Interaction of homocysteine and conventional predisposing factors on risk of ischaemic stroke in young people: consistency in phenotype-disease analysis and genotype-disease analysis

Relationship of Methylenetetrahydrofolate Reductase (MTHFR) C677T Variation With Susceptibility of Patients With Ischemic Stroke: A Meta-Analysis

Discovery and validation of genetic factors for multifactorial and polygenic disorders like stroke are needed to make progress in precision medicine. Although some traditional risk factors for stroke have been identified, they do not fully explain the pathophysiological mechanism of ischemic stroke. The research of genetic risk factors is becoming increasingly relevant in the understanding of stroke mechanisms and the finding of population-specific therapeutic targets. The methylenetetrahydrofolate reductase (MTHFR) gene is involved in homocysteine metabolism, and a high homocysteine level is a risk factor for stroke. Using a meta-analysis technique, we investigated the link between the MTHFR C677T gene polymorphism and the risk of ischemic stroke.

We used the electronic databases PubMed, Medline, Embase, and Google Scholar to find articles in the Journal of Stroke. If heterogeneity was more than 50%, pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using a random-effects model; otherwise, a fixed-effects model was used.

A total of 67 case-control studies with 17,704 cases and 21,981 controls met our inclusion criteria. The Asian population was represented by 41 studies, whereas the Caucasian population was represented by 26. Under the recessive model, a gene polymorphism at the 677 location of the MTHFR gene is related to an elevated risk of ischemic stroke (OR: 1.29, 95% CI: 1.22-1.37, P < 0.001).

People who have the MTHFR C677T gene polymorphism have a greater risk of stroke than people who do not.

Genetic determinants of intracranial large artery stenosis in the northern Manhattan study

BACKGROUND

Intracranial stenosis is one of the most common causes of stroke worldwide. Several single nucleotide polymorphisms have been associated with intracranial atherosclerosis, which is inferred to be the most common underlying cause of intracranial large artery stenosis (ILAS). We previously reviewed known genetic variants related to ILAS in predominantly Asian cohorts, but their prevalence and role in ILAS among western multiethnic populations are uncertain.

METHODS

We leveraged existing imaging and genetic data from the Northern Manhattan Study, a multiethnic prospective cohort study. Based on literature review, we selected adiponectin Q (ADIPOQ) rs2241767 and rs182052, ring finger protein 213 (RNF213) rs112735431, apolipoprotein E (APOE) rs429358, phosphodiesterase 4D (PDE4D) rs2910829, lipoprotein lipase (LPL) rs320, and aldosterone synthase (CYP11B2) rs1799998 variants as candidates to explore. We defined ILAS as luminal stenosis >50% in any intracranial large artery using time-of-flight magnetic resonance angiography (MRA).

RESULTS

We included 1109 participants (mean age 70 ± 9 years, 70% Hispanic, 60% women) in this study. ILAS was identified in 81 (7%) NOMAS participants. Logistic regression analyses adjusted for age, sex, principal components, and vascular risk factors showed ILAS prevalence associated with CYP11B2 rs1799998 under the dominant model (OR = 0.56, 95%CI: 0.35-0.89) and LPL rs320 heterozygote genotype (OR = 1.68, 95%CI: 1.05-2.71). The genotype distributions of ADIPOQ rs2241767 and rs182052, APOE rs429358 and CYP11B2 rs1799998 variants were significantly different among non-Hispanic white and Black, and Hispanic groups. When participants were further stratified by race/ethnicity, the estimates were consistent for CYP11B2 rs1799998 across race/ethnic groups but not for LPL rs320.

CONCLUSION

The CYP11B2 rs1799998 variant may be a protective genetic factor for ILAS across race/ethnic groups, but the risk of ILAS associated with LPL rs320 varies by race/ethnic group. Further functional studies may help elucidate the role that these variants play in the pathophysiology of ILAS.

Prevalence and risk factors for hyperhomocysteinemia: a population-based cross-sectional study from Hunan, China

OBJECTIVES

Hyperhomocysteinemia is an independent risk factor for cardiovascular diseases. We aimed to investigate the prevalence and risk factors for hyperhomocysteinemia, especially modifiable lifestyle factors, such as smoking behaviour and dietary factors.

DESIGN

Population-based cross-sectional study.

SETTING

Hunan Province, China PARTICIPANTS: A total of 4012 participants completed the study, between July 2013 and March 2014. The median age is 55 (interquartile range: 45-63) years, with 1644 males (41%) and 2368 females (59%).

MAIN OUTCOME MEASURES

Homocysteine level were measured by the microplate enzyme immunoassay method. Hyperthomocysteinemia was defined as ≥15 µmol/L. Questionnaire was used to investigate potential risk factors of hyperhomocysteinemia. Crude odd ratio (OR) or adjusted OR with 95% CI were determined by using univariable or multivariable logistic regression models.

RESULTS

The prevalence of hyperhomocysteinemia is 35.4% (45.4% vs 28.5% for men, women, respectively). One-year increase in age is significantly associated with 2% higher risk of hyperhomocysteinemia (OR=1.02, 95% CI: 1.01 to 1.03). One unit increase of BMI is associated with 5% higher risk of hyperhomocysteinemia (OR=1.05, 95% CI: 1.03 to 1.07). Compared with the non-smoker, smoking participants have a 24% higher risk of hyperhomocysteinemia (OR=1.24, 95% CI: 1.006 to 1.53), while the risk for those quitting smoking are not significantly different (OR=1.14, 95% CI: 0.85 to 1.54). compared with those consuming fruit and vegetable at least once every day, those consuming less than once every day had a significantly higher risk of hyperhomocysteinemia (OR=1.29, 95% CI:1.11 to 1.50). In addition, we found there were significant sex interaction with education level or alcohol drinking on the risk of hyperhomocysteinemia (p_interaction <0.05).

CONCLUSIONS

Higher BMI and older age are potential risk factors for hyperhomocysteinemia. Current smoking but not quitting smoking is associated with higher risk of hyperhomocysteinemia. Fruit and vegetable consumption may have protective effect against hyperhomocysteinemia. Alcohol consumption or education level might interact to influence the risk of hyperhomocysteinemia.

Nonbacterial Thrombotic Endocarditis-A Rare Case of Acute Libman-Sacks Endocarditis Complicated by Multiple Cerebral Infarcts: Case Report and Literature Review

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Acute NBTE can be diagnosed on TTE and TEE.

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LSE complicated by multiple coagulopathies may trigger NBTE and cerebral infarcts.

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Screening with TTE is essential in patients with SLE with multiple risk factors.

Characteristics of Cerebral Stroke in the Tibet Autonomous Region of China

It is well known that cerebrovascular disease has become an important cause of adult death and disability. Strikingly, the Tibet Autonomous Region (TAR) ranks on the top in China for the incidence of stroke. To help explain this phenomenon, we have searched for and analyzed stroke-related literature for the TAR in the past 2 decades and have referenced reports from other regions at similar altitudes. This article focuses on epidemiology features, risk factors, and pathogenesis of stroke in the TAR in an effort to generate a better understanding of the characteristics of stroke in this region. The special plateau-related factors such as its high elevation, limited oxygen, the high incidence of hypertension, smoking, and the unique dietary habits of the region are correlated with the high incidence of stroke. In addition to these factors, the pathogenesis of stroke in this high-altitude area is also unique. However, there is no established explanation for the unique occurrence and high incidence of stroke in the TAR. Our study provides an important rationale not only for the clinic to prevent and treat this disease, but also for the government to develop appropriate health policies for the prevention of stroke in the TAR.

Folic Acid Therapy Reduces the First Stroke Risk Associated With Hypercholesterolemia Among Hypertensive Patients

BACKGROUND AND PURPOSE

We sought to determine whether folic acid supplementation can independently reduce the risk of first stroke associated with elevated total cholesterol levels in a subanalysis using data from the CSPPT (China Stroke Primary Prevention Trial), a double-blind, randomized controlled trial.

METHODS

A total of 20 702 hypertensive adults without a history of major cardiovascular disease were randomly assigned to a double-blind daily treatment of an enalapril 10-mg and a folic acid 0.8-mg tablet or an enalapril 10-mg tablet alone. The primary outcome was first stroke.

RESULTS

The median treatment duration was 4.5 years. For participants not receiving folic acid treatment (enalapril-only group), high total cholesterol (≥200 mg/dL) was an independent predictor of first stroke when compared with low total cholesterol (<200 mg/dL; 4.0% versus 2.6%; hazard ratio, 1.52; 95% confidence interval, 1.18-1.97; P=0.001). Folic acid supplementation significantly reduced the risk of first stroke among participants with high total cholesterol (4.0% in the enalapril-only group versus 2.7% in the enalapril-folic acid group; hazard ratio, 0.69; 95% confidence interval, 0.56-0.84; P<0.001; number needed to treat, 78; 95% confidence interval, 52-158), independent of baseline folate levels and other important covariates. By contrast, among participants with low total cholesterol, the risk of stroke was 2.6% in the enalapril-only group versus 2.5% in the enalapril-folic acid group (hazard ratio, 1.00; 95% confidence interval, 0.75-1.30; P=0.982). The effect was greater among participants with elevated total cholesterol (P for interaction=0.024).

CONCLUSIONS

Elevated total cholesterol levels may modify the benefits of folic acid therapy on first stroke. Folic acid supplementation reduced the risk of first stroke associated with elevated total cholesterol by 31% among hypertensive adults without a history of major cardiovascular diseases.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00794885.

Vascular risk factors aggravate cognitive impairment in first-ever young ischaemic stroke patients

BACKGROUND AND PURPOSE

Young ischaemic stroke patients often suffer from cognitive impairment after stroke. However, the risk factors of cognitive impairment are still unclear. This study examined the impact of vascular risk factors (VRFs) on cognitive impairment in first-ever young ischaemic stroke patients.

METHODS

Subjects were divided into low (0-1 VRF, n = 27), medium (2-3 VRFs, n = 45) and high-risk (≥4 VRFs, n = 12) groups according to their number of VRFs. The following VRFs were collected: hypertension, diabetes mellitus, dyslipidaemia, atrial fibrillation, obesity, smoking, excess alcohol consumption, coronary heart disease and hyperhomocysteinaemia. A battery of cognitive assessments was executed 2 weeks after stroke. Differences of cognitive performances between groups were compared. The correlation between VRFs and cognitive function was investigated with an emphasis on discovering the main VRFs.

RESULTS

Eighty-four patients were enrolled in this study eventually. Compared with the low-risk group, the high-risk group had significantly worse performance in most of the cognitive domains. VRFs had a correlation with general cognition, executive function, attention and verbal fluency. After adjusting the covariates, VRFs showed a linear correlation with global cognitive function (R = 0.640, P = 0.000), verbal fluency (R = 0.372, P = 0.000), delayed memory (R = 0.327, P = 0.002), visual attention (R = 0.290, P = 0.007) and executive function (R = 0.266, P = 0.015). Amongst all the VRFs, hypertension, hyperlipidaemia, smoking and hyperhomocysteinaemia were the main influencing VRFs.

CONCLUSION

Vascular risk factors aggravate cognitive impairment after young ischaemic stroke. Effective management of VRFs in young adults is urgent and this may reduce the cognitive impairment.

Quantitative assessment of association between rs1801133 polymorphism and susceptibility to stroke

Methylenetetrahydrofolate reductase (MTHFR) is an important enzyme involved in folate metabolism, which is essential for DNA synthesis and methylation. Genetic variations in the MTHFR gene seem to contribute to a decreased activity of MTHFR, ultimately confer increased susceptibility to stroke. To assess the association between this polymorphism and stroke risk, we conducted a comprehensive meta-analysis based on 73 eligible studies. A total of 73 studies, including 10,225 cases and 13,800 controls identified between 1999 and 2012, were selected through researching the PubMed, MEDLINE, EMBASE, Cochrane Library, Web of Science, and Chinese Biomedical Chinese National Knowledge Infrastructure and Literature database databases. Odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were used to assess the association. Overall, a significant elevated risk of stroke risk was associated with the rs1801133 polymorphism in all genetic models (homozygote model: OR 1.296, 95% CI 1.109-1.514; dominant model: OR 1.179, 95% CI 1.058-1.315; recessive model: OR 1.209, 95% CI 1.063-1.375; allele comparison model: OR 1.154, 95% CI 1.061-1.256). In the stratified analyses, significantly increased stroke risks were indicated among Asians in all genetic models (homozygote model: OR 1.726, 95% CI 1.314-2.267; dominant model: OR 1.535, 95% CI 1.282-1.838; recessive model: OR 1.452, 95% CI 1.160-1.818; allele comparison model: OR 1.403, 95% CI 1.211-1.626).The present meta-analysis suggests that rs1801133 polymorphism contributes to the risk of stroke, of note, in Asian populations.

The Association Between Cervical Spine Manipulation and Carotid Artery Dissection: A Systematic Review of the Literature

OBJECTIVE

Controversy surrounds the safety of cervical spine manipulation. Ischemic stroke secondary to cervical spine manipulation is a hypothesized adverse event. In Canada, the seriousness of these events and their perceived association to cervical spine manipulation has led some members of the public to call for a ban of the procedure. The primary objective of this study was to determine the incidence of internal carotid artery (ICA) dissection after cervical spine manipulation in patients who experience neck pain and its associated disorders. The secondary objective was to determine whether cervical spine manipulation is associated with an increased risk of ICA dissection in patients with neck pain, upper back pain, or headaches.

METHODS

We systematically searched MEDLINE, CINAHL, Alternative Health, AMED, Index to Chiropractic Literature, and EMBASE from 1970 to November 2012. Two independent reviewers used standardized criteria to screen the eligibility of articles. We considered cohort studies, case-control studies, and randomized clinical trials that addressed our objectives. We planned to critically appraise eligible articles using the Scottish Intercollegiate Guideline Network methodology.

RESULTS

We did not find any epidemiologic studies that measured the incidence of cervical spine manipulation and ICA dissection. Similarly, we did not find any studies that determined whether cervical spine manipulation is associated with ICA dissection.

CONCLUSIONS

The incidence of ICA dissection after cervical spine manipulation is unknown. The relative risk of ICA dissection after cervical spine manipulation compared with other health care interventions for neck pain, back pain, or headache is also unknown. Although several case reports and case series raise the hypothesis of an association, we found no epidemiologic studies that validate this hypothesis.

Effect of folic acid intervention on the change of serum folate level in hypertensive Chinese adults: do methylenetetrahydrofolate reductase and methionine synthase gene polymorphisms affect therapeutic responses?

OBJECTIVES

To assess the influence of individual methylenetetrahydrofolate reductase (MTHFR) C677T and methionine synthase A2756G polymorphisms on the change of serum folate concentration in response to different dosages and durations of folic acid (FA) supplementation in hypertensive Chinese adults.

METHODS

A total of 480 patients with mild or moderate essential hypertension were randomly assigned to three treatment groups: (a) enalapril only (10 mg, control group); (b) enalapril FA tablet [10 : 0.4 mg (10 mg of enalapril combined with 0.4 mg of FA), low-FA group]; (c) enalapril FA tablet (10 : 0.8 mg, high-FA group), once daily for 8 weeks. Individual serum folate levels were measured at baseline, and at 4 and 8 weeks posttreatment.

RESULTS

After 4 or 8 weeks of treatment, increases in serum folate were seen across all genotypes and FA dosage groups. However, compared with patients with 677CC genotype, those with CT or TT genotype in the low-FA group and TT genotype in the high-FA group still had significantly lower folate concentrations, particularly women. In the low-FA group, patients with CT or TT genotype showed an attenuated response compared with those with CC genotype (median ratio of folate at week 8 to that at baseline: CC,1.953 vs. CT,1.755 or TT,1.637, P<0.01 for both). Such an attenuated response was not observed in the high-FA group. Yet, only in the high-FA group did serum folate appear to reach a plateau after 4 weeks of treatment in all three MTHFR 677 genotypes and the methionine synthase 2756 AG/GG genotype.

CONCLUSION

We demonstrated that MTHFR C677T polymorphisms can not only affect serum folate levels at the baseline and post-FA treatment, but also therapeutic responses to various dosages and durations of FA supplementation.

Prevalence of hyperhomocysteinaemia and its major determinants in rural Chinese hypertensive patients aged 45–75 years

We aimed to investigate the prevalence of hyperhomocysteinaemia (total plasma homocysteine (tHcy) ≥ 10 μmol/l) and its major determinants in rural Chinese hypertensive patients. A cross-sectional investigation was carried out in Lianyungang of Jiangsu province, China. This analysis included 13 946 hypertensive adults. The prevalence of hyperhomocysteinaemia was 51·6 % (42·7 % in women and 65·6 % in men). The OR of hyperhomocysteinaemia were 1·52 (95 % CI 1·39, 1·67) and 2·32 (95 % CI 2·07, 2·61) for participants aged 55–65 and 65–75 v. 45–55 years; 1·27 (95 % CI 1·18, 1·37) for participants with a BMI ≥ 25 v. < 25 kg/m2; 1·14 (95 % CI 1·06, 1·23) for participants with v. without antihypertensive treatment; 1·09 (95 % CI 1·00, 1·18) for residents inland v. coastal; 0·89 (95 % CI 0·82, 0·97) and 0·83 (95 % CI 0·74, 0·92) for participants with moderate and high v. low physical activity levels; 1·54 (95 % CI 1·41, 1·68) and 2·47 (95 % CI 2·17, 2·81) for participants with a glomerular filtration rate 60–90 and < 60 v. ≥ 90 ml/min per 1·73 m2; and 1·20 (95 % CI 1·07, 1·35) and 3·81 (95 % CI 3·33, 4·36) for participants with CT and TT v. CC genotype at methylenetetrahydrofolate reductase 677C>T polymorphism, respectively. Furthermore, higher tHcy concentrations were observed in smokers of both sexes (men: geometric mean 12·1 (interquartile range (IQR) 9·2–14·5) v. 11·9 (IQR 9·3–14·0) μmol/l, P= 0·005; women: geometric mean 10·3 (IQR 8·3–13·0) v. 9·6 (IQR 7·8–11·6) μmol/l, P= 0·010), and only in males with hypertension grade 3 (v. grade 1 or controlled blood pressure) (geometric mean 12·1 (IQR 9·2–14·4) v. 11·7 (IQR 9·2–14·0), P= 0·016) and in male non-drinkers (yes v. no) (geometric mean 12·3 (IQR 9·4–14·8) v. 11·7 (IQR 9·1–13·9), P= 0·014). In conclusion, there was a high prevalence of hyperhomocysteinaemia in Chinese hypertensive adults, particularly in the inlanders, who may benefit greatly from tHcy-lowering strategies, such as folic acid supplementation and lifestyle change.

Risk factors and treatment of stroke in Chinese young adults

OBJECTIVE

To evaluate the risk factors and treatment status of Chinese stroke patients aged 35-45 years old.

METHODS

We collected data from 1988 in-hospital stroke patients aged 35-45 years old from 36 hospitals in mainland China and compared it to 12,260 health controls with the same age. Information about stroke risk factors was obtained through a questionnaire. Multiple logistic regression and chi-square test were performed to explore the association between risk factors and stroke in young patients.

RESULTS

Of the stroke patients, 94.3% had an ischemic stroke and 73.0% were male. Frequencies of stroke risk factors were significantly higher in patients than those in controls, including history of hypertension (41.0% versus 9.0%, p<0.05), diabetes (5.2% versus 1.7%, p<0.05), hypercholesterolemia (4.2% versus 2.9%, p<0.05), heart diseases (7.2% versus 1.6%, p<0.05), stroke (14.9% versus 1.3%, p<0.05), smoking (38.8% versus 33.3%, p<0.05) and drinking (38.0% versus 24.9%, p<0.05). Furthermore, only 12.8% of patients with hypertension took antihypertensive drugs regularly, and 27.9% of diabetic patients took hypoglycemic drugs regularly. Risk factors when compared between male and female patients were as follows: history of heart diseases (5.9 versus 10.8, p<0.05), smoking (50.9 versus 6.5, p<0.05) and drinking (50.4 versus 5.8, p<0.05).

CONCLUSION

Majority of the Chinese stroke patients aged 35-45 years were male and had suffered an ischemic stroke. The history of stroke, heart disease and hypercholesterolemia could increase the risk of stroke in young adults, and the risk factors in the order of importance were hypertension, smoking, alcohol drinking, previous stroke, heart disease, diabetes mellitus and hyperlipidemia. Hypertension, smoking and alcohol drinking were found to be the main risk factors; treatment state and lifestyle should be improved for young stroke patients.

The combination of homozygous MTHFR 677T and angiotensin II type-1 receptor 1166C variants confers the risk of small-vessel-associated ischemic stroke

Previous studies have suggested that both angiotensin II type-1 receptor (AT1R) 1166C and methylenetetrahydrofolate reductase (MTHFR) 677T variants can have disadvantageous effects on the small-vessel circulation under certain conditions. The purpose of this study was to analyze the possible consequences of the simultaneous distribution of these two genetic variants in different types of ischemic stroke. The genetic and clinical data on 357 ischemic stroke patients and 263 control subjects were analyzed by using univariate and logistic statistical approaches. Neither the MTHFR 677T nor the AT1R 1166C genetic variant alone conferred the risk of any subtype of ischemic stroke. The combination of the homozygous MTHFR 677TT genotype and at least one AT1R 1166C allele occurred more frequently in the ischemic stroke patients (8.68%) than in the controls (4.56%, p < 0.05). Specific subclassification of the patients revealed an accumulation of this combination in small-vessel-associated ischemic stroke (12.2%, p < 0.01); multivariate logistic regression analysis of the data confirmed this association, with an odds ratio of 2.66 (95% confidence interval, 1.28-7.89; p < 0.05). These findings suggest that the combination of these two genetic factors can contribute to the development of small-vessel cerebral infarcts. Although the exact mechanism of action is not known, addition of the unfavourable effects on the endothelial function can be presumed.

MTHFR 677 TT genotype and hyperhomocysteinaemia: an underestimated risk TANDEM for patients with stroke

Synergy between hyperhomocysteinaemia and conventional risk factors for stroke