large Scale Meta-Analyses of Fasting Plasma Glucose Raising Variants in GCK,GCKR, MTNR1B and G6PC2 and Their Impacts on Type 2 Diabetes Mellitus Risk

Background

The evidence that the variants GCK rs1799884, GCKR rs780094, MTNR1B rs10830963 and G6PC2 rs560887, which are related to fasting plasma glucose levels, increase the risk of type 2 diabetes mellitus (T2DM) is contradictory. We therefore performed a meta-analysis to derive a more precise estimation of the association between these polymorphisms and T2DM.

Methods

All the publications examining the associations of these variants with risk of T2DM were retrieved from the MEDLINE and EMBASE databases. Using the data from the retrieved articles, we computed summary estimates of the associations of the four variants with T2DM risk. We also examined the studies for heterogeneity, as well as for bias of the publications.

Results

A total of 113,025 T2DM patients and 199,997 controls from 38 articles were included in the meta-analysis. Overall, the pooled results indicated that GCK (rs1799884), GCKR (rs780094) and MTNR1B (rs10830963) were significantly associated with T2DM susceptibility (OR, 1.04; 95%CI, 1.01–1.08; OR, 1.08; 95%CI, 1.05–1.12 and OR, 1.05; 95%CI, 1.02–1.08, respectively). After stratification by ethnicity, significant associations for the GCK, MTNR1B and G6PC2 variants were detected only in Caucasians (OR, 1.09; 95%CI, 1.02–1.16; OR, 1.10; 95%CI, 1.08–1.13 and OR, 0.97; 95%CI, 0.95–0.99, respectively), but not in Asians (OR, 1.02, 95% CI 0.98–1.05; OR, 1.01; 95%CI, 0.98–1.04 and OR, 1.12; 95%CI, 0.91–1.32, respectively).

Conclusions

Our meta-analyses demonstrated that GCKR rs780094 variant confers high cross-ethnicity risk for the development of T2DM, while significant associations between GCK, MTNR1B and G6PC2 variants and T2DM risk are limited to Caucasians.     

Association of new loci identified in European genome-wide association studies with susceptibility to type 2 diabetes in the Japanese

Background

Several novel susceptibility loci for type 2 diabetes have been identified through genome-wide association studies (GWAS) for type 2 diabetes or quantitative traits related to glucose metabolism in European populations. To investigate the association of the 13 new European GWAS-derived susceptibility loci with type 2 diabetes in the Japanese population, we conducted a replication study using 3 independent Japanese case-control studies.

Methodology/Principal Findings

We examined the association of single nucleotide polymorphisms (SNPs) within 13 loci (MTNR1B, GCK, IRS1, PROX1, BCL11A, ZBED3, KLF14, TP53INP1, KCNQ1, CENTD2, HMGA2, ZFAND6 and PRC1) with type 2 diabetes using 4,964 participants (2,839 cases and 2,125 controls) from 3 independent Japanese samples. The association of each SNP with type 2 diabetes was analyzed by logistic regression analysis. Further, we performed combined meta-analyses for the 3 studies and previously performed Japanese GWAS data (4,470 cases vs. 3,071 controls). The meta-analysis revealed that rs2943641 in the IRS1 locus was significantly associated with type 2 diabetes, (P = 0.0034, OR = 1.15 95% confidence interval; 1.05–1.26) and 3 SNPs, rs10930963 in the MTNR1B locus, rs972283 in the KLF14 locus, and rs231362 in the KCNQ1 locus, had nominal association with type 2 diabetes in the present Japanese samples (P<0.05).

Conclusions

These results indicate that IRS1 locus may be common locus for type 2 diabetes across different ethnicities.     

Association between the Melatonin Receptor 1B Gene Polymorphism on the Risk of Type 2 Diabetes,Impaired Glucose Regulation: A Meta-Analysis

Background

Melatonin receptor 1B (MTNR1B) belongs to the seven-transmembrane G protein-coupled receptor superfamily involved in insulin secretion, which has attracted considerable attention as a candidate gene for type 2 diabetes (T2D) since it was first identified as a loci associated with fasting plasma glucose level through genome wide association approach. The relationship between MTNR1B and T2D has been reported in various ethnic groups. The aim of this study was to consolidate and summarize published data on the potential of MTNR1B polymorphisms in T2D risk prediction.

Methods

PubMed, EMBASE, ISI web of science and the CNKI databases were systematically searched to identify relevant studies. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated. Heterogeneity and publication bias were also tested.

Results

A total of 23 studies involving 172,963 subjects for two common polymorphisms (rs10830963, rs1387153) on MTNR1B were included. An overall random effects per-allele OR of 1.05 (95% CI: 1.02–1.08; P<10⁻⁴) and 1.04 (95% CI: 0.98–1.10; P = 0.20) were found for the two variants respectively. Similar results were also observed using dominant or recessive genetic model. There was strong evidence of heterogeneity, which largely disappeared after stratification by ethnicity. Significant results were found in Caucasians when stratified by ethnicity; while no significant associations were observed in East Asians and South Asians. Besides, we found that the rs10830963 polymorphism is a risk factor associated with increased impaired glucose regulation susceptibility.

Conclusions

This meta-analysis demonstrated that the rs10830963 polymorphism is a risk factor for developing impaired glucose regulation and T2D.     

Effects of Genetic Variants Previously Associated with Fasting Glucose and Insulin in the Diabetes Prevention Program

Common genetic variants have been recently associated with fasting glucose and insulin levels in white populations. Whether these associations replicate in pre-diabetes is not known. We extended these findings to the Diabetes Prevention Program, a clinical trial in which participants at high risk for diabetes were randomized to placebo, lifestyle modification or metformin for diabetes prevention. We genotyped previously reported polymorphisms (or their proxies) in/near G6PC2, MTNR1B, GCK, DGKB, GCKR, ADCY5, MADD, CRY2, ADRA2A, FADS1, PROX1, SLC2A2, GLIS3, C2CD4B, IGF1, and IRS1 in 3,548 Diabetes Prevention Program participants. We analyzed variants for association with baseline glycemic traits, incident diabetes and their interaction with response to metformin or lifestyle intervention. We replicated associations with fasting glucose at MTNR1B (P<0.001), G6PC2 (P = 0.002) and GCKR (P = 0.001). We noted impaired β-cell function in carriers of glucose-raising alleles at MTNR1B (P<0.001), and an increase in the insulinogenic index for the glucose-raising allele at G6PC2 (P<0.001). The association of MTNR1B with fasting glucose and impaired β-cell function persisted at 1 year despite adjustment for the baseline trait, indicating a sustained deleterious effect at this locus. We also replicated the association of MADD with fasting proinsulin levels (P<0.001). We detected no significant impact of these variants on diabetes incidence or interaction with preventive interventions. The association of several polymorphisms with quantitative glycemic traits is replicated in a cohort of high-risk persons. These variants do not have a detectable impact on diabetes incidence or response to metformin or lifestyle modification in the Diabetes Prevention Program.     

Genetic studies of the cystathionine beta-synthase gene and myelomeningocele

BACKGROUND: Among infants born with spina bifida, the most common defect is myelomeningocele (MM). The prevention of MM by maternal periconceptional folic acid (FA) supplementation has been studied extensively. The protective effect provided by FA suggests that the genes involved in folate metabolism, such as cystathionine beta‐synthase (CBS), warrant further investigation. METHODS: This study sequenced the DNA from 96 patients with MM to identify novel potential disease‐causing variants across the 17 exons of the CBS gene. The frequencies of known single nucleotide polymorphisms (SNPs) were identified, and sequences that differed from the reference sequences were considered novel variants. Statistical analysis was performed using two‐sided Fisher's exact test to compare frequencies of SNPs between groups of patients and the known population frequencies. RESULTS: We found a new variant in exon 3 in one patient that results in a G/A change subsequently encoding a stop codon. In addition, we found a new variant in the 3′‐UTR of exon 17. Allele frequencies for 10 known single nucleotide polymorphisms (SNPs) were determined: rs234706, rs72058776, rs1801181, rs6582281, rs71872941, rs12613, rs706208, rs706209, rs73906420, and rs9982921. Of the remaining 48 known SNPs, all tested DNAs were homozygous for the major allele. CONCLUSION: We identified a previously undescribed variant in exon 3 that encodes a stop codon, thus halting downstream translation of the CBS protein. According to the Human Splicing Finder, the 3′‐UTR variant found in exon 17 is predicted to abolish the recognition sites for two splice binding factors, SRp40 and SF2/ASF. The functional significance of the 3′‐UTR mutation needs to be investigated. Birth Defects Research (Part A), 2012. © 2011 Wiley Periodicals, Inc.     

Association Studies on Ghrelin and Ghrelin Receptor Gene Polymorphisms With Obesity

Ghrelin exerts a stimulatory effect on appetite and regulates energy homeostasis. Ghrelin gene variants have been shown to be associated with metabolic traits, although there is evidence suggesting linkage and association with obesity and the ghrelin receptor (GHSR). We hypothesized that these genes are good candidates for susceptibility to obesity. Direct sequencing identified 12 ghrelin single‐nucleotide polymorphisms (SNPs) and 8 GHSR SNPs. The 10 common SNPs were genotyped in 1,275 obese subjects and in 1,059 subjects from a general population cohort of European origin. In the obesity case‐control study, the GHSR SNP rs572169 was found to be associated with obesity (P = 0.007 in additive model, P = 0.001 in dominant model, odds ratio (OR) 1.73, 95% confidence interval (1.23–2.44)). The ghrelin variant, g.A265T (rs4684677), showed an association with obesity (P = 0.009, BMI adjusted for age and sex) in obese families. The ghrelin variant, g.A‐604G (rs27647), showed an association with insulin levels at 2‐h post‐oral glucose tolerance test (OGTT) (P = 0.009) in obese families. We found an association between the eating behavior “overeating” and the GHSR SNP rs2232169 (P = 0.02) in obese subjects. However, none of these associations remained significant when corrected for multiple comparisons. Replication of the nominal associations with obesity could not be confirmed in a German genome‐wide association (GWA) study for rs4684677 and rs572169 polymorphisms. Our data suggest that common polymorphisms in ghrelin and its receptor genes are not major contributors to the development of polygenic obesity, although common variants may alter body weight and eating behavior and contribute to insulin resistance, in particular in the context of early‐onset obesity.     

A functional variant in ST2 gene is associated with risk of hypertension via interfering MiR‐202‐3p

Recent studies have suggested that interleukin 1 receptor‐like 1 (ST2) plays a critical role in pathogenesis of several cardiovascular disease conditions. In this study, we examined association of 13 single nucleotide polymorphisms (SNPs) of ST2 gene with essential hypertension (EH) risk in 1151 patients with EH and 1135 controls. Our study showed that variants rs11685424, rs12999364 and rs3821204 are highly associated with an increase in risk of EH, while rs6543116 is associated with a decrease risk of EH. Notably, in silico analyses suggested the G>C change of rs3821204, which located within the 3′UTR of soluble ST2 mRNA, disrupted a putative binding site for miR202‐3p. Functional analyses suggested that miR‐202‐3p significantly decreased soluble ST2‐G mRNA stability and inhibited its endogenous expression. Furthermore, we found increased plasma‐soluble ST2 (sST2) level was highly associated with CC genotype of rs3821204 in vivo. Taken together, our findings provide the first evidence that genetic variants in ST2 gene are associated with EH risk and variant rs3821204 may influence the development of EH by controlling sST2 expression.     

Polymorphisms of the DNA repair gene EXO1 modulate cognitive aging in old adults in a Taiwanese population

Evidence indicates that the age-related neuropathological mechanisms associated with DNA repair genes may contribute to cognitive aging and Alzheimer’s disease. In this study, we hypothesize that single nucleotide polymorphisms (SNPs) within 155 DNA repair genes may be linked to cognitive aging independently and/or through complex interactions in an older Taiwanese population. A total of 3,730 Taiwanese subjects aged over 60 years from the Taiwan Biobank were analyzed. Mini-Mental State Examination (MMSE) was administered to all subjects, and MMSE scores were used to measure cognitive functions. Our data showed that out of 1,652 SNPs, the rs1776181 (P = 1.47 × 10⁻⁵), rs1776177 (P = 8.42 × 10^-7), rs1635510 (P = 7.97 × 10^-6), and rs2526698 (P = 7.06 × 10^-6) SNPs in the EXO1 gene were associated with cognitive aging. The association with these SNP remained significant after performing Bonferroni correction. Additionally, we found that interactions between the EXO1 and RAD51C genes influenced cognitive aging (P = 0.002). Finally, we pinpointed the influence of interactions between EXO1 and physical activity (P < 0.001) as well as between DCLRE1C and physical activity (P < 0.001). Our study indicated that DNA repair genes may contribute to susceptibility in cognitive aging independently as well as through gene-gene and gene-physical interactions.     

Analysis of FTO gene variants with measures of obesity and glucose homeostasis in the IRAS Family Study

Multiple studies have identified FTO gene variants associated with measures of adiposity in European-derived populations. The objective of the study was to determine whether FTO variants were associated with adiposity, including visceral and subcutaneous adipose tissue (VAT, SAT), and glucose homeostasis measures in the Insulin Resistance Atherosclerosis Family Study (IRASFS). A total of 27 SNPs in FTO intron 1, including SNPs prominent in the literature (rs9939609, rs8050136, rs1121980, rs17817449, rs1421085, and rs3751812), were genotyped in 1,424 Hispanic Americans and 604 African Americans. Multiple SNPs were associated with BMI and SAT (P values ranging from 0.001 to 0.033), and trending or associated with waist circumference (P values ranging from 0.008 to 0.099) in the Hispanic Americans. No association was observed with VAT, illustrating that FTO variants are associated with overall fat mass instead of specific fat depots. For the glucose homeostasis measures, variants were associated with fasting insulin but, consistent with other studies, after BMI adjustment, no evidence of association remained. The lack of association of FTO SNPs with insulin sensitivity is consistent with the lack of association with VAT, since these traits are strongly correlated. In the African Americans, only rs8050136 and rs9939609 were associated with BMI and WAIST (P values of 0.011 and 0.034), and associated or trending towards association with SAT (P values of 0.038 and 0.058). These results confirm that FTO variants are associated with adiposity measures, predisposing individuals to obesity by increasing overall fat mass in Hispanic Americans and to a lesser degree in African Americans.     

Variant allele of <Emphasis Type="Italic">CHEK2</Emphasis> is associated with a decreased risk of esophageal cancer lymph node metastasis in a Chinese population

Growing evidence suggests that the checkpoint kinase 2 (CHEK2) signaling pathway occupies a central position in the signaling networks of DNA-damage signaling. Many functional and molecular epidemiological studies have evaluated the association between genetic variants of CHEK2 and various cancers. To evaluate the relationship between CHEK2 functional genetic variants and esophageal cancer risk and the risk of lymph node metastasis among a Chinese population. We genotyped CHEK2 rs738722, rs2236141 and rs2236142 single nucleotide polymorphisms (SNPs) using the matrix assisted laser desorption/ionization time-of-flight mass spectrometry assay in a case–controlled study, including 380 esophageal cancer cases and 380 healthy controls in a Chinese population. We found that none of the three polymorphisms achieved significant difference in their distributions between esophageal cancer cases and controls. Multiple logistic regression analyses revealed that esophageal cancer risk was not associated significantly with the variant genotypes of the three CHEK2 polymorphisms as compared with their wild-type genotypes. However, we found that functional variant rs738722 and rs2236142 in CHEK2 might contribute to susceptibility to lymph node metastasis. Our data did not support a significant association between CHEK2 SNPs and the risk of esophageal cancer. Functional variant CHEK2 rs738722 and rs2236142 might contribute to lymph node metastasis susceptibility. The CT allele of SNP rs738722 and the GC allele of SNP rs2236142 might be a protective factor of the risk for lymph node metastasis of esophageal cancer.     

Association of CHI3L1 gene variants with YKL-40 levels and hypertension incidence: A population-based nested case-control study in China

YKL-40 was reported to be associated with the risk of hypertension. Whether the variants of CHI3L1 gene were associated with both YKL-40 levels and hypertension needs to be further elucidated. In a 1:1 matched case-control study of 507 pairs with available YKL-40 levels and DNA samples nested in a prospective cohort of Chinese subjects, the 15 tag single nucleotide polymorphisms (SNPs) of CHI3L1 gene were genotyped. The levels of YKL-40 among different genotypes of each SNP were compared after false discovery rate adjustment. Multivariable conditional logistic regression analyses were used to explore the association between the genotypes and the risk of hypertension. Subjects with the genetic variants for rs10399931, rs1538372, rs2071580, rs2297839 and rs4950928 had lower YKL-40 levels. The genetic variant for rs10399805 was associated with higher YKL-40 level. Subjects with the genotype of GA/AA of rs10399805 had a 1.34-fold risk of hypertension compared with those with GG genotype in the total population (P = .05). Subjects with heterozygote/rare homozygote genotype of rs4950928 and rs2297839 both had a significantly lower risk of hypertension compared with those with major homozygote genotype among men. The ORs (95% CIs) were 0.46 (0.23-0.89) and 0.49 (0.26-0.91), respectively. The above three SNPs could significantly improve the accuracy of risk prediction for hypertension based on the conventional factors. The genotypes of rs10399805, rs4950928 and rs2297839 may hopefully become stable biomarkers for predicting the risk of hypertension.     

Genetic variants in the mannose receptor gene (MRC1) are associated with asthma in two independent populations

Mannose receptor is a member of the C-type lectin receptor family involved in pathogen molecular pattern recognition and thought to be critical in shaping host immune responses and maintaining homeostasis. The aim of this study was to investigate potential associations of genetic variants in the MRC1 gene with asthma in two independent populations. Seven single-nucleotide polymorphisms (SNPs; rs2477637, rs2253120, rs2477631, rs2477664, rs692527, rs1926736, and rs691005) in the MRC1 gene locus were genotyped and evaluated regarding association with asthma in 870 unrelated Japanese subjects (446 asthmatics, 424 controls). The same markers were validated in 176 unrelated African–American subjects (86 asthmatics, 90 controls). Suggestive evidence of association between five SNPs (rs2477637, rs2253120, rs2477664, rs692527, and rs1926736) and asthma was observed in the analysis of the Japanese population independent of sex, age, smoking status, and atopic status. SNPs rs692527 and rs691005 showed significant association with asthma in the African–American population. Haplotypes containing two linked SNPs (rs692527 and rs1926736) were significantly associated with asthma in both Japanese and African–American populations. Our results suggest that sequence variations in the MRC1 gene are associated with the development of asthma in two independent and ethnically diverse populations.     

Interactions between Environmental Factors and Melatonin Receptor Type 1A Polymorphism in Relation to Oral Cancer Susceptibility and Clinicopathologic Development

Background

The purpose of this study was to explore the combined effect of melatonin receptor type 1A (MTNR1A) gene polymorphisms and exposure to environmental carcinogens on the susceptibility and clinicopathological characteristics of oral cancer.

Methodology and Principal Findings

Three polymorphisms of the MTNR1A gene from 618 patients with oral cancer and 560 non-cancer controls were analyzed by real-time polymerase chain reaction (PCR). The CTA haplotype of the studied MTNR1A polymorphisms (rs2119882, rs13140012, rs6553010) was related to a higher risk of oral cancer. Moreover, MTNR1A gene polymorphisms exhibited synergistic effects of environmental factors (betel quid and tobacco use) on the susceptibility of oral cancer. Finally, oral-cancer patients with betel quid-chewing habit who had T/T allele of MTNR1A rs13140012 were at higher risk for developing an advanced clinical stage and lymph node metastasis.

Conclusion

These results support gene-environment interactions of MTNR1A polymorphisms with smoking and betel quid-chewing habits possibly altering oral-cancer susceptibility and metastasis.