Common mutations at the homocysteine metabolism pathway and pediatric stroke

Association of methylenetetrahydrofolate reductase (MTHFR) rs1801133 (677C>T) gene polymorphism with ischemic stroke risk in different populations: An updated meta-analysis

Background: Recently, increasing evidence has implicated methylenetetrahydrofolate reductase (MTHFR) gene mutation as a risk factor for ischemic stroke (IS) in the general population. However, studies have been inconclusive and lack evidence on specific populations. We aim to determine whether the rs1801133 (NC_000001.11 (MTHFR):g. 677C>T (p.Ala222Val) variant, we termed as MTHFR rs1801133 (677 C>T), is linked to an increased risk of IS in different age groups and ancestry groups. Methods: The literature relevant to our study was found by searching the PubMed, Cochrane Library, Web of Science, EMBASE, and CNKI databases. A random effect model analysis was used to calculate the pooled odds ratio (OR) and 95% confidence interval (CI) to evaluate any possible association. We conducted a subgroup analysis based on the age and ancestry groups of the included populations. Results: As of March 2022, 1,925 citations had been identified in electronic databases, of which 96 studies involving 34,814 subjects met our eligibility criteria. A strong link was found between IS and the MTHFR gene rs1801133 (677C>T) polymorphism in all genetic models [dominant genetic model (OR = 1.47; 95%CI = 1.33-1.61; p < 0.001), recessive genetic model (OR = 1.52; 95%CI = 1.36-1.71; p < 0.001), heterozygous model (OR = 1.36; 95%CI = 1.24-1.48; p < 0.001), homozygous model (OR = 1.82; 95%CI = 1.58-2.11; p < 0.001), and T allelic genetic model (OR = 1.37; 95%CI = 1.27-1.48; p < 0.001)]. Further subgroup analyses indicated that the MTHFR rs1801133 (677C>T) variant may increase the risk of IS in Asian, Hispanic, or Latin population, middle-aged, and elderly populations (p < 0.001). Conclusion: Our results implied that mutation of the T allele of MTHFR rs1801133 (677C>T) could be a risk factor for IS. A significant association was found among Asian, Hispanic, or Latin population, middle-aged, and elderly people.

The Genetic Basis of Strokes in Pediatric Populations and Insight into New Therapeutic Options

Strokes within pediatric populations are considered to be the 10th leading cause of death in the United States of America, with over half of such events occurring in children younger than one year of life. The multifactorial etiopathology that has an influence on stroke development and occurrence signify the importance of the timely recognition of both modifiable and non-modifiable factors for adequate diagnostic and treatment approaches. The early recognition of a stroke and stroke risk in children has the potential to advance the application of neuroprotective, thrombolytic, and antithrombotic interventions and rehabilitation strategies to the earliest possible timepoints after the onset of a stroke, improving the outcomes and quality of life for affected children and their families. The recent development of molecular genetic methods has greatly facilitated the analysis and diagnosis of single-gene disorders. In this review, the most significant single gene disorders associated with pediatric stroke are presented, along with specific therapeutic options whenever they exist. Besides monogenic disorders that may present with stroke as a first symptom, genetic polymorphisms may contribute to the risk of pediatric and perinatal stroke. The most frequently studied genetic risk factors are several common polymorphisms in genes associated with thrombophilia; these genes code for proteins that are part of the coagulation cascade, fibrolysis, homocystein metabolism, lipid metabolism, or platelets. Single polymorphism frequencies may not be sufficient to completely explain the stroke causality and an analysis of several genotype combinations is a more promising approach. The recent steps forward in our understanding of the disorders underlying strokes has given us a next generation of therapeutics and therapeutic targets by which to improve stroke survival, protect or rebuild neuronal connections in the brain, and enhance neural function. Advances in DNA sequencing and the development of new tools to correct human gene mutations have brought genetic analysis and gene therapy into the focus of investigations for new therapeutic options for stroke patients.

Homocysteine metabolism as the target for predictive medical approach, disease prevention, prognosis, and treatments tailored to the person

Homocysteine (Hcy) metabolism is crucial for regulating methionine availability, protein homeostasis, and DNA-methylation presenting, therefore, key pathways in post-genomic and epigenetic regulation mechanisms. Consequently, impaired Hcy metabolism leading to elevated concentrations of Hcy in the blood plasma (hyperhomocysteinemia) is linked to the overproduction of free radicals, induced oxidative stress, mitochondrial impairments, systemic inflammation and increased risks of eye disorders, coronary artery diseases, atherosclerosis, myocardial infarction, ischemic stroke, thrombotic events, cancer development and progression, osteoporosis, neurodegenerative disorders, pregnancy complications, delayed healing processes, and poor COVID-19 outcomes, among others. This review focuses on the homocysteine metabolism impairments relevant for various pathological conditions. Innovative strategies in the framework of 3P medicine consider Hcy metabolic pathways as the specific target for in vitro diagnostics, predictive medical approaches, cost-effective preventive measures, and optimized treatments tailored to the individualized patient profiles in primary, secondary, and tertiary care.

MTHFR A1298C gene polymorphism on stroke risk: an updated meta-analysis

Background

Previous studies have shown the effect of MTHFR A1298C gene polymorphism on stroke risk. But the results of published studies remained inconclusive and controversial. So we conducted a meta-analysis to accurately estimate the potential association between MTHFR A1298C gene polymorphism and stroke susceptibility.

Methods

A systematic literature search on Embase, Pubmed, Web of Science, Cochrane Library, China National Knowledge Infrastructure (CNKI) and WanFang electronic database identified 40 articles including 5725 cases and 8655 controls. Strength of association was evaluated by pooled odds ratio (OR), 95% confidence interval (CI) and p value. Funnel plots and Begger’s regression test were applied for testing the publication bias. Statistical analysis of all data was performed by Stata 12.0.

Results

The meta-analysis results indicated a significant relationship between MTHFR gene A1298C polymorphisms and stoke risk under the C allelic genetic model (OR = 1.19, 95%CI = 1.07–1.32, p = 0.001), dominant genetic model (OR = 1.19, 95%CI = 1.06–1.33, p = 0.004) and recessive genetic model (OR = 1.43, 95%CI =1.15–1.77, p = 0.001). In subgroup analysis, we discovered obvious correlation in three genetic model of Asian, stroke type, adult by ethnicity, population, stroke type, source of control and case size. Additionally, in studies of control from hospital and case size equal 100, obvious correlation was also found in the three genetic model.

Conclusions

Our meta-analysis results indicated that there was evidence to support the correlation between MTHFR A1298C polymorphism and stroke susceptibility, especially in adults and ischemic stroke.

Arterial Ischemic Stroke-Peculiarities of Clinical Presentation and Risk Factors in Indian Children

There are not enough recent studies on arterial ischemic stroke (AIS) in Indian children. We retrospectively reviewed data on 95 children (69 boys), aged 3 months to 17 years, with AIS. Focal signs were noted in 84 (88%) with hemiparesis in 72 (76%). Diffuse signs were present in 33 (35%) with fever in 22 (23%), altered mental status in 20 (21%), and headache in 12 (13%). Seizures occurred in 29 (31%) children. Arteriopathy was observed in 57 (60%) children with mineralizing lenticulostriate vasculopathy (mLSV) in 22 (23%) being the most common, followed by moyamoya in 14 (15%), arterial dissection in 9 (10%), and focal cerebral arteriopathy (FCA) in 8 (8%). Preceding head/neck trauma was present in 27 (28%) children: 23 had minor head trauma (MHT), 3 neck trauma, and 1 unspecified. Other common risk factors (RFs) were iron deficiency in 10 children, homocysteinemia in 8 children, and tuberculous meningitis in 5 children. Complete or nearly complete recovery occurred in 42 (44%). Nine children developed epilepsy and five cognitive and language disability. Stroke recurrences occurred in nine children. Overall, arteriopathies accounted for majority of the cases of childhood AIS in our study with mLSV and moyamoya being the most frequent. Compared with data from Western countries, FCAs, postvaricella arteriopathy, and arterial dissections were less common. Of the nonarteriopathic RFs, MHT, iron deficiency, homocysteinemia, and neuroinfections were most frequent in our cohort in contrast to cardioembolic diseases and inherited procoagulant conditions, which are common in developed countries.

Relationship between methylenetetrahydrofolate reductase (MTHFR) gene (A1298C) polymorphism with the risk of stroke: A systematic review and meta-analysis

Studies on relationship between methylenetetrahydrofolate reductase gene (MTHFR) gene A1298C polymorphism with the risk of ischemic as well as hemorrhagic stroke have shown discordant results. Present meta-analysis was aimed to clarify the relationship between MTHFR gene A1298C polymorphism with risk of stroke. A comprehensive literature search for all published articles was performed in electronic database including PubMed, EMbase, Cochrane Library, Trip Databases, Worldwide Science, CINAHL, and Google Scholar up to 31st  December 2019. Pooled odds ratio (ORs) with 95% confidence interval (CIs) under dominant, recessive, and allelic models was calculated. Sensitivity analysis was also performed to detect the heterogeneity. In our meta-analysis, a total of 20 studies with 19 case control studies involving 2871 ischemic stroke (IS) cases and 3984 controls and 3 studies with 201 hemorrhagic stroke cases and 1349 controls were included. Our findings suggest that there was a significant relationship between MTHFR gene A1298C gene polymorphism with risk of ischemic stroke (dominant model: OR = 1.32, 95% CI = 1.06-1.66, recessive model: OR = 1.45, 95% CI = 1.06-1.99 and allelic model: OR = 1.35, 95% CI = 1.00-1.84, respectively). However, no significant relationship between MTHFR gene A1298C gene polymorphism with the risk of hemorrhagic stroke. Findings of this meta-analysis concludes that MTHFR gene A1298 C polymorphism could be capable of increasing stroke susceptibility in Asian, but not in Caucasian population. Genotyping of MTHFR gene A1298C polymorphism may be used as a predictor for the occurrence of ischemic stroke.

Cerebral Sinus Venous Thrombosis and Prothrombotic Risk Factors in Children: A Single-Center Experience From Turkey

BACKGROUND

Cerebral sinus venous thrombosis (CSVT) is a rare cerebrovascular disease that may be life-threatening, especially in children.

OBJECTIVE

The purpose of this study was to assess the clinical presentation, radiologic imaging, underlying conditions, treatment, and outcomes of children with CSVT.

PATIENTS AND METHODS

In total, 23 consecutive children aged between 1 month to 18 years with CSVT, who were followed-up in Erciyes University Children's Hospital, were retrospectively enrolled in the study from January 2000 to December 2016.

RESULTS

The median age of the 23 children (13 female patients, 10 male patients) at initial diagnosis was 60 months (1 to 204 mo). The most common clinical manifestation was headache/irritability (n=9). The most common site of the CSVT was the transverse sinus (n=16). The most common prothrombotic risk factor was protein C deficiency (n=4). Underlying risk factors were detected in 15 patients. Genetic risk factors such as protein C deficiency, infections, trauma, malignancies, autoimmune hemolytic anemia, neurometabolic disorders, asphyxia, and cardiac malformations were common risk factors. Six children died. Multiple sinus involvement and parenchymal hemorrhages were seen in 4 and in 3 of the 6 children who died, respectively.

CONCLUSIONS

Protein C deficiency seemed to be relatively high in the presented children. Multiple sinus involvement and additional parenchymal hemorrhages represent poor prognostic features.

Is the 1298A>C polymorphism in the MTHFR gene a risk factor for arterial ischaemic stroke in children? The results of meta-analysis

An elevated level of homocysteine is a risk factor for vascular diseases, brain atrophy and several other disorders. The 1298A>C polymorphism (rs1801131) leads to mildly decreased MTHFR activity. Previously, it was observed that the MTHFR 1298A>C polymorphism in combined analysis with the MTHFR 677C>T polymorphism increases homocysteine levels. However, conflicting results on its relation to ischaemic stroke in children can be found. We conducted a meta-analysis to analyse possible connections between the MTHFR 1298A>C polymorphism and ischaemic stroke in paediatric patients. We identified available data published before December 2016 using appropriate keywords and searching PubMed as well as the references cited in the found articles. Eight case-control studies were included in the meta-analysis (426 children with stroke and 778 controls). Statistical analyses were made using R and Comprehensive Meta-Analysis softwares to investigate the impact of polymorphism in four models: dominant, recessive, additive and allelic. No publication bias was observed in the meta-analysis. We demonstrated no relationship between the 1298A>C polymorphism and ischaemic stroke in children in the case of recessive, additive and allelic models. However, the results of the dominant model analysis should be treated with caution due to the sensitivity analysis results. After omitting one of the included study, we observed a significant association between the carriers of the MTHFR C allele (cases with AC + CC genotypes) and ischaemic stroke in children (OR 1.35 95% CI 1.02-1.79, p = 0.035 in a fixed effects model). In conclusion, the 1298A>C polymorphism in the MTHFR gene is not a risk factor for ischaemic stroke in paediatric patients.

Influence of Folate-Related Gene Polymorphisms on High-Dose Methotrexate-Related Toxicity and Prognosis in Turkish Children with Acute Lymphoblastic Leukemia

OBJECTIVE

High-dose methotrexate (HD-MTX) is widely used in the consolidation phase of childhood acute lymphoblastic leukemia (ALL), but the roles that polymorphisms in folate-related genes (FRGs) play in HD-MTX toxicity and prognosis in children with ALL are not understood. The aims of this study were to investigate the frequencies of polymorphisms in the genes for thymidylate synthase (TS), methionine synthase reductase (MTRR), and methylene tetrahydrofolate reductase (MTHFR) in Turkish children with ALL and to assess associations between these polymorphisms and HD-MTX-related toxicity and leukemia prognosis in this patient group.

MATERIALS AND METHODS

FRG polymorphisms were assessed by real-time polymerase chain reaction. Survival status, MTX levels, and toxicity data were retrieved from 106 patients' charts.

RESULTS

The allele frequencies for the FRG polymorphisms were as follows: TS 2R 41.0%, 3R 57.0%, and 4R 2.0%; MTRR 66A 42.4% and 66G 57.6%; MTHFR 677C 59.3% and 677T 40.7%; and MTHFR 1298A 58.1% and 1298C 41.9%. At the 48th hour of HD-MTX infusion, serum MTX was significantly higher in patients who had TS 2R/3R/4R variants as compared to those with wild-type TS (p<0.05). No significant differences were detected with respect to event-free survival or toxicity between wild-type and other FRG variants.

CONCLUSION

The frequencies of FRG polymorphisms in Turkish children with ALL are similar to those reported in other Caucasian populations. This is the first published finding of the TS 3R/4R variant in the Turkish population. The results indicate that HD-MTX can be tolerated by leukemic children with some polymorphic variants of FRG; thus, it may prevent future risk of leukemic relapse.

An extremely rare complication following frontoorbital advancement: infarction of the recurrent artery of Heubner

Many intracranial as well as extracranial complications can be seen following craniosynostosis surgeries. In this article, we would like to share an extremely rare complication of the infarction of the recurrent artery of Heubner, occurred following frontoorbital advancement. In this case, an 18-month-old male patient underwent supraorbital bar and frontal bone remodeling surgery for nonsyndromic metopic suture synostosis. The preoperative neurosurgical evaluation revealed no signs of increased intracranial pressure. On the 3rd postoperative day, the patient developed asymmetric smile and weakness on the left extremities. Computerized tomography showed a hypodense infarction region around the right basal ganglia and internal capsule, concordant with the region supplied by the recurrent artery of Heubner. The patient's symptoms started to regress on the 2nd day of enoxaparine treatment and he was discharged on 12th postoperative day with almost no signs of the event. In this paper, we presented an unlikely complication after frontoorbital advancement. Keeping in mind the long operating time and the proximity of the procedure to the central nervous system, assessment of the neurological function of the patients both before and after the operation and rapid intervention in case of development of neurologic symptoms are of great importance.

Association of Polymorphisms in Coagulation Factor Genes and Enzymes of Homocysteine Metabolism With Arterial Ischemic Stroke in Children

Despite the identification of a wide range of inherited and acquired risk factors for arterial ischemic stroke (AIS) in children, genetic risk factors are incompletely characterized and may vary among different populations. We investigated the role of individual and combined inherited prothrombotic and intermediate-risk factors in 73 children with perinatal (n = 35) and childhood AIS (n = 38) and 100 age- and sex-matched controls. Ten polymorphisms in 8 candidate genes encoding coagulation and fibrinolytic proteins (factor V [FV] Leiden, FV HR2, factor II [FII] G20210A, β-fibrinogen [β-FBG]-455G>A, factor XIII [FXIII]-A p.Val34Leu, plasminogen activator inhibitor 1 4G/5G), homocysteine metabolism (methylenetetrahydrofolate reductase [MTHFR] C677T, MTHFR A1298C), and intermediate-risk factors (angiotensin-converting enzyme I/D, apoE ∊2-4) were detected using a multilocus genotyping assay. Allele-specific polymerase chain reaction was used for the determination of human platelet alloantigens (HPA-1, HPA-2, HPA-3, and HPA-5). Factor V Leiden was associated with an increased risk of AIS (odds ratio [OR]: 4.72, 95% confidence interval [CI]: 1.22-18.27) and perinatal AIS (OR: 8.29, 95% CI: 1.95-35.24). Human platelet antigen-3b allele carriers had a 2-fold lower risk of AIS (OR: 0.51, 95% CI: 0.26-0.98) and perinatal AIS (OR: 0.40, 95% CI: 0.18-0.92). A 2.21-fold increased risk of childhood AIS (95% CI: 1.03-4.73) was identified in FXIII-A Leu34 allele carriers. Combined FV Leiden/FV HR2, FV Leiden/MTHFR A1298C, FV Leiden/MTHFR C677T/MTHFR A1298C, and FV Leiden/FV HR2/MTHFR A1298C heterozygosity was identified in children with AIS but not in controls, which revealed a statistically significant difference. This case-control study shows that besides already documented association between FV Leiden and AIS, other previously unreported polymorphisms (FXIII-A p.Val34Leu, HPA-3) and several genotype combinations that always include heterozygous FV Leiden can be related to AIS in Croatian population.

Sequence variants on chromosome 9p21 are associated with ischemic stroke and the lipids level in Chinese Han population

BACKGROUND

Several studies have demonstrated that variants on chromosome 9p21 confer susceptibility to ischemic stroke (IS) disease. But, the results of variants' roles in Chinese IS population are blank or inconsistent.

METHODS

We performed a case-control analysis in 116 patients with IS and 118 non-IS controls of Han background to determine whether 4 single nucleotide polymorphisms were associated with IS. DNA was extracted from saliva using a magnetic nanoparticles-based method.

RESULTS

After we adjusted for clinical parameters, we found that the rs10757278-GG genotype conveyed 1.88-fold (95% confidence interval [CI], 1.1-3.1; P = .015), the rs1537378-C allele conveyed 2.0-fold (95% CI, 1.2-3.5; P = .008), and the rs1333047-TT genotype conveyed 1.64-fold (95% CI, 1.02-2.6; P = .041) increased risk of IS, respectively. In addition, there is a significant difference of the lipids level between GG genotype compared with that of AA genotype in rs10757278 (P < .05).

CONCLUSIONS

This study is the first one to demonstrate that the rs10757278-GG genotype, the rs1537378-C allele, and rs1333047-TT genotype are associated with IS in Chinese Han populations. More importantly, the variant of rs10757278 may have different degrees of influence on lipids level.

Systematic review: hereditary thrombophilia associated to pediatric strokes and cerebral palsy

OBJECTIVES

This review aimed to organize and consolidate the latest knowledge about mutations and genetic polymorphisms related to hereditary thrombophilia and their potential association with pediatric stroke and cerebral palsy (CP).

SOURCES

Scientific articles published from 1993 to 2013, written in Portuguese, English, French, and Spanish, were selected and reviewed. The publications were searched in electronic databases, and also in the collections of local libraries. The terms "hereditary thrombophilia", "polymorphisms", "mutation", "pediatric strokes", and "cerebral palsy" were used for the research.

SUMMARY OF THE FINDINGS

The search in databases and in the bibliographic references retrieved 75 articles for inclusion in this review. Studies that investigated hereditary thrombophilias and their associations to CP and arterial and venous pediatric stroke presented contradictory results. The meta-analysis and case-control studies that showed positive results for this association described only slightly increased relative risks and sometimes had questionable conclusions. The association of two or more hereditary thrombophilias, or the association between thrombophilia and other specific clinical risk factors, suggest a higher risk of CP and pediatric stroke than isolated hereditary thrombophilia.

CONCLUSIONS

Larger, multicenter studies should be developed in order to elucidate the role of mutations leading to hereditary thrombophilia and the development of CP and pediatric stroke. The complex and multifactorial etiology of CP and stroke makes this an arduous and difficult task; however, the benefits generated by these studies are immeasurable.

Methylenetetrahydrofolate reductase gene A1298C polymorphism in pediatric stroke--case-control and family-based study

Moderate hyperhomocysteinemia is one of the risk factors of pediatric stroke. Methylenetetrahydrofolate reductase (MTHFR) is an important enzyme, which regulates homocysteine metabolism, and some polymorphisms of gene encoding this enzyme are associated with a decreased activity of the enzyme. The aim of the study was to assess an association between the A1298C polymorphism and pediatric stroke. We also evaluated a possible synergistic effect of A1298C and C677T polymorphisms of this gene. The study group consisted of 88 children after ischemic stroke, 142 of their parents and 111 controls. The A1298C polymorphism was genotyped using the restriction fragment length polymorphism method. We used 2 study designs: a case-control model and a family-based association test. The Statistica 7.1 and EpiInfo 6 softwares were used in all analyses. We did not observe any statistically significant differences either in the transmission of the A allele in the family-based test or in the frequency of the A allele in the patients group compared with the controls. We also did not notice any significant additive or synergistic effects between the A1298C and C677T polymorphisms. An analysis of the results obtained in this study and a critical review of previously published studies indicate that the A1298C polymorphism of the MTHFR gene is not related to ischemic stroke in children.

Childhood stroke: results of 130 children from a reference center in Central Anatolia, Turkey

BACKGROUND

Although stroke among children is rare, it can cause significant morbidity and mortality. We aim to share our experience of children with arterial ischemic stroke.

METHODS

The initial symptoms, demographical features, risk factors, neurological examination, neuroradiological findings, and clinical follow-up data of 130 Turkish children seen between 2002 and 2013 were retrospectively analyzed.

RESULTS

Sixty-eight patients were male. Thirty of the children were aged from 1 to 12 months (seven of them died in this period). Focal neurological signs were the most common presentation, and hemiplegia or hemiparesis were the most common focal signs. Underlying risk factors were detected in 103 patients. Infections and congenital heart disease were the most common risk factors. Seven of the nine children with recurrent arterial ischemic strokes had one or more underlying diseases (moyamoya disease in two children along with factor V Leiden mutation, tuberculous meningitis, congenital heart disease, homocystinuria, and hemiconvulsion-hemiplegia-epilepsy syndrome). The arterial ischemic stroke was located in the middle cerebral circulation in 68 (36 left and 32 right) and in the posterior cerebral artery in 41. Eighteen children died. The neurological outcome was assessed in 98 children. Of these children, 66 children have neurological deficits and 52 children have seizures. Stroke in the first year of life is more often fatal. Recurrent stroke is associated with poor prognosis.

CONCLUSION

Tuberculous meningitis is still a risk factor for arterial ischemic stroke in Turkey. Arterial ischemic stroke in the first year of life and recurrent arterial ischemic stroke represent poor prognostic features.

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.

Methylenetetrahydrofolate reductase (C677T and A1298C) polymorphisms, hyperhomocysteinemia, and ischemic stroke in Tunisian patients

OBJECTIVE

The present study evaluated the role of the methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C gene polymorphisms and correlated these results with plasma homocysteine (Hcy) levels in Tunisian ischemic stroke (IS) patients.

METHODS

Overall, 84 patients with IS were included and compared with 100 healthy controls. The most common stroke risk factors were investigated. Fasting plasma Hcy levels were measured. Genotyping of the MTHFR C677T and A1298 polymorphisms was studied by polymerase chain reaction.

RESULTS

Aside from tobacco and alcohol use, the other studied factors were significant risk factors for IS. Mean plasma Hcy levels were significantly higher in IS patients than in controls (16.1 ± 8.28 μmol/L versus 8.76 ± 3.48 μmol/L, P < 10(-3)). Significant associations were found with both the MTHFR 677(CT + TT) and 1298 (AC + CC) genotypes in comparison with controls (P < 10(-3)). A significant synergistic interaction was also found with the double heterozygote MTHFR 677CT/1298AC (P < 10(-3)). Homocysteine levels were significantly higher in IS patients with the MTHFR C677T variant (CT and TT genotypes) (P < 10(-3)); however, the difference was not significant with the MTHFR A1298C variant (AC and CC genotypes) (P = .31).

CONCLUSION

The MTHFR C677T and A1298 polymorphisms (individually or in concert) and hyperhomocysteinemia represent important risk factors for IS. Elevated Hcy levels were found to be associated with the MTHFR C677T variant; however, no significant association was found with the MTHFR A1298C variant.

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.

Inherited prothrombotic risk factors in children with first ischemic stroke

Stroke in children is a heterogeneous disorder. Over 100 risk factors for stroke have been reported and genetic predisposition to stroke has been established. The most frequently reported risk factors are congenital heart malformations, hemolytic anemias, collagen vascular diseases, some rare inborn metabolic disorders, trauma, infection and thrombophilia. The aim of this article is to provide an overview of investigated inherited prothrombotic risk factors in children with first ischemic stroke. Various prothrombotic risk factors have been investigated in pediatric stroke including elevated homocysteine and lipoprotein (a), antithrombin, protein C and protein S deficiency, Factor V Leiden, Factor II G20210A and plasminogen activator inhibitor-1 4G/5G polymorphism. Despite similar criteria for inclusion of different studies in meta-analyses investigating first ischemic stroke in children, the obtained results were not consistent for all prothrombotic risk factors. The discrepancies found could be explained by methodological issues like different sample sizes, patient populations included and lack of controls. In order to provide the necessary power for randomized control trials, multi-center, multi-national approaches like International Pediatric Stroke Study have been initiated with the aim to describe risk factors for childhood stroke and explore their relationship with presentation, age, geography, and infarct characteristics. Although it is evident from numerous studies that the frequency of inherited prothrombotic factors is increased in pediatric stroke, single thrombophilia does not fully explain stroke in a child as it represents only a mild risk factor. Further studies are needed, as improved understanding of underlying mechanisms will improve primary and secondary prevention of childhood stroke.

Inherited thrombophilia in pediatric ischemic stroke: an Egyptian study

Pediatric stroke is relatively uncommon, with often subtle clinical presentations. Numerous predisposing risk factors can be both inherited and acquired, including cardiac disease, vascular abnormalities, infectious diseases, collagen tissue diseases, inborn errors of metabolism, anticardiolipin antibody, lupus anticoagulant, deficiencies of protein C, protein S, antithrombin, or plasminogen, and prothrombotic mutations. We explored risk factors, clinical features, and neuroimaging among Egyptian children with ischemic stroke, and estimated the prevalence of inherited thrombophilia. We included 20 children with ischemic stroke, recruited from the Pediatric Neurology Outpatient Clinic (Ain Shams University). Basic clinical evaluations for stroke and genotyping for factor V 1691 G-A (factor V Leiden), prothrombin 20210 G-A mutations, and methylenetetrahydrofolate reductase 677 C-T polymorphisms were performed using real-time polymerase chain reaction, with fluorescent melting curve detection analysis. Ten patients (50%) manifested methylenetetrahydrofolate reductase polymorphisms (six homozygotes and four heterozygotes). Heterozygous factor V Leiden was present in five (25%), whereas prothrombin mutation was present in only one (5%). Five patients (25%) manifested combined prothrombotic abnormalities. Thirteen demonstrated evidence of inherited thrombophilic disorder; 25% manifested more than one mutation. For appropriate risk assessment, even in the presence of overt acquired thrombotic risk factors, physicians should request complete thrombophilia screening for patients with 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.

Retrospective approach to methylenetetrahydrofolate reductase mutations in children

Methylenetetrahydrofolate reductase reduces methyltetrahydrofolate, a cosubstrate in the remethylation of homocysteine, from methylenetetrahydrofolate. Congenital defects, hematologic tumors, and intrauterine growth retardation can occur during childhood. This study evaluated clinical and laboratory treatment approaches in children diagnosed with methylenetetrahydrofolate reductase mutations. Our group included 23 boys and 14 girls, aged 103.4 ± 70.8 months S.D. Clinical findings of patients and homocysteine, vitamin B12, folate, hemogram, electroencephalography, cranial magnetic resonance imaging, and echocardiography data were evaluated in terms of treatment approach. Our patients' findings included vitamin B12 at 400.4 ± 224.6 pg/mL S.D. (normal range, 300-700 pg/mL), folate at 10.1 ± 4.5 ng/mL S.D. (normal range, 1.8-9 ng/mL), and homocysteine at 8.4 ± 4.7 μmol/L S.D. (normal range, 5.5-17 μmol/L). Eighty-eight percent of patients demonstrated clinical findings. In comparisons involving categorical variables between groups, χ(2) tests were used. No relationship was evident between mutation type, laboratory data, and clinical severity. All mothers who had MTHFR mutations and had babies with sacral dimples had taken folate supplements during pregnancy. To avoid the risk of neural tube defects, pregnant women with a MTHFR mutation may require higher than normally recommended doses of folic acid supplementation for optimum health.

The effect of folinic acid supplementation on homocysteine concentrations in newborns

OBJECTIVE

The incidence of cerebrovascular accidents (CVA) occurring perinatally is relatively high and aspects of the multifactorial pathophysiology remain unclear. Elevated homocysteine concentrations have been shown to be associated with an increased risk for CVA in children and even in newborns. We studied the possible homocysteine lowering effect of folinic acid in newborns.

METHOD

We included 37 newborns in our prospective randomized folinic acid (given as 5-formyltetrahydrofolate) intervention study from patients admitted to our neonatal intensive care unit (18 controls, 19 intervention group). We measured total homocysteine (tHcy) and plasma folate concentrations at three time points (baseline, 1 and 2 weeks after intervention). The intervention group was treated with folinic acid (70 μg/kg/day) for 2 weeks. We calculated median concentrations (25th and 75th percentiles).

RESULTS

Median tHcy concentrations at the three time points did not differ from each other in the control group nor in the intervention group. We also could not observe different tHcy concentrations between both groups. Plasma folate concentrations increased in the intervention group (mean increase 167% (95% confidence interval (CI) -291, 625)) compared with control group (mean increase -12% (95% CI -132, 108)), P for treatment effect: 0.03.

CONCLUSION

We could not demonstrate a homocysteine lowering effect of folinic acid administration in newborns. This indicates that one carbon metabolism in newborns differs form adults. Cobalamin might be a better strategy to lower tHcy concentrations in newborns.

Hyperhomocysteinemia Prevalence Among Patients With Venous Thromboembolism

The aim of this study is to evaluate the plasma total homocysteine level in patients with venous thromboembolism (VTE) and to investigate the effect of different risk factors on plasma levels. Ninety-three-patients with VTE and 37-control participants diagnosed with other than VTE were included in the study. Plasma homocysteine levels and the factors affecting plasma homocysteine levels were evaluated. Plasma homocysteine level was higher among patients with VTE compared to the controls independent from vitamin B12 and folate levels. The prevalence of hyperhomocysteinemia in VTE was 63%. Plasma homocysteine level was higher in patients with PE than deep venous thrombosis (DVT; 23 ± 13.7 vs 16 ± 5.8 μmol/L, P = .018). With regression analysis hyperhomocysteinemia was found to be associated with a 4.8-fold increased risk of VTE. Hyperhomocysteinemia is a common and possibly modifiable risk factor that should be considered when screening patients with VTE. Secondary causes of hyperhomocysteinemia especially vitamin B12 deficiency should be monitored in patients with VTE to prevent recurrences.

The T allele of the 677C>T polymorphism of methylenetetrahydrofolate reductase gene is associated with an increased risk of ischemic stroke in Polish children

Ischemic stroke is a very rare and multifactorial disease in children. The aim of the study was to analyze the relationship between the methylenetetrahydrofolate reductase (MTHFR) 677C>T polymorphism and stroke in Polish children and to observe whether there is any significant transmission of MTHFR alleles from heterozygous parents to their affected offspring. We analyzed 64 patients with stroke, 122 parents, and 59 healthy children. The MTHFR polymorphism was genotyped using polymerase chain reaction (PCR)-restriction fragment length polymorphism. The T allele was more frequent in the stroke group (38%) than in controls (25%, P = .029, odds ratio = 1.84). We also found higher frequency of T allele in male patients compared to male controls (46% vs. 25%, P = .009, odds ratio = 2.53). The number of T allele carriers was again more prevalent in boys with stroke (71%) than in healthy boys (45%, P = .023, odds ratio = 3.09). The T allele was significantly transmitted in male patients (P < .019). We conclude that the MTHFR 677C>T polymorphism may be considered as a genetic risk factor of childhood stroke, especially in boys.

Methylenetetrahydrofolate reductase gene polymorphism and childhood stroke

Genotyping for the methylenetetrahydrofolate reductase gene (MTHFR) has been recommended for part of the evaluation for underlying prothrombotic state in childhood stroke; however, studies are inconclusive regarding the role of this gene and also the role of hyperhomocysteinemia, which is the putative mechanism by which MTHFR polymorphism is related to stroke. The prevalence of MTHFR polymorphism in childhood arterial ischemic stroke and cerebral sinovenous thrombosis was compared with that of a reference population, and prevalence of hyperhomocysteinemia was reviewed. In arterial ischemic stroke, the prevalence of at-risk methylenetetrahydrofolate reductase genotypes was 27%, and in cerebral sinovenous thrombosis it was 13%; the population prevalence was 26%. The odds ratio for at-risk genotype in childhood arterial ischemic stroke was 1.06 (95% confidence interval, 0.22-4.0); in cerebral sinovenous thrombosis, it was 0.42 (95% confidence interval, 0.01-3.6). No tested cases had hyperhomocysteinemia. MTHFR polymorphism and hyperhomocysteinemia were not risk factors in childhood arterial ischemic stroke or cerebral sinovenous thrombosis in the Intermountain West region.

Prothrombotic polymorphisms, mutations, and their association with pediatric non-cardioembolic stroke in Asian-Indian patients

Genes involved in the hemostatic mechanism are logical candidate genes for association studies in prothrombotic conditions such as stroke. Since the underlying etiology in pediatric strokes is different than adults, looking for genetic causes would be the logical thing to do in the pediatric stroke population. Fifty-eight Asian-Indian stroke patients below 15 years of age and equal number of age- and sex-matched healthy controls were the subjects for the study. The subjects were screened for 13 polymorphisms and three mutations spread across seven different candidate genes involved in the hemostatic system. Of the 13 polymorphisms and three mutations studied, four polymorphisms, HPA-I, TAFI 147Ala>Thr, methylene tetrahydrofolate reductase (MTHFR) 677 C>T, and MTHFR 1298 A>C, showed significant association with the disease phenotype. MTHFR 677 C>T showed the strongest association and therefore may have a strong predisposing role for pediatric strokes. Gene-gene interaction studies showed a strong interaction between HPA-I and MTHFR 677 C>T polymorphism. The wild type of both these polymorphisms synergistically showed a strong protective effect [p < 0.0001, O.R: 10.06(4.26-23.71)]. Polymorphisms in HPA-I and MTHFR may have important predisposing roles in the development of pediatric stroke.

Prevalence and effects of gene-gene and gene-nutrient interactions on serum folate and serum total homocysteine concentrations in the United States: findings from the third National Health and Nutrition Examination Survey DNA Bank

BACKGROUND

Abnormalities of folate and homocysteine metabolism are associated with a number of pediatric and adult disorders. Folate intake and genetic polymorphisms encoding folate-metabolizing enzymes influence blood folate and homocysteine concentrations, but the effects and interactions of these factors have not been studied on a population-wide basis.

OBJECTIVE

The objective was to assess the prevalence of these genetic polymorphisms and their relation to serum folate and homocysteine concentrations.

DESIGN

DNA samples from 6793 participants in the third National Health and Nutrition Examination Survey (NHANES III) during 1991-1994 were genotyped for polymorphisms of genes coding for folate pathway enzymes 5,10-methylenetetrahydrofolate reductase (MTHFR) 677C-->T and 1298A-->C, methionine synthase reductase (MTRR) 66A-->G, and cystathionine-beta-synthase 844ins68. The influence of these genetic variants on serum folate and homocysteine concentrations was analyzed by age, sex, and folate intake in 3 race-ethnicity groups.

RESULTS

For all race-ethnicity groups, serum folate and homocysteine concentrations were significantly related to the MTHFR 677C-->T genotype but not to the other polymorphisms. Persons with the MTHFR 677 TT genotype had a 22.1% (95% CI: 14.6%, 28.9%) lower serum folate and a 25.7% (95% CI: 18.6%, 33.2%) higher homocysteine concentration than did persons with the CC genotype. Moderate daily folic acid intake (mean: 150 microg/d; 95% CI: 138, 162) significantly reduced the difference in mean homocysteine concentrations between those with the MTHFR 677 CC and TT genotypes. We found a significant interaction between MTHFR 677C-->T and MTRR 66A-->G on serum homocysteine concentrations among non-Hispanic whites.

CONCLUSIONS

The MTHFR 677C-->T polymorphism was associated with significant differences in serum folate and homocysteine concentrations in the US population before folic acid fortification. The effect of MTHFR 677C-->T on homocysteine concentrations was reduced by moderate daily folic acid intake.

Total homocysteine, B-vitamins and genetic polymorphisms in patients with classical phenylketonuria

Hyperhomocysteinemia has occasionally been reported in patients with phenylketonuria (PKU) and B-vitamin deficiency. In our study total homocysteine (tHcy) and B-vitamins were measured in treated PKU patients and healthy controls. In the patients, dietary parameters and genetic polymorphisms affecting the Hcy pathway were investigated to identify parameters modulating tHcy. A case control study including 37 PKU patients and 63 healthy controls was conducted. t-Tests for independent samples were used to test between groups. Multiple regressions with tHcy as dependent variable were calculated. Hardy-Weinberg expectations were tested against the observed distribution of genotypes applying the Chi-square goodness-of-fit method. THcy concentrations were not significantly different (p=0.059) while folate and cobalamin (Cbl) concentrations were significantly higher in PKU patients compared to controls. However, 29.7% of patients had tHcy concentrations >97th centile. THcy did not vary with age nor correlate with folate and Cbl concentrations probably due to high saturatory levels. The presence of genetic polymorphisms had no impact on tHcy. In conclusion, in PKU patients treated with amino acid mixtures enriched with B-vitamins, tHcy is not significantly higher than in healthy controls, but tHcy concentrations exceed the 97th centile in about one third of patients. Even higher B-vitamin saturation may be required to further decrease tHcy concentrations and factors generally influencing tHcy such as betaine are to be investigated in PKU patients in the future.

Association of methylenetetrahydrofolate reductase (MTHFR-677 and MTHFR-1298) genetic polymorphisms with occlusive artery disease and deep venous thrombosis in Macedonians

AIM

To analyze the association of methylenetetrahydrofolate reductase polymorphisms (MTHFR-677 and MTHFR-1298) with occlusive artery disease and deep venous thrombosis in Macedonians.

METHODS

We examined 83 healthy respondents, 76 patients with occlusive artery disease, and 67 patients with deep venous thrombosis. Blood samples were collected and DNA was isolated from peripheral blood leukocytes. Identification of MTHFR mutations was done with CVD StripAssay (ViennaLab, Labordiagnostika GmbH, Vienna, Austria) and the population genetics analysis package, PyPop, was used for the analysis. Pearson P values, crude odds ratio, and Wald's 95% confidence intervals were calculated.

RESULTS

The frequency of C alleles of MTHFR-677 was 0.575 in patients with deep venous thrombosis, 0.612 in patients with occlusive artery disease, and 0.645 in healthy participants. The frequency of T allele of MTHFR-677 was lower in healthy participants (0.355) than in patients with occlusive artery disease (0.388) and deep venous thrombosis (0.425). The frequency of A allele for MTHFR-1298 was 0.729 in healthy participants, 0.770 in patients with occlusive artery disease, and 0.746 in patients with deep venous thrombosis. The frequency of C allele of MTHFR-1298 was 0.271 in healthy participants, 0.230 in patients with occlusive artery disease, and 0.425 in patients with deep venous thrombosis. No association of MTHFR-677 and MTHFR-1289 polymorphisms with occlusive artery disease and deep venous thrombosis was found, except for the protective effect of MTHFR/CA:CC diplotype for occlusive artery disease.

CONCLUSION

We could not confirm a significant association of MTHFR-677 and MTHFR-1289 polymorphisms with occlusive artery disease or deep venous thrombosis in Macedonians, except for the protective effect of MTHFR/CA:CC diplotype against occlusive artery disease.

The importance of thrombotic risk factors in the development of idiopathic sudden hearing loss

Impaired cochlear blood circulation has been suggested to cause sudden hearing loss. In this study, the role of factor V 1691 G-A (FV 1691 G-A), prothrombin 20210 G-A (PT 20210 G-A), methylene tetrahydrofolate reductase 677 C-T (MTHFR 677 C-T), factor V 4070 A-G (FV 4070 A-G), endothelial cell protein C receptor (EPCR) gene 23-bp insertion, and plasminogen activator inhibitor-1 (PAI-1) 4G/5G mutation was assessed. Fifty-three patients with idiopathic sudden sensorineural hearing loss and 80 individuals comprising the control group were included in this study. The frequency for FV 1691 A was 6.2% in the patient group and 3.7% in the control group, PT 20210 G-A was 1.2% in the patient group and 1.9% in the control group, and FV 4070 A-G was 7.5% in the patient group and 11.3% in the control group. The frequency of MTHFR 677 C-T was significantly higher in the patient group than in the control group, with a P value of .03. PAI-1-675 4G/5G polymorphism was found to be 71.2% and 69.8%, in the control group and the patient group, respectively. The EPCR 23-bp insertion was 0% in the control group and was found in 3 patients (3.7%), which needs further study.

The 677 C/T MTHFR polymorphism is associated with essential hypertension, coronary artery disease, and higher homocysteine levels

BACKGROUND

Essential hypertension (EH) and cardiovascular disease are common, multifactorial disorders likely to be influenced by multiple genes of modest effect. The C677T methylenetetrahydrofolate reductase (MTHFR) gene polymorphism is related to MTHFR enzyme activity and to plasma homocysteine (Hcy) concentration. This study was designed to investigate an association of this polymorphism with coronary artery disease (CAD), EH, and healthy subjects.

METHODS

In this study, we measured serum folate, serum vitamin B12, and plasma homocysteine and determined the MTHFR C677T genotype of 78 patients with essential hypertension, 100 patients with coronary artery disease, and 100 healthy subjects. MTHFR genotypes were assessed by real-time polymerase chain reaction.

RESULTS

CC, CT, and TT genotype frequencies were 52, 44.0, and 4.0% in patients with CAD, respectively. In patients with essential hypertension, the CC, CT, and TT genotype frequencies were 46.2, 41.0, and 12.8%, respectively. In control subjects, the CC, CT, and TT genotype frequencies were 72.0, 26.0, and 2.0%, respectively. The C allele was significantly more frequent in controls compared with patients with EH (p<0.05), and CC genotypes were more frequent in controls compared to patients with EH and CAD. Homocysteine level was higher in TT genotypes in CAD patients compared with CC and CT genotypes (p<0.01). MTHFR gene polymorphism is an independent risk factor for EH but not for CAD.

CONCLUSIONS

The TT genotype of the 677C/T MTHFR polymorphism is associated with EH and CAD. In addition, TT genotypes had higher plasma Hcy levels in CAD patients compared with CC and CT genotypes. MTHFR gene polymorphism is an independent risk factor for EH but not for CAD.

Prothrombotic risk factors in the evaluation and management of perinatal stroke

The ischemia in children affected by perinatal stroke has long been thought to be driven by nonhematologic maternal and perinatal events. New information from clinical studies, however, tells us that plasma-phase risk factors, such as factor V Leiden, elevated lipoprotein (a), and mutations in MTHFR, may be important in the pathogenesis of perinatal stroke, if not always in the risk of recurrence. With regard to stroke recurrence, this risk is only about 2% according to the largest follow-up study to date, and certainly less than 5%. Nonetheless, when strokes do recur, they tend to be associated with the presence of plasma-phase risk factors in the affected child, suggesting that a small percentage of children with a first perinatal stroke may benefit from anticoagulation therapy, both to prevent stroke recurrence as well as occurence of a second, non-CNS thrombotic event. Counselling of parents with regard to subsequent pregnancies should always include medical management of systemic maternal disorders, such as diabetes, persistently elevated antiphospholipid antibodies, and inherited maternal hypercoagulability states.

Hypercoagulation Testing in Ischemic Stroke

Context.—The utility of laboratory testing for hypercoagulability in the setting of stroke is uncertain.

Objective.—To review the current literature and to make recommendations with regard to laboratory testing for various hypercoagulability risk factors for ischemic stroke.

Data Sources.—Published articles studying the utility of various hypercoagulation tests in predicting initial and/or recurrent stroke or transient ischemic attack as well as cerebral vein thrombosis were collected and reviewed, with an emphasis on prospective studies.

Conclusions.—Certain tests, such as C-reactive protein, homocysteine, antiphospholipid antibodies, and lipoprotein(a), may be useful in patients with a history of stroke or at high risk for stroke, as evidenced by prospective data. Factor V Leiden, prothrombin G20210A, protein C, protein S, and antithrombin are not recommended for routine testing but may be useful in certain populations, such as in pediatric patients or in patients with cerebral vein thrombosis.

Methylenetetrahydrofolate reductase gene polymorphisms are associated with ischemic and hemorrhagic stroke: Dual effect of MTHFR polymorphisms C677T and A1298C

Hyperhomocysteinemia is an independent risk factor for ischemic stroke. The enzyme methylenetetrahydrofolate reductase (MTHFR) plays a critical role in modulating the levels of plasma homocysteine. Two polymorphisms in the MTHFR gene, C677T, A1298C result in reduced enzyme activity. The mechanisms of ischemic and hemorrhagic stroke are not well understood. Although controversial, previous studies have shown evidence of causality of both stroke subtypes in patients with methylenetetrahydrofolate reductase gene polymorphisms. Therefore, we examined whether the C677T and A1298C polymorphisms of MTHFR gene are genetic risk factors for both ischemic and hemorrhagic stroke in a Turkish Caucasian population. In a case-control study, 120 total unrelated stroke patients (92 ischemic stroke, 28 hemorrhagic stroke), and 259 healthy controls were genotyped for C677T and A1298C polymorphisms of the MTHFR gene using a PCR-RFLP based-method. The MTHFR 1298C allele (chi(2)=8.589; P=0.014), C1298C genotype (OR=2.544; P=0.004), and C677C/C1298C compound genotype (OR=3.020; P=0.001) were associated with overall stroke. The MTHFR 1298C allele (chi(2)=11.166; P=0.004), C1298C genotype (OR=2.950; P=0.001), and C677C/C1298C compound genotype (OR=3.463, P=0.0001) were strongly associated with ischemic stroke. Interestingly however, the MTHFR 677T allele (chi(2)=6.033; P=0.049), T677T genotype (OR=3.120; P=0.014), and T677T/A1298A compound genotype (OR=4.211; P=0.002) were associated with hemorrhagic stroke. In conclusion, the C677T and A1298C polymorphisms of the MTHFR gene are genetic risk factors for hamorrhagic and ischemic stroke respectively, independent of other atherothrombotic risk factors.

Confirmation of the R653Q polymorphism of the trifunctional C1-synthase enzyme as a maternal risk for neural tube defects in the Irish population

The risk of neural tube defects (NTDs) is known to have a significant genetic component that could act through either the NTD patient and/or maternal genotype. The success of folic acid supplementation in NTD prevention has focused attention on polymorphisms within folate-related genes. We previously identified the 1958G>A (R653Q) polymorphism of the trifunctional enzyme MTHFD1 (methylenetetrahydrofolate-dehydrogenase, methenyltetrahydrofolate-cyclohydrolase, formyltetrahydrofolate synthetase; often referred to as 'C1 synthase') as a maternal risk for NTDs, but this association remains to be verified in a separate study to rule out a chance finding. To exclude this possibility, we genotyped an independent sample of mothers with a history of an NTD-affected pregnancy derived from the same Irish population. In this sample there was a significant excess of 1958AA homozygote mothers of NTD cases (n=245) compared to controls (n=770). The direction and magnitude of risk (odds ratio 1.49 (1.07-2.09), P=0.019) is consistent with our earlier finding. Sequencing of the MTHFD1 gene revealed that this association is not being driven by another common variant within the coding region. We have established that the MTHFD1 1958G>A polymorphism has a significant role in influencing a mother's risk of having an NTD-affected pregnancy in the Irish population.

Prevalence of methylenetetrahydrofolate reductase 677T and 1298C alleles and folate status: a comparative study in Mexican, West African, and European populations

BACKGROUND

Methylenetetrahydrofolate reductase (MTHFR) 677C-->T polymorphism is heterogeneously distributed worldwide, with the highest and lowest frequencies of the T allele in Mexico and Africa, respectively, and a south-to-north gradient in Europe. Distribution of MTHFR 1298A-->C is less well known. It has been hypothesized that 677T frequency could result in part from gene-nutrient interactions.

OBJECTIVE

The objective was to compare the association of 677T and 1298C alleles with plasma concentrations of homocysteine, folate, and vitamin B-12 in geographical areas with contrasting 677T allele frequencies.

DESIGN

Healthy young adults (n = 1277) were recruited in Mexico City, the West African countries of Bénin and Togo, France, and Sicily (Italy). Homocysteine, folate, and vitamin B-12 were measured in plasma, and MTHFR polymorphisms were measured in genomic DNA.

RESULTS

Mexico City and Sicily reported the highest and Bénin and Togo reported the lowest plasma concentrations of folate. Mexico City had the highest 677T allele prevalence and the lowest influence of 677TT genotype on homocysteine, whereas the opposite was observed in Africa. The prevalence of the 1298C allele was lowest in the Mexicans and Africans and highest in the French. The percentage of the 677T genotype was significantly associated with the folate concentrations in 677CC carriers in a univariate analysis (R = 0.976; 95% CI: 0.797, 0.996; P < 0.0002) and in a multiple regression model that included homocysteine, vitamin B-12, and age (P = 0.0002).

CONCLUSION

Our data agree with the hypothesis of a gene-nutrient interaction between MTHFR 677C-->T polymorphism and folate status that may confer a selective advantage of TT-homozygous genotype when dietary intake of folate is adequate, at least in the areas studied.

Sequence variations within the genes related to hemostatic imbalance and their impact on coronary artery disease in Turkish population

Coronary artery disease (CAD) is reported to be associated with some genetic risk factors. Since identification of genetic risk factors for CAD in different ethnic groups is important for the development of new intervention and prevention programs, we investigated the association between the R353Q and -323ins10 polymorphisms in Factor VII gene, C677T mutation in MTHFR, Factor V Leiden and PT G20210A mutations and CAD in Turkish population. The promoter region of the PAI-1 gene was also screened by SSCA (single-stranded conformation analysis) using specifically designed primers. 137 CAD patients with early onset documented by coronary angiography and 41 individuals who had no significant coronary stenosis by angiography as control group were screened for the identification of the polymorphisms. In conclusion, Factor V Leiden was found to be an independent genetic risk factor for CAD in Turkish population. Combined risk assessment indicated that the coexistence of two other inherited thrombophilia markers, namely MTHFR C677T and PT G20210A with Factor V Leiden may increase the risk of the development of the disease in this population. The results of the present study show that there is no statistically significant association between the two polymorphisms in Factor VII gene, MTHFR C677T polymorphism, PT G20210A polymorphism, 4G/5G polymorphism of PAI-1 and CAD in Turkish population.

A polymorphism in the MTHFD1 gene increases a mother's risk of having an unexplained second trimester pregnancy loss

Low maternal folate or vitamin B12 status has been implicated in numerous pregnancy complications including spontaneous abortion. The primary aim of this study was to test a polymorphism within the trifunctional folate enzyme MTHFD1 (5,10-methylenetetrahydrofolate dehydrogenase, 5,10-methenyltetrahydrofolate cyclohydrolase, 10-formyltetrahydrofolate synthetase) for an association with a mother's risk of having an unexplained second trimester pregnancy loss. We genotyped 125 women who had at least one unexplained spontaneous abortion or intrauterine fetal death between 13 and 26 weeks gestation and 625 control women with no history of prior pregnancy loss. Our study is the first to identify an association between the MTHFD1 1958G-->A (R653Q) polymorphism and the maternal risk of having an unexplained second trimester pregnancy loss. Women who are MTHFD1 1958AA homozygous have a 1.64-fold increased risk of having an unexplained second trimester loss compared to women who are MTHFD1 1958AG or 1958GG [OR 1.64 (1.05-2.57), P = 0.03]. It has been reported that polymorphisms in 5,10-methylenetetrahydrofolate reductase (MTHFR), 677C-->T (A222V), transcobalamin II (TCII), 776C-->G (P259R), are associated with pregnancy loss. Both variants were tested in this study. Neither showed evidence of significantly affecting the maternal risk of having a second trimester pregnancy loss. In conclusion, the MTHFD1 1958AA genotype may be an important maternal risk factor to consider during pregnancy.

Prothrombotic factors in children with stroke or porencephaly

OBJECTIVE

This study compared the frequencies of genetic and functional coagulation abnormalities in children with arterial ischemic stroke or porencephaly with frequencies in previously published studies.

METHODS

A series of 59 children (age 0-18 years) with arterial ischemic stroke or porencephaly were referred to the National Institutes of Health. A blood sample, buccal smear sample, questionnaire, and pedigree were requested for each child. Blood samples were analyzed for protein C (PC); protein S; antithrombin (AT); activated PC resistance (APCR); lipoprotein (a) [Lp(a)]; lupus anticoagulant; anticardiolipin antibodies; and the methylenetetrahydrofolate reductase C677T (MTHFR), factor V G1619A, factor II G20210A (PT), plasminogen activator inhibitor-1 4G6755G, and tissue factor pathway inhibitor C536T mutations. The frequency of each coagulation abnormality was compared with published international pediatric stroke case and control rates.

RESULTS

At least 1 prothrombotic abnormality was identified in 63% (36 of 57) of children studied, including plasminogen activator inhibitor-1 4G6755G (15 of 56), MTHFR (12 of 56), elevated Lp(a) (12 of 59), APCR (11 of 58), factor V G1619A (5 of 57), PT (3 of 57), PC deficiency (1 of 59), and AT deficiency (1 of 59). The MTHFR mutation, elevated Lp(a), the PT mutation, and AT deficiency rates were similar to rates in cases and more common than control subjects in previously published studies. The rate of children with APCR or multiple abnormalities was higher than in previous pediatric stroke studies. A family history of early thrombosis was identified in one third of the children with a prothrombotic abnormality.

CONCLUSIONS

Two thirds of children in this study had at least 1 of the prothrombotic risk factors tested, and several children had multiple risk factors. These results provide additional evidence that prothrombotic abnormalities are common among children with AIS or porencephaly.

Analysis of methionine synthase reductase polymorphisms for neural tube defects risk association

Methionine synthase reductase (MTRR) regenerates methylated cobalamin levels from the oxidised cob(II)alamin form and in so doing plays a crucial role in maintaining the active state of methionine synthase (MTR). MTR is an essential enzyme catalyzing the conversion of homocysteine to methionine. Single nucleotide polymorphisms (SNPs) within the MTRR gene may potentially compromise MTR activity leading to elevated homocysteine levels, a known risk factor for neural tube defects (NTDs). We studied the MTRR polymorphisms I22M (66A-->G), S175L (524C-->T), and K350R (1049A-->G) as potential NTD risk factors in a large homogeneous Irish NTD population. Degree of risk was assessed via case/control comparison, log-linear analysis, and transmission disequilibrium testing. No association was found between NTDs and I22M in mothers (p = 0.16, OR1.14 [0.95-1.38], n = 447) or cases (p = 0.13, OR1.15 [0.96-1.38], n = 470) compared to controls (n = 476). A dominant I22M paternal effect was found through case/control comparison and log-linear modelling (p = 0.019) (goodness-of-fit p=0.91, OR 1.46 [1.10-1.93], n = 423). No significant NTD association was found with S175L or K350R in cases or their parents and no interactions were observed between these polymorphisms and the D919G variant of MTR or the A222V variant of 5,10-methylenetetrahydrofolate reductase (MTHFR). We also compared the frequencies of I22M, S175L, and K350R in African-Americans versus American-Caucasians. The frequencies of I22M and K350R differed significantly between the two groups (p = 0.0005 and p = 0.0001, respectively). Our findings do not support an important role for these MTRR variants in NTDs.

Thrombophilia and first arterial ischaemic stroke: a systematic review

AIMS

To undertake a systematic review of the literature reporting the prevalence of thrombophilia in children with a first arterial ischaemic stroke (AIS).

METHODS

Systematic review of case-control studies reporting data for prevalence of protein C, S, and antithrombin (AT) deficiencies, activated protein C resistance (APCr), total plasma homocysteine >95th centile, the thrombophilic mutations factor V1691 GA, prothrombin 20210GA, and MTHFR C677T in children with first, radiologically confirmed, AIS.

RESULTS

Of 1437 potentially relevant citations, 18 met inclusion criteria. A total of 3235 patients and 9019 controls had been studied. Results of meta-analyses were expressed as pooled odds ratios (OR) relating the prevalence of the thrombophilic condition in children with AIS to that in controls. The pooled OR (and 95% CI) were: protein C deficiency, 6.49 (2.96 to 14.27); protein S deficiency, 1.14 (0.34 to 3.80); AT deficiency, 1.02 (0.28 to 3.67); APCr, 1.34 (0.16 to 11.52); FV1691 GA, 1.22 (0.80 to 1.87); PT20210GA, 1.10 (0.51 to 2.34); MTHFR C677T, 1.70 (1.23 to 2.34); and total plasma homocysteine >95th centile, 1.36 (0.53 to 3.51). There was no statistical heterogeneity within these data.

CONCLUSIONS

All factors examined were more common in children with first AIS than in controls, and significantly so for protein C deficiency and the MTHFR C677T mutation. The implications of thrombophilia for prognosis and recurrence need to be established before clinical recommendations can be made regarding investigation and treatment of children with AIS.