Plasma glutathione peroxidase in pediatric stroke families

Selenium, a Micronutrient That Modulates Cardiovascular Health via Redox Enzymology

Selenium (Se) is a trace nutrient that promotes human health through its incorporation into selenoproteins in the form of the redox-active amino acid selenocysteine (Sec). There are 25 selenoproteins in humans, and many of them play essential roles in the protection against oxidative stress. Selenoproteins, such as glutathione peroxidase and thioredoxin reductase, play an important role in the reduction of hydrogen and lipid hydroperoxides, and regulate the redox status of Cys in proteins. Emerging evidence suggests a role for endoplasmic reticulum selenoproteins, such as selenoproteins K, S, and T, in mediating redox homeostasis, protein modifications, and endoplasmic reticulum stress. Selenoprotein P, which functions as a carrier of Se to tissues, also participates in regulating cellular reactive oxygen species. Cellular reactive oxygen species are essential for regulating cell growth and proliferation, protein folding, and normal mitochondrial function, but their excess causes cell damage and mitochondrial dysfunction, and promotes inflammatory responses. Experimental evidence indicates a role for individual selenoproteins in cardiovascular diseases, primarily by modulating the damaging effects of reactive oxygen species. This review examines the roles that selenoproteins play in regulating vascular and cardiac function in health and disease, highlighting their antioxidant and redox actions in these processes.

Thrombophilia risk is not increased in children after perinatal stroke

Thrombophilia in children with perinatal stroke is rare, with rates similar to those in the normal population. Routine testing in childhood is not indicated.

Screening of the GPX3 gene identifies the "T" allele of the SNP -861A/T as a risk for ischemic stroke in young Asian Indians

BACKGROUND

Deficiency of plasma glutathione peroxidase (GPx-3) has been associated with platelet-dependent thrombosis. Single-nucleotide polymorphisms (SNPs) in the promoter region of GPX3 gene have been found associated with the risk for ischemic stroke in Caucasian populations. The aim of our present study was to evaluate the impact of genetic variations in the GPX3 gene and plasma GPx-3 antigen levels on ischemic stroke in young Asian Indians.

METHODS

One hundred patients with ischemic stroke and 200 age- and sex-matched controls were studied. Genetic analysis for the study population was done by a combination of variant screening using single-stranded conformation polymorphism and final genotyping by polymerase chain reaction-restriction fragment length polymorphism and allele-specific polymerase chain reactions. Plasma GPx-3 antigen levels were evaluated using commercial kits. Data were analyzed using genetic analysis software and statistical tools.

RESULTS

Significantly higher GPx-3 levels were observed in controls compared with patients (controls 26.37 ± 3.66 μg/mL and patients 22.83 ± 4.57 μg/mL, P < .001). Only the SNP -861A/T was found associated with stroke phenotype (P < .0001). The SNP -568T/C was observed to significantly influence plasma GPx-3 levels (P < .05). The haplotype carrying the risk "T" allele of SNP -861A/T was significantly over-represented in patients with stroke (P < .0001).

CONCLUSIONS

The T allele of -861A/T is a risk allele for the ischemic stroke phenotype. The -861A/T and -568T/C SNPs may show a statistically significant association with both plasma GPx-3 antigen levels and the stroke phenotype in a larger sample size.

Association of glutathione peroxidase-1 (GPx-1) rs1050450 Pro198Leu and Pro197Leu polymorphisms with cardiovascular risk: a meta-analysis of observational studies

Objective

To clarify the association between rs1050450 polymorphism in Glutathione peroxidase-1 (GPx-1) and the risk of cardiovascular diseases (CVD) by performing a meta-analysis of published studies. There is growing evidence from different study types for an association of the GPx-1 polymorphism and cardiovascular outcomes, but observational studies have so far shown inconsistent results.

Methods

Relevant publications were searched through PubMed, Embase database databases and the Cochrane Library. We used odds ratios (ORs) with 95% confidence intervals (CIs) to assess the strength of association under the best genetic model. Both Q statistic and the I² were used to check heterogeneity. Meta-regression analysis was performed to explore heterogeneity source. Sensitivity analysis, cumulative meta-analysis analysis and publication bias were used to test the reliability of the results.

Results

Data were available from two cohort studies and 8 case-control studies involving 1,430 cases and 3,767 controls. The pooled ORs for overall CVD risk was 1.36 with 95% CI: 1.08–1.70 under a co-dominant model, and that for East Asian subgroup was 1.84 (95% CI: 1.39–2.43). Substantial heterogeneity for ORs were detected among all the included studies, mainly caused by ethnic differences between East Asian and non-East Asian populations. Although Egger's regression test suggested no statistical significant publication bias, Begg's funnel plot exhibited obvious asymmetry. The statistical significance disappeared after adjusting for potential publication bias in the overall studies. However, no substantial publication bias was found in the East Asian subgroup.

Conclusions

GPx-1 gene Pro198Leu and Pro197Leu polymorphisms considerably increased the risk of CVD in the East Asian population. Large-scale investigations are needed to confirm the results in different ethnicities.

Advances in understanding stroke risk in children--a geneticist's view

The advent of the genomic era has provided novel insights into the genetic architecture of common complex diseases, such as thrombophilia and stroke. Since 2006, a growing number of genome wide association studies (GWAS) for common complex diseases have revealed new candidate loci and genomic regions that play an important role in disease aetiology and progression. While GWAS on the above mentioned traits are abundant in adults, similar studies in paediatric study cohorts are lagging behind. However, genetic research in this important clinical area has gained momentum and starts to provide us with exciting insights into the genetic underpinnings of stroke with paediatric onset. Here we review recent advances in genetic association studies underlying stroke in children and aim to translate the results to clinical utility. These studies comprise candidate gene approaches and GWAS, and represent the current status on what we have learnt about the genetic architecture underlying paediatric stroke, and how this may affect medical practice in the years to come.

Functional diversity of the glutathione peroxidase gene family among human populations: implications for genetic predisposition to disease and drug response

Aim: To analyze the human genetic variation of glutathione peroxidases (GPX), estimating the functional differences among human populations and suggesting interethnic differences in predisposition to disease and drug response. Materials & methods: Using 1000 Genomes Project data, we analyzed 723 GPX variants in 1092 individuals belonging to 14 populations. Combining functional prediction analyses of coding and noncoding variants, we developed a method to estimate haplotype functionality. Results: GPX rare variants have a higher functional impact than common variants. The frequency among Asian patients of haplotypes associated with normal functionality is significantly higher for GPX1 and lower for GPX3 than for non-Asian patients; no adaptation signals in GPX1 and GPX3 were found in Asian patients. Conclusion: GPX1 and GPX3 differences may be associated with alterations in antioxidant capacity and redox regulation, which suggests diverse susceptibility to complex disease and diverse response to relevant drugs in Asians compared with individuals with other ethnic origins.

Original submitted 7 February 2013; Revision submitted 16 May 2013

The C718T polymorphism in the 3'-untranslated region of glutathione peroxidase-4 gene is a predictor of cerebral stroke in patients with essential hypertension

In the present study we have investigated the association of three single nucleotide polymorphisms in glutathione peroxidase (GPx) genes GPX1 rs1050450 (P198L), GPX3 rs2070593 (G930A) and GPX4 rs713041 (T718C) with the risk of cerebral stroke (CS) in patients with essential hypertension (EH). A total of 667 unrelated EH patients of Russian origin, including 306 hypertensives (the EH-CS group) who suffered from CS and 361 people (the EH-CS group) who did not have cerebrovascular accidents, were enrolled in the study. The variant allele 718C of the GPX4 gene was found to be significantly associated with an increased risk of CS in hypertensive patients (odds ratio (OR) 1.53, 95% confidence interval (CI) 1.23-1.90, P(adj) = 0.0003). The prevalence of the 718TC and 718CC genotypes of the GPX4 gene was higher in the EH-CS group than the EH-alone group (OR = 2.12, 95%CI 1.42-3.16, P(adj) = 0.0018). The association of the variant GPX4 genotypes with the increased risk of CS in hypertensives remained statistically significant after adjusting for confounding variables such as sex, body mass index (BMI), blood pressure and antihypertensive medication use (OR = 2.18, 95%CI 1.46-3.27, P = 0.0015). Multiple logistic regression analysis did not reveal any interaction between various combinations of GPX1, GPX3 and GPX4 genotypes regarding the risk of CS in patients with EH. The study demonstrated for the first time that the C718T polymorphism in the 3'-untranslated region of the GPX4 gene could be considered as a genetic marker of susceptibility to CS in patients with EH.