Association of gene polymorphism with genetic susceptibility to stroke in Asian populations: a meta-analysis

Targeting Homocysteine and Hydrogen Sulfide Balance as Future Therapeutics in Cancer Treatment

A high level of homocysteine (Hcy) is associated with oxidative/ER stress, apoptosis, and impairment of angiogenesis, whereas hydrogen sulfide (H2S) has been found to reverse this condition. Recent studies have shown that cancer cells need to produce a high level of endogenous H2S to maintain cell proliferation, growth, viability, and migration. However, any novel mechanism that targets this balance of Hcy and H2S production has yet to be discovered or exploited. Cells require homocysteine metabolism via the methionine cycle for nucleotide synthesis, methylation, and reductive metabolism, and this pathway supports the high proliferative rate of cancer cells. Although the methionine cycle favors cancer cells for their survival and growth, this metabolism produces a massive amount of toxic Hcy that somehow cancer cells handle very well. Recently, research showed specific pathways important for balancing the antioxidative defense through H2S production in cancer cells. This review discusses the relationship between Hcy metabolism and the antiapoptotic, antioxidative, anti-inflammatory, and angiogenic effects of H2S in different cancer types. It also summarizes the historical understanding of targeting antioxidative defense systems, angiogenesis, and other protective mechanisms of cancer cells and the role of H2S production in the genesis, progression, and metastasis of cancer. This review defines a nexus of diet and precision medicine in targeting the delicate antioxidative system of cancer and explores possible future therapeutics that could exploit the Hcy and H2S balance.

Apolipoprotein E Gene Polymorphism Effects on Lipid Metabolism and Risk of Cerebral Infarction in Northwest Han Chinese Population

Background

The apolipoprotein E (ApoE) genetic variation may contribute to the development of Cerebral Infarction (CI). Serum lipid levels are known risk factors for CI, but the effect of the ApoE gene polymorphism on lipid metabolism remains unclear. This retrospective cohort study was designed to determine the role of ApoE genotypes in CI risk and the relationships between ApoE gene polymorphism and serum lipid levels among the population of northwest China.

Patients and Methods

517 CI patients and 517 non-CI controls were enrolled in the study. Polymerase chain reaction and hybridization were utilized to determine the ApoE gene polymorphisms.

Results

The ε3/ε4 genotype and ε4 allele frequency were significantly higher in CI patients than in controls. When stratified by age and sex, statistically significant differences in the distribution and frequency of the ε3/ε4 genotype and ε4 allele were found between patients and controls. Compared to ε2 carriers, ε4 carriers had significantly lower ApoE levels and higher low-density lipoprotein cholesterol (LDL-C), ApoB and ApoB/ApoA-I levels in both two groups. Additionally, control participants with ε4 carriers had significantly higher levels of lipoprotein and total cholesterol (TC) levels than ε2 carriers, while CI patients with ε4 carriers had a significantly lower level of ApoA-I. After adjusting for other established risk factors, drinking, hypertension, lipoprotein, triglycerides (TG) and ε4 allele were significant independent risk factors for CI, which was shown to be associated with a nearly two-fold CI risk.

Conclusion

This study demonstrated that ε4 allele is independent risk factors for CI among patients in Northwest China. ApoE polymorphism was associated with CI, which was partly mediated through blood lipids and may also be mediated through non-lipid pathways. These data might be of great clinical significance in individualized preventive and therapeutic strategies.

Transmembrane protease serine 2 (TMPRSS2) rs75603675, comorbidity, and sex are the primary predictors of COVID-19 severity

By the end of December 2021, coronavirus disease 2019 (COVID-19) produced more than 271 million cases and 5.3 million deaths. Although vaccination is an effective strategy for pandemic control, it is not yet equally available in all countries. Therefore, identification of prognostic biomarkers remains crucial to manage COVID-19 patients. The aim of this study was to evaluate predictors of COVID-19 severity previously proposed. Clinical and demographic characteristics and 120 single-nucleotide polymorphisms were analyzed from 817 patients with COVID-19, who attended the emergency department of the Hospital Universitario de La Princesa during March and April 2020. The main outcome was a modified version of the 7-point World Health Organization (WHO) COVID-19 severity scale (WHOCS); both in the moment of the first hospital examination (WHOCS-1) and of the severest WHOCS score (WHOCS-2). The TMPRSS2 rs75603675 genotype (OR = 0.586), dyslipidemia (OR = 2.289), sex (OR = 0.586), and the Charlson Comorbidity Index (OR = 1.126) were identified as the main predictors of disease severity. Consequently, these variables might influence COVID-19 severity and could be used as predictors of disease development.

Methylenetetrahydrofolate reductase C677T gene polymorphism and the association with dyslipidemia in type 2 diabetic Palestinian patients

BACKGROUND

Dyslipidemia in diabetes is common and characterized by hypertriglyceridemia with decreased levels of high-density lipoprotein. The objective of this study was to assess the prevalence of MTHFR C677T polymorphism in Palestinian T2DM patients and to investigate the association between this polymorphism and lipid profile in diabetic patients with and without dyslipidemia.

METHODS

A total of 208 T2DM patients including 98 with dyslipidemia and 110 without dyslipidemia were enrolled in this study. The MTHFR C677T genotyping was conducted by PCR-RFLP followed by agarose gel electrophoresis.

RESULTS

There were no significant differences in either the genotype distribution or allele frequency in T2DM patients with or without dyslipidemia (37.8% CC, 54% CT, 8.2% TT vs. 48.2% CC, 41.8% CT, 11% TT; p = 0.209). However, among the dyslipidemic group, the TT carriers have a higher HDL level (46.8 ± 17.8) compared to (CC+CT) carriers (34.68 + 11.9) (p = 0.01). In the group without dyslipidemia, there was a significant elevation in diastolic blood pressure (DBP) among the CC carriers (83.6 ± 10.6) compared to those who carried at least one mutant allele (CT+TT) (78.1 ± 11.1) (p = 0.009).

CONCLUSIONS

The study shows that in our Palestinian population the MTHFR 677TT genotype lowers DBP significantly in patients without dyslipidemia and is related to increased level of HDL in diabetic dyslipidemia patients.

Rare variants in MTHFR predispose to occurrence and recurrence of pulmonary embolism

BACKGROUND

Rare genetic variants play a critical role in unprovoked pulmonary embolism (PE). However, the known risk genes only account a small proportion of patients with PE. The objective of this study was to investigate the relationship between the rare variants of gene encoding methylenetetrahydrofolate reductase (MTHFR) and the initiation and long-term clinical outcomes of PE.

METHODS

The rare variants of MTHFR were detected by whole exome sequencing of DNA from 258 unprovoked PE cases and 11,451 controls. Correlation of genotype and clinical phenotype and outcome were evaluated at baseline and after follow-up.

RESULTS

MTHFR rare variants were found in 15 of 258 cases (5.81%) and 241 of 11,451 controls (2.10%), conferring 2.87-fold greater odds of the PE occurrence (OR = 2.87, 95% CI = 1.68-4.91, P = 5.6 × 10^-5, chi-square test). The patients with MTHFR rare variants had higher plasma level of homocysteine than those without. During a follow-up of 3.0 years, a total of 84 events were identified. The recurrent PE (two or more events of PE) were significantly higher in patients carrying MTHFR rare variants (8/15, 53.3%) compared with those without (55/239, 23.0%) (P = 0.023).

CONCLUSION

We speculate that MTHFR rare variants may increase the occurrence and recurrence of PE.

A prospective cohort study of MTHFR C677T gene polymorphism and its influence on the therapeutic effect of homocysteine in stroke patients with hyperhomocysteinemia

BACKGROUND

Hyperhomocysteinemia (HHCY) is a risk factor for cardiovascular and cerebrovascular diseases. The C677T 5, 10-methylenetetrahydrofolate reductase (MTHFR) gene polymorphism increases homocysteine (HCY) levels. This study analyzed the relationship between C677T MTHFR polymorphism and the therapeutic effect of lowering HCY in stroke patients with HHCY.

METHODS

Baseline data were collected from stroke patients with HHCY for this prospective cohort study. The C677T MTHFR genotype was detected by polymerase chain reaction-restriction fragment length polymorphism and the therapeutic effect to reduce HCY was compared.

RESULTS

Of 200 stroke patients 162 (81.0%) completed follow-up and were evaluated. Most of them responded well to treatment (103 cases, 63.5%), but 59 (36.4%) patients were in the poor efficacy group. There was a significant difference in terms of age (P < 0.001), hypertension (P = 0.041), hyperuricemia (P = 0.042), HCY after treatment (P < 0.001), and MTHFR genotype (P < 0.001) between the poor efficacy and effective groups, with increased frequency of the TT genotype in the poor efficacy group. Logistic regression showed that the T allele was associated with poor efficacy (OR = 0.733, 95%CI: 0.693, 0.862, P < 0.001). In the codominant model the TT genotype was associated with poor outcome (OR = 0.862, 95%CI: 0.767, 0.970, P = 0.017) and this was also the case in the recessive model (OR = 0.585, 95%CI: 0.462, 0.741, P < 0.001) but there was no association between CT and TT in the dominant model.

CONCLUSIONS

The T allele and TT genotype of the MTHFR C677T polymorphism was associated with poor HCY reduction treatment efficacy in stroke patients with HHCY.

TRIAL REGISTRATION

The registration number of the clinical trial is ChiCTR1800020048. Registration date: December 12, 2018.

Genes and genetics in hyperhomocysteinemia and the "1-carbon metabolism": implications for retinal structure and eye functions

Homocysteine (Hcy), a sulfur-containing nonproteinogenic amino acid, is generated as a metabolic intermediate. Hcy constitutes an important part of the "1-carbon metabolism" during methionine turnover. Elevated levels of Hcy known as hyperhomocysteinemia (HHcy) results from vitamin B deficiency, lack of exercise, smoking, excessive alcohol intake, high-fat and methionine-rich diet, and the underlying genetic defects. These factors directly affect the "1-carbon metabolism (methionine-Hcy-folate)" of a given cell. In fact, the Hcy levels are determined primarily by dietary intake, vitamin status, and the genetic blueprint of the susceptible individual. Although Hcy performs an important role in cellular functions, genetic alterations in any of the key enzymes responsible for the "1-carbon metabolism" could potentially upset the metabolic cycle, thus causing HHcy environment in susceptible people. As such, HHcy relates to several clinical conditions like atherosclerosis, myocardial infarction, stroke, cognitive impairment, dementia, Parkinson's disease, multiple sclerosis, epilepsy, and ocular disorders, among others. This article summarizes the findings from our laboratory and public database regarding genetics of HHcy and its effects on ocular disorders, their respective management during dysregulation of the 1-carbon metabolism.

Methylenetetrahydrofolate reductase C677T variant and hyperhomocysteinemia in subarachnoid hemorrhage patients from India

Methylenetetrahydrofolate reductase (MTHFR) polymorphism (C677T, A1298C) has been implicated in increased plasma homocysteine (Hcy) levels. The present study was designed to investigate the association between MTHFR polymorphism and increased Hcy levels in subarachnoid haemorrhage (SAH) patients. A total of 150 subjects from North India were included in the study, comprising of 100 SAH patients and 50 healthy controls. Plasma Hcy levels was determined and MTHFR polymorphism (C677T, A1298C) was screened by High resolution melting (HRM) analysis. Plasma Hcy levels were found to be significantly higher (p < 0.001) in SAH patients than in healthy controls. No significant difference in the genotype and allele frequency of MTHFR A1298C was observed. However, frequency of MTHFR C677T genotype, CT (53% vs. 20%; p < 0.001) and TT (15% vs. 2%; p < 0.05) was significantly higher in SAH group as compared to healthy controls. The frequency of T allele (41.5% vs. 12%; p < 0.001) was also found to be higher in SAH patients in comparison to healthy controls. Furthermore, Hcy levels were higher in SAH patients with TT genotype than in patients having CT genotype, whereas CC genotype had lower Hcy levels. The study suggests that higher frequency of MTHFR C677T allele may contribute to etiopathology of SAH through increase in Hcy levels.

Association of RTEL1 gene polymorphisms with stroke risk in a Chinese Han population

We investigated the associations between single nucleotide polymorphisms (SNPs) in the regulator of telomere elongation helicase 1 (RTEL1) gene and stroke in the Chinese population. A total of 400 stroke patients and 395 healthy participants were included in this study. Five SNPs in RTEL1 were genotyped and the association with stroke risk was analyzed. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated using unconditional logistic regression analysis. Multivariate logistic regression analysis was used to identify SNPs that correlated with stroke. Rs2297441 was associated with an increased risk of stroke in an allele model (odds ratio [OR] = 1.24, 95% confidence interval [95% CI] = 1.01-1.52, p = 0.043). Rs6089953 was associated with an increased risk of stroke under the genotype model ([OR] = 1.862, [CI] = 1.123-3.085, p = 0.016). Rs2297441 was associated with an increased risk of stroke in an additive model (OR = 1.234, 95% CI = 1.005, p = 0.045, Rs6089953, Rs6010620 and Rs6010621 were associated with an increased risk of stroke in the recessive model (Rs6089953:OR = 1.825, 95% CI = 1.121-2.969, p =0.01546; Rs6010620: OR = 1.64, 95% CI = 1.008-2.669, p =0.04656;Rs6010621:OR = 1.661, 95% CI = 1.014-2.722, p =0.04389). Our findings reveal a possible association between SNPs in the RTEL1 gene and stroke risk in Chinese population.

MTHFR (C677T) CT genotype and CT-apoE3/3 genotypic combination predisposes the risk of ischemic stroke

The predisposition to ischemic stroke (IS) might involve interactions of several genes and environmental factors. The present study was aimed to evaluate the influence of polymorphisms in methylenetetrahydrofolate reductase (MTHFR-C677T) and apolipoprotein-E (apo-E) as risk factors for IS patients in south Indian population. 200 IS patients and 193 age and sex matched controls were genotyped for MTHFR-C677T and apoE by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) method. Statistically significant association was observed for MTHFR CT genotype (IS-Pooled: OR=4.29; p=5.01×10(-5); IS-Males: OR=4.13; p=0.001; IS-Females: OR=8.62; p=0.027; IS-Large Vessel Disease (LVD)- Pooled: OR=4.14; p=0.0002) and T allele (IS-Pooled: OR=4.82; p=1.49×10(-5); IS-Males: OR=4.33; p=0.0002; IS-Females: OR=7.99; p=0.031; IS-LVD-Pooled: OR=4.13; p=0.0001). Further, reduced frequencies of CC genotype (IS-Pooled: OR=0.20; p=9.80×10(-6); IS-Males: OR=0.25; p=0.001; IS-Females: OR=0.12; p=0.027; IS-LVD-Pooled: OR=0.23; p=0.0001) and C allele (IS-Pooled: OR=0.21; p=1.49×10(-5); IS-Males: OR=0.23; p=0.0002; IS-Females: OR=0.13; p=0.031; IS-LVD-Pooled: OR=0.24; p=0.0001) were observed in IS patients than the controls. No association was observed for apoE genotypes/alleles in IS/LVD cases. Our study demonstrated the presence of risk for MTHFR CT genotype/T allele and 'CT-3/3' (n=33 vs. 5; OR=7.42; p=0.001) genotypic combination in the development of IS in south India. Further, follow-up study of these stroke cases i.e., in later stages of the disease whether they are developing the neurological disorders such as Alzheimer's Disease (AD) and vascular dementia (VaD) is needed to draw a fruitful conclusion in connection between neurological disorders and with these two polymorphisms, before translating it into clinical practice.

Association of APOE (E2, E3 and E4) gene variants and lipid levels in ischemic stroke, its subtypes and hemorrhagic stroke in a South Indian population

In the present study we evaluated the association of APOE (E2/E3/E4) polymorphism with ischemic stroke (n=620), its subtypes and hemorrhagic stroke (n=250) in a South Indian population from Telangana. The genotypes were determined using PCR-RFLP while lipid levels were measured using commercially available kits. We found significant difference in the genotypic distribution between hemorrhagic stroke patients and controls for certain genetic models [E2/E2 vs. E2/E4; E3/E3 vs. E2/E3; E3/E3 vs. E2/E4; E4/E4 vs. E2/E3; E4/E4 vs.E2/E4 and E3 vs. E4]. However, no significant difference was observed in genotypic distribution between ischemic stroke patients and controls. On analysing the genotypic distribution between ischemic and hemorrhagic stroke patients, statistically significant difference was observed in specific genetic models [E2/E2 vs. E2/E4; E3/E3 vs. E2/E3; E3/E3 vs. E2/E4; E4/E4 vs. E2/E3 and E4/E4 vs. E2/E4]. In ischemic stroke subtypes analysing for alleles E3 vs. E2 and E3 vs. E4, we found significant association with intracranial large artery (p=0.01), cardioembolic stroke (p=0.001 and p=0.0004) and lacunar stroke (p=0.02). Analysing the association of various genotypes with different lipid levels significant association was observed for VLDL (P=0.000) and for triglyceride (P=0.000) levels with E2/E4 and E3/E4 genotypes in ischemic stroke but not in hemorrhagic stroke. In conclusion, our results suggest that APOE polymorphism does seem to play a role in hemorrhagic stroke and also in the development of specific subtypes of ischemic stroke. Further, in ischemic stroke VLDL and triglycerides levels were found to be significantly associated with E2/E4 and E3/E4 genotypes.

Insertion/Insertion Genotype of Angiotensin I-Converting-Enzyme Gene Predicts Risk of Myocardial Infarction in North East India

Myocardial infarction (MI) is common in India and the disease occurs at a relatively younger age. We wanted to look for association of Angiotensin I-converting enzyme (ACE) gene with MI in North East India. We also wanted to examine possible environmental interaction of ACE gene with established cardiovascular risk factors in causation of MI. In the study carried out in Assam Medical College, 200 consecutive confirmed cases of MI were recruited. Equal numbers of age- and sex-matched control subjects from hospital workers and patients attending the hospital for diseases unrelated to cardiovascular disease were enrolled. Structured questionnaires were used to note demographic and clinical factors. Cardiovascular risk factors were determined from history, physical examination and biochemical investigations. ACE insertion/deletion (I/D) polymorphism was determined by PCR method. Interaction of ACE gene with other risk factors was noted. The study identified ACE II genotype (odds ratio = 3.02; 95% CI 1.40-6.51), smoking, hypertension, diabetes and serum triglyceride > 150 mg/dl as independent risk factors for MI. ACE II genotype showed greater risk in non-smokers, non-hypertensives, non-diabetics and in subjects with LDL-C < 130 mg/dl. Low HDL cholesterol enhanced the genetic risk. Subjects with ACE II genotype have an independent risk of developing MI, specially in low cardiovascular risk subjects.

Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism: epidemiology, metabolism and the associated diseases

The Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism is associated with various diseases (vascular, cancers, neurology, diabetes, psoriasis, etc) with the epidemiology of the polymorphism of the C677T that varies dependent on the geography and ethnicity. The 5,10-Methylenetetrahydrofolate reductase (MTHFR) locus is mapped on chromosome 1 at the end of the short arm (1p36.6). This enzyme is important for the folate metabolism which is an integral process for cell metabolism in the DNA, RNA and protein methylation. The mutation of the MTHFR gene which causes the C677T polymorphism is located at exon 4 which results in the conversion of valine to alanine at codon 222, a common polymorphism that reduces the activity of this enzyme. The homozygous mutated subjects have higher homocysteine levels while the heterozygous mutated subjects have mildly raised homocysteine levels compared with the normal, non-mutated controls. Hyperhomocysteinemia is an emerging risk factor for various cardiovascular diseases and with the increasing significance of this polymorphism in view of the morbidity and mortality impact on the patients, further prevention strategies and nutritional recommendations with the supplementation of vitamin B12 and folic acid which reduces plasma homocysteine level would be necessary as part of future health education. This literature review therefore focuses on the recent evidence-based reports on the associations of the MTHFR C677T polymorphism and the various diseases globally.

Association between the ACE I/D polymorphism and risk of ischemic stroke: an updated meta-analysis of 47,026 subjects from 105 case-control studies

BACKGROUND

The association between the angiotensin-converting enzyme insertion/deletion (ACE I/D) polymorphism and risk of ischemic stroke (IS) remains controversial and ambiguous. To clarify this association, a large meta-analysis was performed.

METHODS

Electronic databases in both English and Chinese were used to identify relevant studies (updated in February 2014). Odds ratios (ORs) and 95% confidence intervals (95% CIs) were used to describe the strength of the association.

RESULTS

One hundred and fifty eligible studies, including 18,258 IS cases and 28,768 controls, were identified. Meta-analysis of these studies pointed to a significant association between the ACE I/D polymorphism and IS risk: (D vs. I: OR=1.354, 95% CI=1.272-1.440, P<0.001; DD vs. II: OR=1.755, 95% CI=1.561-1.973, P<0.001; ID vs. II: OR=1.178, 95% CI=1.098-1.263, P<0.001; DD vs.

ID/II

OR=1.535, 95% CI=1.399-1.684, P<0.001; DD/ID vs. II: OR=1.353, 95% CI=1.251-1.463, P<0.001). Subgroup analysis revealed a significantly elevated risk among Asians, but with borderline statistical significance among Caucasians.

CONCLUSION

This meta-analysis indicated that the ACE I/D polymorphism may be a genetic susceptibility factor for IS, especially among Asians, but with borderline statistical significance for Caucasians. Further investigations are needed to validate our conclusions.

The role of genetic risk factors in arterial ischemic stroke in pediatric and adult patients: a critical review

The incidence of arterial ischemic stroke (AIS) in childhood (about 2-13 per 100,000 children a year) is much lower than the incidence in the adult population. Still, adverse outcomes of acute brain ischemia in childhood include death (10% of AIS children), neurological sequel, epileptic seizures (over 50%) and recurrence (over 20%). The knowledge of childhood stroke etiopathogenesis is still insufficient and the diagnostic and therapeutic procedures--controversial. Risk factors for childhood stroke differ from those observed in adults due to differing exposure to external risk factors. The most frequently reported risk factors for pediatric ischemic stroke are cerebral arteriopathies and vascular malformations, cardiac diseases, infections, traumas and metabolic diseases. Because of its multifactorial etiology pediatric AIS probably has a multigenic inheritance pattern. The genetic susceptibility to AIS may be determined by specific polymorphic variants encoding markers of hemostasis regulation and they are some of the most important targets in searching for genetic determinants in pediatric AIS. The authors have reviewed the recent literature on risk factors of childhood ischemic stroke with the focus on genetic factors like polymorphisms of genes encoding coagulation factors II, V, VII and XIII, MTHFR, fibrinogen beta, and compared them with the results performed in adult patients.

Apolipoprotein E polymorphisms and ischaemic stroke: a two-center Greek study

BACKGROUND AND PURPOSE

Apolipropotein E(apoE) is a plasma protein exhibiting three common isoforms (E2, E3, E4). Its involvement in lipoprotein metabolism may have an impact on stroke occurrence. As results in the literature are inconclusive further studies are needed to elucidate its role. Our objective was to study the role of apoE isoforms and the interplay with environmental risk factors in patients with first ischaemic stroke occurrence in the Greek population.

METHODS

Three hundred and twenty-nine patients with first-ever ischaemic stroke were included in our study. Strokes of cardioembolic origin and patients with autoimmune or prothrombotic syndromes were excluded. A control group of 361 subjects with no stroke history were also included in our study. Risk factors (hyperlipidemia, hypertension, diabetes mellitus and smoking) were assessed. ApoE alleles were determined in all subjects participating in the study.

RESULTS

Genotype ε3/ε3 was found to have a protective role against stroke occurrence compared with other genotypes (odds ratio 0.674, 95% confidence interval 0.480-0.946) especially in the female patient subgroup. In multivariate analysis after adjustment for age, body mass index (BMI), hypertension, dyslipidemia, diabetes mellitus and smoking, the role of genotype was limited and outweighed by risk factors in both genders. No association between apoE alleles and BMI, cholesterol, triglycerides or high-density lipoprotein plasma levels was noted.

CONCLUSIONS

Our study was indicative of a protective role of the ε3/ε3 genotype, especially in female patients. However, risk factors such as age, BMI, hypertension, dyslipidemia, diabetes mellitus and smoking have a strong impact on stroke occurrence and outweigh the protective role of the ε3/ε3 genotype.

A magnetic nanoparticles-based method for DNA extraction from the saliva of stroke patients

C677T polymorphism in the methylenetetrahydrofolate reductase (MTHFR) gene is a risk factor for stroke, suggesting that widespread detection could help to prevent stroke. DNA from 70 stroke patients and 70 healthy controls was extracted from saliva using a magnetic nanoparticles-based method and from blood using conventional methods. Real-time PCR results revealed that the C677T polymorphism was genotyped by PCR using DNA extracted from both saliva and blood samples. The genotype results were confirmed by gene sequencing, and results for saliva and blood samples were consistent. The mutation TT genotype frequency was significantly higher in the stroke group than in controls. Homocysteine levels were significantly higher than controls in both TT genotype groups. Therefore, this noninvasive magnetic nanoparticles-based method using saliva samples could be used to screen for the MTHFR C677T polymorphism in target populations.

Angiotensinogen gene polymorphism and ischemic stroke in East Asians: A meta-analysis

Objective:

To investigate the association between angiotensinogen gene M235T polymorphism and ischemic stroke in East Asians.

Data Retrieval:

A computer-based online search was conducted in PubMed, Google scholar, China National Knowledge lnfrastructure database between January 1990 and April 2012 for relevant studies. The key words were angiotensinogen or AGT, polymorphism or genetic and ischemic stroke or cerebral infarction.

Selection Criteria:

Case-controlled studies addressing the correlation between angiotensinogen gene M235T polymorphism and ischemic stroke in East Asians were included. The distribution of genotypes in the included studies was tested for Hardy-Weinberg equilibrium. Quality evaluation of the included studies was conducted by two physicians. Statistical analyses were carried out using Stata 12.0 software for meta-analysis. Heterogeneity tests, sensitivity analysis and publication bias were also conducted.

Main Outcome Measures:

The association between angiotensinogen gene M235T polymorphism and ischemic stroke risk in East Asians was assessed.

Results:

Six relevant studies involving 891 patients with ischemic stroke and 727 controls were included in this meta-analysis. Results showed that there was a significant association between angiotensinogen gene M235T polymorphism and the risk of ischemic stroke in East Asians (T vs. M: odds ratio (OR) = 1.54, 95% confidence interval (CI) = 1.10–2.16; TT vs. MM: OR = 2.24, 95%CI = 1.37–3.66; TT vs. MT: OR = 1.76, 95%CI = 1.41–2.20; MM + MT vs. TT: OR = 0.57, 95%CI = 0.46–0.70). Sensitivity analysis confirmed that the study results were stable and reliable, with no publication bias.

Conclusion:

The angiotensinogen gene M235T polymorphism is associated with ischemic stroke in East Asians, and the TT genotype and T allele are risk factors for ischemic stroke.

Association between the apolipoprotein E gene polymorphism and ischemic stroke in Chinese populations: New data and meta-analysis

Ischemic stroke (IS) is a complex multifactorial inherited disease. Many studies have focused on the potential genetic effects of apolipoprotein E (ApoE) gene polymorphism on IS. However, inconsistencies still exist in the association of ApoE gene polymorphism with IS. The aim of this study was to investigate the ApoE gene polymorphism in relation to IS in the Guangxi Han populations and assess the risk of various ApoE genotypes associated with IS in Chinese populations. We conducted a case-control study involving a total of 166 IS cases and 192 healthy controls to investigate the association of ApoE gene polymorphism with IS in the Guangxi Han populations. Furthermore, we performed a meta-analysis to investigate whether the ApoE gene polymorphism is associated with IS in Chinese populations. There was no evidence for a significant association between ApoE gene polymorphism and IS in the Guangxi Han populations (ɛ2/ɛ2 vs. ɛ3/ɛ3: OR=1.25, 95% CI=0.08–20.17; ɛ2/ɛ3 vs. ɛ3/ɛ3: OR=1.49, 95% CI=0.79–2.79; ɛ2/ɛ4 vs. ɛ3/ɛ3: OR=1.25, 95% CI=0.17–9.00; ɛ3/ɛ4 vs. ɛ3/ɛ3: OR=1.10, 95% CI=0.60–2.04; ɛ4/ɛ4 vs. ɛ3/ɛ3: OR=2.50, 95% CI=0.22–27.87; allele ɛ2 vs. allele ɛ3: OR=1.39, 95% CI=0.80–2.44; allele ɛ4 vs. allele ɛ3: OR=1.16, 95% CI=0.68–1.98). In our meta-analysis, a significant association of ApoE gene polymorphism with IS was found in the genetic model of ɛ2/ɛ4 vs. ɛ3/ɛ3 (OR=2.04, 95% CI=1.45–2.85), ɛ3/ɛ4 vs. ɛ3/ɛ3 (OR=1.93, 95% CI=1.42–2.62), ɛ4/ɛ4 vs. ɛ3/ɛ3 (OR=3.41, 95% CI=2.17–5.34) and allele ɛ4 vs. allele ɛ3 (OR=2.34, 95% CI=1.91–2.86). However, no clear associations were found in the model of ɛ2/ɛ2 vs. ɛ3/ɛ3 (OR=1.56, 95% CI=0.90–2.71), ɛ2/ɛ3 vs. ɛ3/ɛ3 (OR=0.93, 95% CI=0.79–1.09) and allele ɛ2 vs. allele ɛ3 (OR=1.10, 95% CI=0.97–1.25). In conclusion, no association was found between ApoE gene polymorphism and IS in the Guangxi Han populations, while the results of the meta-analysis indicate that the ApoE mutation allele ɛ4 increases the risk of IS in Chinese populations.

Association of MTHFR C667T polymorphism with bone mineral density and fracture risk: an updated meta-analysis

This meta-analysis investigated the association of C677T polymorphism in MTHFR gene with bone mineral density (BMD) and fracture risk. The results suggested that C677T polymorphism was marginally associated with fracture risk. In addition, this polymorphism was modestly associated with BMD of lumbar spine, femoral neck, total hip, and total body, respectively.

INTRODUCTION

The methylenetetrahydrofolate reductase (MTHFR) gene has been implicated in the regulation of BMD and, thus, may serve as a potential risk factor for the development of fracture. However, results have been inconsistent. In this study, a meta-analysis was performed to clarify the association of C677T polymorphism in MTHFR gene with BMD and fracture risk.

METHODS

Published literature from PubMed and EMBASE were searched for eligible publications. Pooled odds ratio (OR) or weighted mean difference (WMD) and 95% confidence interval (CI) were calculated using a fixed- or random-effects model.

RESULTS

Twenty studies (3,525 cases and 17,909 controls) were included in this meta-analysis. The TT genotype of C677T polymorphism was marginally associated with an increased risk of fracture under recessive model (TT vs. TC + CC: OR = 1.23, 95% CI 1.04-1.47). Using this model, similar results were found among East Asians (OR = 1.40, 95% CI 1.07-1.83), female subpopulation (1.27, 95% CI 1.04-1.55), cohort studies (OR = 1.24, 95% CI 1.08-1.44), and subjects younger than aged 60 years (OR = 1.51, 95% CI 1.10-2.07). In addition, under homogeneous co-dominant model, there was a modest association of C677T polymorphism with BMD of lumbar spine (WMD = -0.017 g/cm(2); 95%CI, -0.030-(-0.005) g/cm(2)), femoral neck (WMD = -0.010 g/cm(2); 95% CI -0.017-(-0.003) g/cm(2)), total hip (WMD = -0.013 g/cm(2), 95% CI -0.022-(-0.004) g/cm(2)), and total body (WMD = -0.020 g/cm(2); 95% CI -0.027-(-0.013) g/cm(2)), respectively.

CONCLUSIONS

This meta-analysis suggested that C677T polymorphism was marginally associated with fracture risk. In addition, this polymorphism was modestly associated with BMD of lumbar spine, femoral neck, total hip, and total body, respectively.

ABO blood group system and gastric cancer: a case-control study and meta-analysis

This study focuses on the association between the ABO blood group system and the risk of gastric cancer or Helicobacter pylori infection. The data for the ABO blood group was collected from 1045 cases of gastric cancer, whereby the patient underwent a gastrectomy in Ruijin Hospital, Shanghai. The information on the ABO blood group from 53,026 healthy blood donors was enrolled as control. We searched the Pubmed database on the relationship between ABO blood groups and gastric cancer risk for meta-analysis. In our case-control study, the risk of gastric cancer in blood group A was significantly higher than that in non-A groups (O, B and AB) (odd ratio, OR1.34; 95% confidential interval, CI 1.25-1.44). Compared with non-O groups (A, B and AB), individuals with blood group O demonstrated a reduced risk of gastric cancer (OR = 0.80; 95% CI 0.72-0.88). The proportion of H. pylori infection in blood group A individuals was significantly higher than that in non-A blood groups (OR = 1.42; 95% CI 1.05-1.93). We further combined our data with the published data of others, and crossreferenced the risk of gastric cancer with the blood type, finding consistent evidence that gastric cancer risk in the blood A group was higher than that in the non-A groups (OR = 1.11; 95% CI 1.07-1.15), and that blood type O individuals were consistently shown gastric cancer risk reduction (OR = 0.91; 95% CI 0.89-0.94). Our study concluded that there was a slightly increased risk of gastric cancer in blood group A individuals, and people with blood type A are more prone to be infected by H. pylori than other ABO blood type individuals, whereas, a slightly decreased risk of gastric cancer was identified in blood type O individuals.

Large-scale meta-analysis of genetic studies in ischemic stroke: Five genes involving 152,797 individuals

BACKGROUND:

Ischemic stroke descent has a genetic basis. Stroke represents a complex trait, which is assumed to be polygenic. On this topic, the role of a wide number of candidate genes has been investigated in stroke through association studies.

MATERIALS AND METHODS:

We performed a literature-based systematic review of genetic association studies in stroke abound several populations. Odds ratios (ORs) and 95% confidence intervals (CIs) were determined for each gene-disease association. Following a review of 300 manuscripts, five candidate gene variants were analyzed among 152,797 individuals (45,433 cases and 107,364 controls).

RESULTS:

For these five candidate genes studied, the prothrombin OR is 1,57 (1,23-2,89), the factor V Leiden OR is 1,43 (0,67-6,24), the mean OR of angiotensin I converting enzyme (ACE) insertion/deletion (I/D) polymorphism is 1,11 (1,02-1,25), the summary OR for the C677T variant of 5,10-methylenetetrahydrofolate reductase (MTHFR) is 1,23 (0,61-1,47) and the pooled OR for the apolipoprotein E (APOE) gene is 0,95 (0,77-1,14) .

CONCLUSION:

These data suggest the genetic associations of some genes with ischemic stroke and it is necessary to compete with other genes. Our findings could represent an epidemiological base and a useful tool to address further molecular investigations and to realize more detailed meta-analyses.

Angiotensin-converting enzyme insertion/deletion polymorphism contributes to ischemic stroke risk: a meta-analysis of 50 case-control studies

Background

Many studies have investigated the association between the angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and risk of ischemic stroke. However, the evidence is inadequate to draw robust conclusions because most studies were generally small and conducted in heterogeneous populations. To shed light on these inconclusive findings, we conducted a large meta-analysis of studies relating the ACE I/D polymorphism to the risk of ischemic stroke.

Methods

Relevant studies were identified by searching PubMed and Embase through February 2012 and by reviewing the references of retrieved articles. We included studies that reported odds ratio (OR) with 95% confidence interval (CI) for the association between this polymorphism and ischemic stroke risk.

Results

Fifty independent publications, with 10 070 stroke cases and 22 103 controls, were included. The results indicated that the DD homozygote carriers had a 37% higher risk of ischemic stroke when compared with the homozygotes II and heterozygote ID [odds ratio (OR) = 1.37, 95% confidence interval (CI): 1.22–1.53]. Subgroup analyses indicated that this higher risk was more pronounced among Asians, hospital-based studies, and small vessel disease (SVD). Potential publication bias may exist, but correction for this bias using a formal statistical method did not materially alter the combined risk estimate.

Conclusion

The results of our meta-analysis indicate that the D allele of ACE I/D polymorphism is a low-penetrance susceptibility marker of ischemic stroke.

The TT genotype of methylenetetrahydrofolate reductase 677C>T polymorphism increases the susceptibility to pediatric ischemic stroke: meta-analysis of the 822 cases and 1,552 controls

The 677C>T polymorphism within methylenetetrahydrofolate reductase (MTHFR) gene is related to an elevated level of homocysteine. Thus it may be considered as a genetic risk factor in ischemic stroke. Apparently studies of this type of polymorphism in childhood stroke have shown conflicting results. We performed meta-analysis of all the data that are available in relation with MTHFR polymorphism and the risk of ischemic stroke in children. We searched PubMed (last search dated December 2010) using "MTHFR polymorphism", "ischemic stroke" "child", "children", "pediatric stroke" as keywords and reference lists of studies and reviews on the topic. Finally, 15 case-control studies corresponded to the inclusion criteria for meta-analysis. These studies involved the total number of 822 children and adolescents after ischemic stroke and 1,552 control subjects. Fixed or random effects models were used depending on the heterogeneity between the studies. The association between ischemic stroke and 677C>T polymorphism within MTHFR gene was observed in three of the studies. The pooled analysis showed that TT genotype of MTHFR gene is more common in stroke patients than in controls (p = 0.0402, odds ratio = 1.57, 95 % confidence interval 1.02-2.41). The Egger's test did not reveal presence of a publication bias. The results based on a sizeable group of cases and controls have proved that the 677C>T polymorphism in MTHFR gene is associated with the development of ischemic stroke in children.

Single nucleotide polymorphisms (SNPs) of pro-inflammatory/anti-inflammatory and thrombotic/fibrinolytic genes in patients with acute ischemic stroke in relation to TOAST subtype

BACKGROUND

The genetic basis of complex diseases like ischemic stroke probably consists of several predisposing risk factors, such as genes involved in inflammation and thrombotic pathways. On this basis the aim of our study was to evaluate the role of SNPs (single nucleotide polymorphisms) of some pro-inflammatory/anti-inflammatory and coagulation/fibrinolytic genes in patients with acute ischemic stroke.

METHODS

The study population consisted of 144 consecutive Caucasian adult patients who were hospitalized in the Internal Medicine Department at the University of Palermo between November 2006 and January 2008, and who met inclusion criteria. The cases were patients admitted with a diagnosis of acute ischemic stroke, and age-matched (± 3 years) control subjects: patients admitted to our Internal Medicine Department for any cause other than acute cardiovascular and cerebrovascular events and for routine checkup examinations. Molecular analysis of alleles at the -308 nucleotide (-308G/A) of TNF-α gene, -1082/-819 haplotypes of IL-10 gene, IL-1RN exon 2 VNR polymorphism, alleles at the -174 nucleotide (-174G/C) of IL-6 gene, PAI-1675 5G/4G polymorphism, alleles at the -7351 nucleotide (-7351C/T) of tPA gene was undertaken in both patient groups.

RESULTS

We analyzed 96 subjects with acute ischemic stroke and 48 control subjects. We observed a significantly higher frequency of IL-10 1082 AA genotype in stroke patients with a significant risk trend. We also reported a higher frequency in stroke subjects with a significant risk trend of the TPA 7351-CT genotype and of IL-1RN-VNTR 86 bp 2/2 genotype. Moreover, we observed a significant relationship with TOAST subtype only with regard to CC TPA genotype and 1/1 IL-1 VNTR 86 bp and lacunar strokes.

CONCLUSIONS

Ischemic stroke is a common multifactor disease, which is affected by a number of genetic mutations and environmental factors. Our findings showing a relationship between pro-inflammatory/anti-inflammatory and thrombotic/fibrinolytic genes SNPs and ischemic stroke may contribute to delineate a possible stroke risk profile in subjects with cerebrovascular risk factors.

Is C677T polymorphism in methylenetetrahydrofolate reductase gene a risk factor for diabetic nephropathy or diabetes mellitus in a Chinese population?

BACKGROUND AND AIMS

To date, case-control studies on the association between C677T polymorphism in methylenetetrahydrofolate reductase (MTHFR) gene and diabetes mellitus (DM) or diabetic nephropathy (DN) in different populations have provided inconclusive results. To clarify the effect of the C677T polymorphism on the risk of both DM and DN in a Chinese population, a meta-analysis was performed.

METHODS

A comprehensive literature search was conducted to collect data from all case-control observational studies that investigated association of C677T polymorphism in MTHFR gene with DM or DN in a Chinese population.

RESULTS

Overall, 12 studies in a Chinese population published up to 2011 were combined, and the heterogeneity among them varied from none to moderate. The 677T allele showed significant association with DN (OR = 1.97, 95% CI [1.71, 2.28], p <0.00001), but no relationship with DM (OR = 1.03, 95% CI [0.89, 1.18], p = 0.70) compared with the 677C allele in a Chinese population. Similarly, evidence of significant association with DN was detected in the additive model, the recessive model and the dominant model for allele T (additive model: OR = 3.26, 95% CI [2.46, 4.31], p <0.00001; recessive model: OR = 2.32, 95% CI [1.81, 2.97], p <0.00001; dominant model: OR = 2.35, 95% CI [1.89, 2.91], p <0.00001); however, no relationship with DM was found (additive model: OR = 1.01, 95% CI [0.76, 1.35], p = 0.94; recessive model: OR = 0.98, 95% CI [0.76, 1.26], p = 0.87; dominant model: OR = 1.23, 95% CI [0.91, 1.65], p = 0.18). There were no sources of bias in the selected studies, and the sensitivity analysis (exclusion of studies not in Hardy-Weinberg equilibrium) suggested stability of this meta-analysis.

CONCLUSIONS

C677T polymorphism in MTHFR gene may be a risk factor for DN, but not for DM, in a Chinese population.

The utility of collaborative biobanks for cardiovascular research

Differences between animal and human atherosclerosis have led to the requirement for clinical data, imaging information and biological material from large numbers of patients and healthy persons. Where such "biobanks" exist, they have been fruitful sources for genomewide association, diagnostic accuracy, ethnicity, and risk stratification cohort studies. In addition once established, they attract funding for future projects. Biobanks require a network of medical contributors, secure storage facilities, bioinformatics expertise, database managers, and ethical working practices to function optimally. There is the opportunity for collaboration between individual biobanks to further amplify the advantages afforded.

Association Between VEGF Polymorphisms and Homocysteine Levels in Patients With Ischemic Stroke and Silent Brain Infarction

Background and Purpose—

Vascular endothelial growth factor (VEGF) plays a role in atherosclerosis-related diseases such as cerebrovascular or cardiovascular diseases. However, the effect of VEGF -2578C>A, -1154G>A, -634G>C, and 936C>T polymorphisms on the susceptibility to stroke and silent brain infarction has not been reported.

Methods—

Using polymerase chain reaction-amplified DNA, VEGF polymorphisms were analyzed in 615 patients with ischemic stroke, 376 patients with silent brain infarction, and 494 control subjects.

Results—

The AA and CC+CA ( C allele bearing) genotype frequencies of the -2578C>A polymorphism and the CT+TT ( T allele-bearing) genotype frequency of the 936C>T polymorphism were significantly different between the stroke and control groups (false discovery rate-adjusted probability values of 0.016, 0.044, and 0.044, respectively). When stratified by the size of the occluded vessel, the VEGF polymorphisms were associated with patients with multiple small-artery occlusions. Several haplotypes of the VEGF polymorphisms were significantly different between the control and stroke groups. With respect to silent brain infarction, the difference in the frequency of the -634G>C polymorphism between the GC+CC ( C allele-bearing) genotype and the controls was marginally significant (false discovery rate-adjusted probability value of 0.056). On the other hand, the -634G>C and 936C>T polymorphisms were associated with plasma homocysteine levels of patients with multiple or single small-artery occlusions, respectively.

Conclusions—

This study suggests that VEGF polymorphisms and haplotypes are possible genetic determinants for the risk of ischemic stroke, particularly in patients with multiple small-artery occlusions. However, VEGF polymorphisms had only a weak association with plasma homocysteine levels in the Korean population.

Activation of transient receptor potential vanilloid 1 by dietary capsaicin delays the onset of stroke in stroke-prone spontaneously hypertensive rats

BACKGROUND AND PURPOSE

Previous studies show that endothelial nitric oxide synthase (eNOS) plays a prominent role in maintaining cerebral blood flow and preventing stroke. Capsaicin in hot pepper can increase the phosphorylation of eNOS in endothelial cells. We test the hypothesis that chronic dietary capsaicin can prevent stroke through activation of cerebrovascular transient receptor potential vanilloid 1 (TRPV1) channels in stroke-prone spontaneously hypertensive rats (SHRsp).

METHODS

SHRsp were fed dietary capsaicin, and their onset of stroke was examined. TRPV1 knockout and transgenic mice were used for determining the function of TRPV1 channels. Expression of eNOS and cerebrovascular reactivity were examined.

RESULTS

Immunofluorescence showed TRPV1 channels and eNOS coexpression in cerebral arterioles. Administration of capsaicin significantly increased phosphorylated eNOS in carotid arteries from wild-type mice but not in TRPV1 knockout mice. Inhibition of eNOS using N(G)-nitro-L-arginine methyl ester, removal of endothelium, or mutant TRPV1 significantly reduced capsaicin-induced endothelium-dependent relaxation of basilar arteries in mice. Chronic dietary capsaicin also remarkably increased eNOS expression in carotid arteries from SHRsp. Compared with Wistar-Kyoto rats, SHRsp had impaired endothelium-dependent relaxation of basilar arteries. Administration of capsaicin or L-arginine significantly improved the endothelium-dependent relaxation of basilar arteries in SHRsp. SHRsp had hypertrophy of cerebral arterioles, which was reversed by dietary capsaicin. Importantly, long-term administration of capsaicin significantly delayed the onset of stroke and increased the survival time in SHRsp.

CONCLUSIONS

Activation of TRPV1 channels by dietary capsaicin mediated increases in phosphorylation of eNOS and could represent a novel target for dietary intervention of stroke.

Evaluation of MTHFR C677T polymorphism in ischemic and hemorrhagic stroke patients. A case-control study in a Northern Indian population

OBJECTIVE

The present study was aimed to evaluate MTHFR C677T gene polymorphism in patients with ischemic stroke (IS) and intracerebral hemorrhage (ICH) and compare it with controls.

METHODS

207 patient with IS and 215 with CT/MRI proven ICH were included and compared with 188 healthy controls. The stroke risk factors, location of IS, its vascular territory and in ICH the location of hematoma were noted. MTHFR C677T polymorphism was studied by polymerase chain reaction.

RESULTS

Hypertension was present in 65.9% of ICH and 48.8% of IS. Other stroke risk factors were not significantly different. The frequency of the CC genotype in controls was 68.6%. CT in 28.7% and TT in 2.7%, whereas it was 75.3%, 20.5% and 4.2% in ICH and 66.2%, 39.4% and 2.4% respectively in IS. The frequency of these genotypes as well as allele frequency was not different in IS, ICH as compared to controls, however variant allele was more frequent in IS compared to ICH. Homocysteine level was higher in IS patients with variant genotype

INTERPRETATION

MTHFR C677T gene polymorphism was neither associated with hemorrhagic nor ischemic stroke. However raised homocysteine levels were found to be associated with MTHFRC677-TT genotype in IS patients.

Bio-Repository of DNA in stroke (BRAINS): a study protocol

Background

Stroke is one of the commonest causes of mortality in the world and anticipated to be an increasing burden to the developing world. Stroke has a genetic basis and identifying those genes may not only help us define the mechanisms that cause stroke but also identify novel therapeutic targets. However, large scale highly phenotyped DNA repositories are required in order for this to be achieved.

Methods

The proposed Bio-Repository of DNA in Stroke (BRAINS) will recruit all subtypes of stroke as well as controls from two different continents, Europe and Asia. Subjects recruited from the UK will include stroke patients of European ancestry as well as British South Asians. Stroke subjects from South Asia will be recruited from India and Sri Lanka. South Asian cases will also have control subjects recruited.

Discussion

We describe a study protocol to establish a large and highly characterized stroke biobank in those of European and South Asian descent. With different ethnic populations being recruited, BRAINS has the ability to compare and contrast genetic risk factors between those of differing ancestral descent as well as those who migrate into different environments.

Apolipoprotein E Genotype and Cardiovascular Diseases in the Elderly

The apolipoprotein E (APOE) genotype is a genetic risk factor for dementia, Alzheimer’s disease, and cardiovascular disease (CVD). It includes three alleles (e2, e3, e4) that are located on chromosome 19q3.2. The e3 allele is the most common and is more common in people of Northern European ancestry and less common in those of Asian ancestry. Those with at least one e4 allele are at increased risk for CVD outcomes. It is well established that the presence of an e4 allele is linked to higher low-density lipoprotein cholesterol levels, even at young ages. Even though most CVD occurs in older people, there are few studies of the effects of APOE on CVD in older people. This review addresses recent research on the links between APOE, CVD, and vascular mechanisms by which APOE may affect CVD in the elderly.

Angiotensin-converting enzyme insertion/deletion polymorphism has no effect on the risk of atherosclerotic stroke or hypertension

BACKGROUND AND PURPOSE

Stroke is a heterogeneous multifactorial disease. Hence, a large number of candidate genes are involved in stroke pathophysiology, such as blood pressure regulation and atherosclerosis. Although angiotensin-converting enzyme insertion/deletion (ACE I/D) polymorphism is considered to have a role in hypertension, coronary artery disease, and myocardial infarction, its relationship with cerebrovascular disease and hypertension in stroke in different ethnic populations is still inconsistent.

METHODS

ACE I/D polymorphism, detected by polymerase chain reaction (PCR), was studied in 97 patients with large-vessel and 60 patients with small-vessel atherosclerotic stroke (44 asymptomatic, 16 symptomatic lacunes) and 85 healthy subjects with normal brain imaging. The demographic data, lipid profile and risk factors of patients and controls were obtained retrospectively.

RESULTS

ACE genotypes were in Hardy-Weinberg equilibrium in both patients and controls. Prevalences of DD, ID and II genotype were 41%, 40%, and 19%, respectively, in the stroke group. Differences in ACE I/D polymorphism distribution were statistically insignificant between the groups. This lack of association between stroke and ACE I/D polymorphism did not change in the presence of traditional risk factors (hypertension, diabetes mellitus, smoking, and dyslipidemia). Although hypertension was significantly more common in the patient groups, ACE I/D polymorphism showed no effect on hypertension risk. This lack of association also did not change according to groups or in the presence of diabetes mellitus, male gender or smoking.

CONCLUSION

ACE I/D polymorphism did not predict the risk of stroke or hypertension in our population living in the western Black Sea region of Turkey.

Gene polymorphisms and risk of adult early-onset ischemic stroke: A meta-analysis

INTRODUCTION

Genetic studies restricted to young adult ischemic stroke patients may help in excluding the potentially confounding variables encountered with advanced age; thus, allowing a more precise risk evaluation derived from the inherited mutations alone. Through meta-analysis, this study was conducted to determine the genetic risk contributed by each susceptibility gene polymorphism, particularly in adult early-onset ischemic stroke patients.

MATERIALS AND METHODS

Electronic databases were searched for all the case-control studies relating to any candidate genes for ischemic stroke. The range of age was 18-50 years for cases. Fixed or random effects model was used depending on the heterogeneity between studies.

RESULTS

Twenty-six studies were finally included in this meta-analysis; these studies focused on 7 candidate genes. A significant but modest association was identified for 2 polymorphisms, namely, methylenetetrahydrofolate reductase (MTHFR) C677T (OR = 1.44, 95% CI = 1.14-1.80) and apolipoprotein E (ApoE) epsilon2-4 (OR = 2.53, 95% CI = 1.71-3.73). Although the pooled analysis for platelet glycoprotein Ia (GPIa) C807T showed a positive association (OR = 1.50, 95% CI=1.10-2.05), the Egger's test indicated the existence of publication bias (t=5.27, P>|t|=0.034).

CONCLUSIONS

Genetic abnormalities specific to homocysteine and lipid metabolism increase the risk for ischemic stroke at an early age. These data may offer important implications for future genetic association studies for stroke.

Lupus anticoagulants and anti-phospholipid antibodies as risk factors for a first episode of ischemic stroke

BACKGROUND

Antiphospholipid antibodies (aPLA) and lupus anticoagulant (LAC) were shown to precipitate thromboembolic events. Their association with ischemic stroke remains to be seen.

OBJECTIVES

We investigated the contribution of LAC, and antibodies directed against the phospholipids cardiolipin (aCL), phosphatidylserine (aPS), and the phospholipid-dependent cofactors beta2-glycoprotein I and annexin V, to the risk for ischemic stroke.

PATIENTS/METHODS

LAC and antibody levels were measured in 208 stroke patients and 203 age- and gender-matched control subjects.

RESULTS

Positive LAC resulted in an increased risk for stroke [OR (95% CI) = 8.1 (2.4-27.5)]. Significant elevation in aPS IgG, aCL IgM and aCL IgG titers, and increased prevalence of elevated aPS IgG, aCL IgM and aCL IgG (based on P95 cutoff values of healthy individuals) were seen in patients. aPS IgG was associated with cardioembolic, whereas aCL IgG and IgM were elevated in lacunar, atherosclerotic and cardioembolic, and LAC positivity was documented only in lacunar stroke subtypes. The co-presence of LAC with a positive aCL IgM/IgG or aPS IgG did not affect the overall risk for stroke. Multivariate analysis confirmed the association of positive LAC with stroke [aOR (95% CI) = 9.7 (1.8-52.5)], and demonstrated a clear gradation of increasing risk of stroke associated with the four categories of aCL IgG and aPS IgG, and identified aCL IgM P95 as independent predictors of stroke after adjusting for potentially confounding covariates.

CONCLUSIONS

Our study demonstrates that the presence of LAC, and elevated aCL IgG and aPS IgG antibodies are risk factors for stroke.

Homocystine levels, polymorphisms and the risk of ischemic stroke in young Asian Indians

BACKGROUND

Homocysteine has been for a fairly long time been debated to be a risk factor for stroke. Opinions are divided as to whether raised levels of homocysteine seen in stroke patients are the cause or consequence of stroke. A large number of studies have been conducted in the Caucasian as well as on the Oriental population, which tend to suggest contradictory findings at many times. However, there have been no reports forthcoming from the Asian Indian population, which is a genetically different population than the previously studied populations.

SUBJECTS AND METHODS

In our present study, we looked at homocysteine levels and four commonly seen polymorphisms of homocysteine metabolizing enzymes and their respective prevalence in 120 acute onset ischemic stroke patients compared with an equal number of age and gender matched healthy population. We also tested the influence of folic acid dosage (5 mg OD) on the levels of homocysteine and the allied vitamin supplements, vitamin B12 and folate in smaller groups selected from the larger group.

RESULTS AND CONCLUSIONS

We found homocysteine levels to be significantly raised in the stroke population compared with healthy controls [patients: 12 micromol/L (range: 5.3-39.1 micromol/L), controls: 11.2 micromol/L (range: 6.2-14.2 micromol/L); P =0.001]. There was an almost total response to folic acid dosage as all hyperhomocysteinemic patients showed lowering of homocysteine levels in response to the dosage. The MTHFR 677 C > T polymorphisms showed association with both homocysteine levels as well as stroke (P < 0.001). Nutritional deficiency plays a dominant role in hyperhomocysteinemic conditions in our stroke population, however. Genetic determinants of homocysteine level may also have some part in determining hyperhomocysteinemic conditions in the Asian Indian populations.

Association between renin-angiotensin-aldosterone system genotypes and haplotypes and risk of ischemic stroke of atherosclerotic etiology

OBJECTIVE

The association of renin C-4063T and angiotensinogen (AGT) T174M, AGT M235T and AGT A-6G polymorphisms with ischemic stroke of atherosclerotic etiology was investigated in 329 Tunisian patients with stroke and 444 controls.

MATERIALS AND METHODS

Genotyping was performed using PCR-RFLP and the contributions of polymorphisms to the risk of stroke were analyzed using haplotype and multivariate regression analysis.

RESULTS

AGT 235T and AGT-6G allele and AGT 235T/T, AGT-6A/G and AGT-6G/G genotype frequencies were higher in patients. Linkage disequilibrium (LD) was noted for AGT174T with AGT235M and AGT(-6)A in patients, while AGT235M was in LD with AGT(-6)A in controls and AGT235T was in LD with AGT(-6)G in both groups. The AGT 174T/235T/-6A and AGT 174T/235M/-6G haplotypes were positively and negatively associated with stroke respectively. Multivariate regression analysis identified AGT 174T/235M/-6A, AGT 174T/235T/-6G, AGT 174T/235T/-6A and AGT 174M/235T/-6A haplotypes to be significantly associated with an increased risk of stroke.

CONCLUSIONS

Renin-angiotensin-aldosterone system polymorphisms influence the risk of atherosclerotic stroke in Tunisians.

Genetic epidemiology in aging research

Over the last two decades, aging research has expanded to include not only age-related disease models, and conversely, longevity and disease-free models, but also focuses on biological mechanisms related to the aging process. By viewing aging on multiple research frontiers, we are rapidly expanding knowledge as a whole and mapping connections between biological processes and particular age-related diseases that emerge. This is perhaps most true in the field of genetics, where variation across individuals has improved our understanding of aging mechanisms, etiology of age-related disease, and prediction of therapeutic responses. A close partnership between gerontologists, epidemiologists, and geneticists is needed to take full advantage of emerging genome information and technology and bring about a new age for biological aging research. Here we review current genetic findings for aging across both disease-specific and aging process domains. We then highlight the limitations of most work to date in terms of study design, genomic information, and trait modeling and focus on emerging technology and future directions that can partner genetic epidemiology and aging research fields to best take advantage of the rapid discoveries in each.

Relationship of apoE polymorphism with lipoprotein(a), apoA, apoB and lipid levels in atherosclerotic infarct

BACKGROUND AND PURPOSE

Apolipoprotein E (apoE) polymorphism is suggested to be a risk factor in stroke in some populations, either by affecting lipid parameters or independently. Its effect on lipoprotein(a) [Lp(a)] is not known. The roles of apoE polymorphism and of high Lp(a) levels in atherosclerotic stroke (AS) in the Turkish population are unclear. Our aim was to investigate the relationship of apoE alleles and Lp(a) level with AS and the relationship of apoE alleles with Lp(a) and other lipid parameters.

METHODS

ApoE polymorphisms and lipid parameters were prospectively evaluated in 85 patients and 77 controls with normal brain imaging.

RESULTS

Only hypertension, diabetes mellitus, associated vascular diseases and decreased high-density lipoprotein cholesterol levels were found to be independent risk factors for stroke. However, in the presence of apoE/E4 allele, increased low-density lipoprotein cholesterol (LDL-chol), apolipoprotein B (apoB) and Lp(a) levels and in the presence of apo E/E3 allele, only Lp(a) levels were determined as risk factors.

CONCLUSION

This study showed that while apoE polymorphism was not a risk factor itself, high Lp(a), LDL-chol and apoB were determined to be risk factors in E3 or E4 carriers.

Genetic polymorphisms for the study of multifactorial stroke

Single-gene disorders explain only a minority of stroke cases. Stroke represents a complex trait, which is usually assumed to be polygenic. On this topic, the role of a wide number of candidate genes has been investigated in stroke through association studies, with controversial results. Therefore, it is difficult for the clinician to establish the validity and the level of clinical applicability of the previously reported associations between genetic factors and stroke. This review is an update and an extensive analysis of the more recent association studies conducted in stroke. We evaluated a number of studies on several candidate genes (including F5, F2, FGA/FGB/FGG, F7, F13A1, vWF, F12, SERPINE1, ITGB3/PLA1/PLA2/ITGA2B, ITGA2, GP1BA, ACE, AGT, NOS3, APOE, LPL, PON1, PDE4D, ALOX5AP, MTHFR, MTR, and CBS), providing a final panel of genes and molecular variants. We categorized this panel in relation to the degree of association with stroke, supported by the results of meta-analyses and case-control studies. Our findings could represent a useful tool to address further molecular investigations and to realize more detailed meta-analyses.

ACE I/D polymorphism in Korean patients with ischemic stroke and silent brain infarction

OBJECTIVES

Angiotensin-converting enzyme (ACE) polymorphism may play a role in stroke and silent brain infarction (SBI) susceptibility, but the results among the populations studied to date have not been consistent. Thus, we investigated the association between ACE genotypes and ischemic stroke and SBI in Korean patients.

SUBJECTS AND METHODS

DNA samples from 237 stroke patients, 264 SBI patients and 234 age-matched controls were amplified using polymerase chain reaction to detect the ACE ins/del (I/D) polymorphism. Genotype was determined by the presence of a 490-bp band (I allele) or a 190-bp band (D allele) in agarose gel electrophoresis.

RESULTS

Odds ratios of the I/D and D/D genotypes and the overall (I/D + D/D) for the I/I genotype were significantly different between stroke patients and normal controls. However, there was no significant difference between patients with SBI and controls.

CONCLUSIONS

This study is the first report of a significant association between ACE polymorphism and ischemic stroke in the Asian population. Although no consistent associations have been found between ACE polymorphism and stroke in the populations studied to date, the ACE polymorphism may be a genetic determinant of ischemic stroke, at least in Korean patients.