Change in DNA Methylation Patterns of SLC6A4 Gene in the Gastric Mucosa in Functional Dyspepsia

Background

The neurochemical serotonin (5-HT) is an important signaling molecule in the gastrointestinal motor and sensory functions. A key regulator of 5-HT levels is the transmembrane serotonin transporter (5-HTT; SLC6A4) that governs the reuptake of 5-HT. Recent studies have indicated 5-HTT expression may be regulated by epigenetic mechanisms. We investigated DNA methylation status of SLC6A4 gene in the gastric mucosa from functional dyspepsia (FD) because of their potential role in dyspeptic symptoms.

Methods

Endoscopic gastric biopsies were obtained from 78 subjects with no upper abdominal symptoms and 79 patients with FD. Bisulfite Pyrosequencing was carried out to determine the methylation status of promoter CpG islands (PCGIs), promoter non-CpG islands (PNCGIs) and gene body non-CpG islands (NPNCGIs) in the SLC6A4 gene. Gene expression was examined by real-time PCR.

Results

In overall, methylation level of PCGIs was significantly lower in FD compared to control subjects (p = 0.04). On the other hand, methylation level of NPNCGIs was significantly higher in FD compared to control subjects (p = 0.03). Lower methylation level in PNCGIs was highlighted in the patients with PDS (p = 0.01), while higher methylation level in NPNCGIs was more prominent in the patients with EPS (p = 0.017). Methylation levels of PCGIs and PNCGIs were inversely correlated, while methylation levels of NPNCGIs was positively correlated with SLC6A4 mRNA levels in FD patients.

Conclusions

Our data suggest that change in DNA methylation pattern of SLC6A4 in the gastric mucosa may have a role for developing FD. A role of epigenetics for developing FD needs to be further evaluated.     

Prenatal Exposure to Maternal Depressed Mood and the MTHFR C677T Variant Affect SLC6A4 Methylation in Infants at Birth

Background

Prenatal and early postnatal exposure to maternal depression may “program” childhood behavior via epigenetic processes such as DNA methylation. Methylenetetrahydro-folate reductase (MTHFR) is an important enzyme in the generation of methyl groups for DNA methylation. The common MTHFR C677T variant is associated with depression in men and non-pregnant women, and with global changes in DNA methylation. This study investigated the effect of maternal MTHFR C677T genotype on antenatal maternal mood, and their impact on the gene-specific methylation in pregnant women and their newborn infants. The methylation status of SLC6A4, which encodes the transmembrane serotonin transporter, and BDNF, which encodes brain derived neurotrophic factor, were assessed because of their potential role in behaviour.

Methods/Principal Findings

Depressed mood was assessed by the Edinburgh Postnatal Depression Scale (EPDS) and the Hamilton Rating Scale for Depression (HAM-D) in women (n = 82, all taking folate) during the 2^nd and 3^rd trimesters of pregnancy. The methylation status of SLC6A4 and BDNF were assessed in 3rd trimester maternal peripheral leukocytes and in umbilical cord leukocytes collected from their infants at birth. Women with the MTHFR 677TT genotype had greater 2^nd trimester depressed mood (p<0.05). Increased 2^nd trimester maternal depressed mood (EPDS scores) was associated with decreased maternal and infant SLC6A4 promoter methylation (p<0.05), but had no effect on BDNF promoter methylation.

Conclusions

These findings show that the MTHFR C677T variant is associated with greater depressed mood during pregnancy. We further showed that prenatal exposure to maternal depressed mood affects gene-specific DNA methylation patterns. These findings support the concept that alterations in epigenetic processes may contribute to developmental programming of behaviour by maternal depression.     

Aberrant Gene Promoter Methylation Associated with Sporadic Multiple Colorectal Cancer

Background

Colorectal cancer (CRC) multiplicity has been mainly related to polyposis and non-polyposis hereditary syndromes. In sporadic CRC, aberrant gene promoter methylation has been shown to play a key role in carcinogenesis, although little is known about its involvement in multiplicity. To assess the effect of methylation in tumor multiplicity in sporadic CRC, hypermethylation of key tumor suppressor genes was evaluated in patients with both multiple and solitary tumors, as a proof-of-concept of an underlying epigenetic defect.

Methodology/Principal Findings

We examined a total of 47 synchronous/metachronous primary CRC from 41 patients, and 41 gender, age (5-year intervals) and tumor location-paired patients with solitary tumors. Exclusion criteria were polyposis syndromes, Lynch syndrome and inflammatory bowel disease. DNA methylation at the promoter region of the MGMT, CDKN2A, SFRP1, TMEFF2, HS3ST2 (3OST2), RASSF1A and GATA4 genes was evaluated by quantitative methylation specific PCR in both tumor and corresponding normal appearing colorectal mucosa samples. Overall, patients with multiple lesions exhibited a higher degree of methylation in tumor samples than those with solitary tumors regarding all evaluated genes. After adjusting for age and gender, binomial logistic regression analysis identified methylation of MGMT2 (OR, 1.48; 95% CI, 1.10 to 1.97; p = 0.008) and RASSF1A (OR, 2.04; 95% CI, 1.01 to 4.13; p = 0.047) as variables independently associated with tumor multiplicity, being the risk related to methylation of any of these two genes 4.57 (95% CI, 1.53 to 13.61; p = 0.006). Moreover, in six patients in whom both tumors were available, we found a correlation in the methylation levels of MGMT2 (r = 0.64, p = 0.17), SFRP1 (r = 0.83, 0.06), HPP1 (r = 0.64, p = 0.17), 3OST2 (r = 0.83, p = 0.06) and GATA4 (r = 0.6, p = 0.24). Methylation in normal appearing colorectal mucosa from patients with multiple and solitary CRC showed no relevant difference in any evaluated gene.

Conclusions

These results provide a proof-of-concept that gene promoter methylation is associated with tumor multiplicity. This underlying epigenetic defect may have noteworthy implications in the prevention of patients with sporadic CRC.     

DNA Methyltransferase Candidate Polymorphisms,Imprinting Methylation,and Birth Outcome

Background

Birth weight and prematurity are important obstetric outcomes linked to lifelong health. We studied a large birth cohort to look for evidence of epigenetic involvement in birth outcomes.

Methods

We investigated the association between birth weight, length, placental weight and duration of gestation and four candidate variants in 1,236 mothers and 1,073 newborns; DNMT1 (rs2162560), DNMT3A (rs734693), DNMT3B (rs2424913) and DNMT3L (rs7354779). We measured methylation of LINE1 and the imprinted genes, PEG3, SNRPN, and IGF2, in cord blood.

Results

The minor DNMT3L allele in the baby was associated with higher birth weight (+54 95% CI 10,99 g; p = 0.016), birth length (+0.23 95% CI 0.04,0.42 cm; p = 0.017), placental weight, (+18 95% CI 3,33 g; p = 0.017), and reduced risk of being in the lowest birth weight decile (p = 0.018) or requiring neonatal care (p = 0.039). The DNMT3B minor allele in the mother was associated with an increased risk of prematurity (p = 0.001). Placental size was related to PEG3 (p<0.001) and IGF2 (p<0.001) methylation. Birth weight was related to LINE1 and IGF2 methylation but only at p = 0.052. The risk of requiring neonatal treatment was related to LINE1 (p = 0.010) and SNRPN (p = 0.001) methylation. PEG3 methylation was influenced by baby DNMT3A genotype (p = 0.012) and LINE1 by baby 3B genotype (p = 0.044). Maternal DNMT3L genotype was related to IGF2 methylation in the cord blood but this effect was only seen in carriers of the minor frequency allele (p = 0.050).

Conclusions

The results here suggest that epigenetic processes are linked birth outcome and health in early life. Our emerging understanding of the role of epigenetics in health and biological function across the lifecourse suggests that these early epigenetic events could have longer term implications.     

Hypermethylation of Genes Detected in Urine from Ghanaian Adults with Bladder Pathology Associated with Schistosoma haematobium Infection

Purpose

Schistosoma haematobium is associated with chronic bladder damage and may subsequently induce bladder cancer in humans, thus posing a serious threat where the parasite is endemic. Here we evaluated aberrant promoter DNA methylation as a potential biomarker to detect severe bladder damage that is associated with schistosomiasis by analyzing urine specimens.

Materials and Methods

A quantitative methylation-specific PCR (QMSP) assay was used to examine the methylation status of seven genes (RASSF1A, RARβ2, RUNX3, TIMP3, MGMT, P16, ARF) in 57 urine samples obtained from volunteers that include infected and uninfected by S. haematobium from an endemic region. The Fishers Exact Test and Logistic Regression analysis were used to evaluate the methylation status with bladder damage (as assessed by ultrasound examination) in subjects with S. haematobium infection.

Results

RASSF1A and TIMP3 were significant to predict severe bladder damage both in univariate (p = 0.015 and 0.023 respectively) and in multivariate (p = 0.022 and 0.032 respectively) logistic regression analysis. Area under the receiver operator characteristic curves (AUC-ROC) for RASSF1A and TIMP3 to predict severe bladder damage were 67.84% and 63.73% respectively. The combined model, which used both RASSF1A and TIMP3 promoter methylation, resulted in significant increase in AUC-ROC compared to that of TIMP3 (77.55% vs. 63.73%.29; p = 0.023).

Conclusions

In this pilot study, we showed that aberrant promoter methylation of RASSF1A and TIMP3 are present in urine sediments of patients with severe bladder damage associated with S. haematobium infection and that may be used to develop non-invasive biomarker of S. haematobium exposure and early molecular risk assessmentof neoplastic transformation.     

A High Degree of LINE-1 Hypomethylation Is a Unique Feature of Early-Onset Colorectal Cancer

Objective

Early-onset colorectal cancer (CRC) represents a clinically distinct form of CRC that is often associated with a poor prognosis. Methylation levels of genomic repeats such as LINE-1 elements have been recognized as independent factors for increased cancer-related mortality. The methylation status of LINE-1 elements in early-onset CRC has not been analyzed previously.

Design

We analyzed 343 CRC tissues and 32 normal colonic mucosa samples, including 2 independent cohorts of CRC diagnosed ≤50 years old (n = 188), a group of sporadic CRC >50 years (MSS n = 89; MSI n = 46), and a group of Lynch syndrome CRCs (n = 20). Tumor mismatch repair protein expression, microsatellite instability status, LINE-1 and MLH1 methylation, somatic BRAF V600E mutation, and germline MUTYH mutations were evaluated.

Results

Mean LINE-1 methylation levels (±SD) in the five study groups were early-onset CRC, 56.6% (8.6); sporadic MSI, 67.1% (5.5); sporadic MSS, 65.1% (6.3); Lynch syndrome, 66.3% (4.5) and normal mucosa, 76.5% (1.5). Early-onset CRC had significantly lower LINE-1 methylation than any other group (p<0.0001). Compared to patients with <65% LINE-1 methylation in tumors, those with ≥65% LINE-1 methylation had significantly better overall survival (p = 0.026, log rank test).

Conclusions

LINE-1 hypomethylation constitutes a potentially important feature of early-onset CRC, and suggests a distinct molecular subtype. Further studies are needed to assess the potential of LINE-1 methylation status as a prognostic biomarker for young people with CRC.     

A Meta-Analysis of the Effects of the 5-Hydroxytryptamine Transporter Gene-Linked Promoter Region Polymorphism on Susceptibility to Lifelong Premature Ejaculation

Objective

Premature ejaculation (PE) has been reported as the most common male sexual dysfunction with global prevalence rates estimated at approximately 30%. The neurobiogenesis of ejaculation is very complex and involves the serotoninergic (5-hydroxytryptamine, 5-HT) system. Recently, genetic polymorphisms located on SLC6A4 gene codifying for 5-HT transporter (5-HTT), the major regulator of serotonic neurotransmission, have been linked with the pathogenesis and risk of PE. Apparently studies of this type of polymorphism in PE have show conflicting results.

Methods

A meta-analysis was performed that are available in relation with 5-HTT gene-linked promoter region (5-HTTLPR) polymorphism and the risk of lifelong PE (LPE) in men to clarify this relationship. We searched Pubmed and Embase (last search updated on Aug 2012) using ‘premature ejaculation’, ‘polymorphism or variant’, ‘genotype’, ‘ejaculatory function’, and ‘rapid ejaculation’ as keywords and reference lists of studies corresponded to the inclusion criteria for meta-analysis. These studies involved the total number of 481 LPE men and 466 health control men subjects. Odds ratio (OR) and 95% confidence intervals (CIs) were used to evaluate this relationship.

Results

In the overall analysis, significant associations between LPE risk and 5-HTTLPR polymorphism were found (L-allele vs. S-allele OR = 0.86, 95% CI = 0.79–0.95, P = 0.002; LL vs. SS: OR = 0.80, 95% CI = 0.68–0.95, P = 0.009; LS vs. SS: OR = 0.85, 95% CI = 0.76–0.97, P = 0.012 and LL+LS vs. SS: OR = 0.88, 95% CI = 0.81–0.95, P = 0.002). Moreover, in subgroup analysis based on ethnicity, similar significant associations were detected. The Egger’s test did not reveal presence of a publication bias.

Conclusions

Our investigations demonstrate that 5-HTTLPR (L>S) polymorphism might protect men against LPE risk. Further studies based on larger sample size and gene-environment interactions should be conducted the role of 5-HTTLPR polymorphism and LPE risk.     

The Associations of Serum Serotonin with Bone Traits Are Age- and Gender-Specific

Context

Serotonin plays a potential role in bone metabolism, but the nature and extent of this relationship is unclear and human studies directly addressing the skeletal effect of circulating serotonin are rare.

Objective

The study aimed to investigate the associations between serum serotonin and bone traits at multiple skeletal sites in women and men.

Subjects and Methods

Subjects were part of the CALEX-family study and comprised 235 young women, 121 premenopausal women, 124 postmenopausal women, and 168 men. Body composition was assessed using DXA, as was areal bone mineral density (aBMD) of spine, femur and whole body. In addition, pQCT was used to determine bone properties at tibial midshaft and distal radius. Fasting serum serotonin concentration was assessed using a competitive enzyme-linked immunosorbent assay.

Results

Serum serotonin declined with advancing age both in females and males (all p<0.01). Serotonin was negatively correlated with weight, BMI, lean and fat mass in women (r = −0.22 to −0.39, all p<0.001), but positively with height and lean mass in men (all p<0.01). In the premenopausal women, serotonin was negatively correlated with lumbar spine aBMD (r = −0.23, p<0.05) but the statistical significance disappeared after adjustment for weight. Conversely, in postmenopausal women, serotonin was positively correlated with whole body and femur aBMD, as well as with distal radius bone mineral content and volumetric BMD (r = 0.20 to 0.30, all p<0.05), and these associations remained significant after adjustment for weight. In men, no significant associations were found between serotonin and bone traits.

Conclusion

Serum serotonin is positively associated with bone traits in postmenopausal women, but not in premenopausal women or men. This partially supports the idea of circulating serotonin playing a role in the regulation of bone metabolism, but also indicates the importance of gender and age specific factors.     

Association between DAPK1 Promoter Methylation and Cervical Cancer: A Meta-Analysis

Background

Death-associated protein kinase1 (DAPK1) is an important tumor suppressor gene. DNA methylation can inactivate genes, which has often been observed in the carcinogenesis of cervical cancer. During the past several decades, many studies have explored the association between DAPK1 promoter methylation and cervical cancer. However, many studies were limited by the small samples size and the findings were inconsistent among them. Thus, we conducted a meta-analysis to assess the association between DAPK1 promoter methylation and cervical cancer.

Methods

We systematically searched eligible studies in the PubMed, Web of Science, EMBASE and CNKI databases. Using meta-regression, subgroup analysis and sensitivity analysis, we explored the potential sources of heterogeneity. The odds ratio (OR) and 95% confidence interval (95% CI) were calculated by Meta-Analysis in R.

Results

A total of 15 studies from 2001 to 2012, comprising 818 tumor tissues samples and 671 normal tissues samples, were analyzed in this meta-analysis. The frequencies of DAPK1 promoter methylation ranged from 30.0% to 78.6% (median, 59.3%) in cervical cancer tissue and 0.0% to 46.7% (median, 7.8%) in normal cervical tissue. The pooled OR was 19.66 (95%CI = 8.72–44.31) with the random effects model, and heterogeneity was found through the sensitivity analysis. The I² = 60% (P = 0.002) decreased to I² = 29.2% (P = 0.144) when one heterogeneous study was excluded, and the pooled OR increased to 21.80 (95%CI = 13.44–35.36) with the fixed effects model.

Conclusion

The results suggested a strong association between DAPK1 promoter methylation and cervical cancer. This study also indicated that DAPK1 promoter methylation may be a biomarker during cervical carcinogenesis that might serve as an early indication of cervical cancer.     

IGFBP3 Methylation Is a Novel Diagnostic and Predictive Biomarker in Colorectal Cancer

Background and Aim

Aberrant hypermethylation of cancer-related genes has emerged as a promising strategy for the development of diagnostic, prognostic and predictive biomarkers in human cancer, including colorectal cancer (CRC). The aim of this study was to perform a systematic and comprehensive analysis of a panel of CRC-specific genes as potential diagnostic, prognostic and predictive biomarkers in a large, population-based CRC cohort.

Patients and Methods

Methylation status of the SEPT9, TWIST1, IGFBP3, GAS7, ALX4 and miR137 genes was studied by quantitative bisulfite pyrosequencing in a population-based cohort of 425 CRC patients.

Results

Methylation levels of all genes analyzed were significantly higher in tumor tissues compared to normal mucosa (p<0.0001); however, cancer-associated hypermethylation was most frequently observed for miR137 (86.7%) and IGFBP3 (83%) in CRC patients. Methylation analysis using the combination of these two genes demonstrated greatest accuracy for the identification of colonic tumors (sensitivity 95.5%; specificity 90.5%). Low levels of IGFBP3 promoter methylation emerged as an independent risk factor for predicting poor disease free survival in stage II and III CRC patients (HR = 0.49, 95% CI: 0.28–0.85, p = 0.01). Our results also suggest that stage II & III CRC patients with high levels of IGFBP3 methylation do not benefit from adjuvant 5FU-based chemotherapy.

Conclusion

By analyzing a large, population-based CRC cohort, we demonstrate the potential clinical significance of miR137 and IGFBP3 hypermethylation as promising diagnostic biomarkers in CRC. Our data also revealed that IGFBP3 hypermethylation may serve as an independent prognostic and predictive biomarker in stage II and III CRC patients.     

Potential of Ayurgenomics Approach in Complex Trait Research: Leads from a Pilot Study on Rheumatoid Arthritis

Background

Inconsistent results across association studies including Genome-wide association, have posed a major challenge in complex disease genetics. Of the several factors which contribute to this, phenotypic heterogeneity is a serious limitation encountered in modern medicine. On the other hand, Ayurveda, a holistic Indian traditional system of medicine, enables subgrouping of individuals into three major categories namely Vata, Pitta and Kapha, based on their physical and mental constitution, referred to as Prakriti. We hypothesised that conditioning association studies on prior risk, predictable in Ayurveda, will uncover much more variance and potentially open up more predictive health.

Objectives and Methods

Identification of genetic susceptibility markers by combining the prakriti based subgrouping of individuals with genetic analysis tools was attempted in a Rheumatoid arthritis (RA) cohort. Association of 21 markers from commonly implicated inflammatory and oxidative stress pathways was tested using a case-control approach in a total cohort comprising 325 cases and 356 controls and in the three subgroups separately. We also tested few postulates of Ayurveda on the disease characteristics in different prakriti groups using clinico-genetic data.

Results

Inflammatory genes like IL1β (C-C-C haplotype, p = 0.0005, OR = 3.09) and CD40 (rs4810485 allelic, p = 0.04, OR = 2.27) seem to be the determinants in Vata subgroup whereas oxidative stress pathway genes are observed in Pitta (SOD3 rs699473, p = 0.004, OR = 1.83; rs2536512 p = 0.005; OR = 1.88 and PON1 rs662, p = 0.04, OR = 1.53) and Kapha (SOD3 rs2536512, genotypic, p = 0.02, OR = 2.39) subgroups. Fixed effect analysis of the associated markers from CD40, SOD3 and TNFα with genotype X prakriti interaction terms suggests heterogeneity of effects within the subgroups. Further, disease characteristics such as severity was most pronounced in Vata group.

Conclusions

This exploratory study suggests discrete causal pathways for RA etiology in prakriti based subgroups, thereby, validating concepts of prakriti and personalized medicine in Ayurveda. Ayurgenomics approach holds promise for biomarker discovery in complex diseases.     

Methylation of p15INK4b and Expression of ANRIL on Chromosome 9p21 Are Associated with Coronary Artery Disease

Background

Genome-wide association studies have identified that multiple single nucleiotide polymorphisms on chromosome 9p21 are tightly associated with coronary artery disease (CAD). However, the mechanism linking this risk locus to CAD remains unclear.

Methodology/Principal Findings

The methylation status of six candidate genes (BAX, BCL-2, TIMP3, p14^ARF, p15^INK4b and p16^INK4a) in 205 patients and controls who underwent coronary angiography were analyzed by quantitative MethyLight assay. Rs10757274 was genotyped and expression of INK4/ARF and antisense non-coding RNA in the INK4 locus (ANRIL) was determined by real-time RT-PCR. Compared with controls, DNA methylation levels at p15^INK4b significantly increased in CAD patients (p = 0.006). To validate and dissect the methylation percentage of each target CpG site at p15^INK4b, pyrosequencing was performed, finding CpG +314 and +332 remarkably hypermethylated in CAD patients. Further investigation determined that p15^INK4b hypermethylation prevalently emerged in lymphocytes of CAD patients (p = 0.013). The rs10757274 genotype was significantly associated with CAD (p = 0.003) and GG genotype carriers had a higher level of ANRIL exon 1–5 expression compared among three genotypes (p = 0.009). There was a stepwise increase in p15^INK4b and p16^INK4a methylation as ANRIL exon 1–5 expression elevated (r = 0.23, p = 0.001 and r = 0.24, p = 0.001, respectively), although neither of two loci methylation was directly linked to rs10757274 genotype.

Conclusions/Significance

p15^INK4b methylation is associated with CAD and ANRIL expression. The epigenetic changes in p15^INK4b methylation and ANRIL expression may involve in the mechanisms of chromosome 9p21 on CAD development.     

MLH1 Promoter Methylation Frequency in Colorectal Cancer Patients and Related Clinicopathological and Molecular Features

Purpose

To describe the frequency of MLH1 promoter methylation in colorectal cancer (CRC); to explore the associations between MLH1 promoter methylation and clinicopathological and molecular factors using a systematic review and meta-analysis.

Methods

A literature search of the PubMed and Embase databases was conducted to identify relevant articles published up to September 7, 2012 that described the frequency of MLH1 promoter methylation or its associations with clinicopathological and molecular factors in CRC. The pooled frequency, odds ratio (OR) and 95% confidence intervals (95% CI) were calculated.

Results

The pooled frequency of MLH1 promoter methylation in unselected CRC was 20.3% (95% CI: 16.8–24.1%). They were 18.7% (95% CI: 14.7–23.6%) and 16.4% (95% CI: 11.9–22.0%) in sporadic and Lynch syndrome (LS) CRC, respectively. Significant associations were observed between MLH1 promoter methylation and gender (pooled OR = 1.641, 95% CI: 1.215–2.215; P = 0.001), tumor location (pooled OR = 3.804, 95% CI: 2.715–5.329; P<0.001), tumor differentiation (pooled OR = 2.131, 95% CI: 1.464–3.102; P<0.001), MSI (OR: 27.096, 95% CI: 13.717–53.526; P<0.001). Significant associations were also observed between MLH1 promoter methylation and MLH1 protein expression, BRAF mutation (OR = 14.919 (95% CI: 6.427–34.631; P<0.001) and 9.419 (95% CI: 2.613–33.953; P = 0.001), respectively).

Conclusion

The frequency of MLH1 promoter methylation in unselected CRC was 20.3%. They were 18.7% in sporadic CRC and 16.4% in LS CRC, respectively. MLH1 promoter methylation may be significantly associated with gender, tumor location, tumor differentiation, MSI, MLH1 protein expression, and BRAF mutation.     

A Genome-Wide Methylation Study on Essential Hypertension in Young African American Males

Objective

There is emerging evidence from animal studies suggesting a key role for methylation in the pathogenesis of essential hypertension. However, to date, very few studies have investigated the role of methylation in the development of human hypertension, and none has taken a genome-wide approach. Based on the recent studies that highlight the involvement of inflammation in the development of hypertension, we hypothesize that changes in DNA methylation of leukocytes are involved in the pathogenesis of hypertension.

Method & Results

We conducted a genome-wide methylation analysis on 8 hypertensive cases and 8 normotensive age-matched controls aged 14–23 years and performed validation of the most significant CpG sites in 2 genes in an independent sample of 36 hypertensive cases and 60 normotensive controls aged 14–30 years. Validation of the CpG sites in the SULF1 gene was further conducted in a second replication sample of 36 hypertensive cases and 34 controls aged 15.8–40 years. A CpG site in the SULF1 gene showed higher methylation levels in cases than in healthy controls in the genome-wide step (p = 6.2×10⁻⁵), which was confirmed in the validation step (p = 0.011) for subjects ≤30 years old but was not significant for subjects of all ages combined (p = 0.095).

Conclusion

The identification of a difference in a blood leukocyte DNA methylation site between hypertensive cases and normotensive controls suggests that changes in DNA methylation may play an important role in the pathogenesis of hypertension. The age dependency of the effect further suggests complexity of epigenetic regulation in this age-related disease.     

Periconceptional Maternal Folic Acid Use of 400 μg per Day Is Related to Increased Methylation of the IGF2 Gene in the Very Young Child

Background

Countries worldwide recommend women planning pregnancy to use daily 400 µg of synthetic folic acid in the periconceptional period to prevent birth defects in children. The underlying mechanisms of this preventive effect are not clear, however, epigenetic modulation of growth processes by folic acid is hypothesized. Here, we investigated whether periconceptional maternal folic acid use and markers of global DNA methylation potential (S-adenosylmethionine and S-adenosylhomocysteine blood levels) in mothers and children affect methylation of the insulin-like growth factor 2 gene differentially methylation region (IGF2 DMR) in the child. Moreover, we tested whether the methylation of the IGF2 DMR was independently associated with birth weight.

Methodology/Principal Findings

IGF2 DMR methylation in 120 children aged 17 months (SD 0.3) of whom 86 mothers had used and 34 had not used folic acid periconceptionally were studied. Methylation was measured of 5 CpG dinucleotides covering the DMR using a mass spectrometry-based method. Children of mother who used folic acid had a 4.5% higher methylation of the IGF2 DMR than children who were not exposed to folic acid (49.5% vs. 47.4%; p = 0.014). IGF2 DMR methylation of the children also was associated with the S-adenosylmethionine blood level of the mother but not of the child (+1.7% methylation per SD S-adenosylmethionine; p = 0.037). Finally, we observed an inverse independent association between IGF2 DMR methylation and birth weight (−1.7% methylation per SD birthweight; p = 0.034).

Conclusions

Periconceptional folic acid use is associated with epigenetic changes in IGF2 in the child that may affect intrauterine programming of growth and development with consequences for health and disease throughout life. These results indicate plasticity of IGF2 methylation by periconceptional folic acid use.     

GTP Cyclohydrolase I Gene Polymorphisms Are Associated with Endothelial Dysfunction and Oxidative Stress in Patients with Type 2 Diabetes Mellitus

Background

The genetic background of atherosclerosis in type 2 diabetes mellitus (T2DM) is complex and poorly understood. Studying genetic components of intermediate phenotypes, such as endothelial dysfunction and oxidative stress, may aid in identifying novel genetic components for atherosclerosis in diabetic patients.

Methods

Five polymorphisms forming two haplotype blocks within the GTP cyclohydrolase 1 gene, encoding a rate limiting enzyme in tetrahydrobiopterin synthesis, were studied in the context of flow and nitroglycerin mediated dilation (FMD and NMD), intima-media thickness (IMT), and plasma concentrations of von Willebrand factor (vWF) and malondialdehyde (MDA).

Results

Rs841 was associated with FMD (p = 0.01), while polymorphisms Rs10483639, Rs841, Rs3783641 (which form a single haplotype) were associated with both MDA (p = 0.012, p = 0.0015 and p = 0.003, respectively) and vWF concentrations (p = 0.016, p = 0.03 and p = 0.045, respectively). In addition, polymorphism Rs8007267 was also associated with MDA (p = 0.006). Haplotype analysis confirmed the association of both haplotypes with studied variables.

Conclusions

Genetic variation of the GCH1 gene is associated with endothelial dysfunction and oxidative stress in T2DM patients.