Unraveling Mechanisms of Cryptogenic Stroke at the Genetic Level: A Systematic Literature Review

Background A substantial proportion of ischemic strokes remain cryptogenic, which has important implications for secondary prevention. Identifying genetic variants related to mechanisms of stroke causes may provide a chance to clarify the actual causes of cryptogenic strokes. Methods and Results In a 2-step process, 2 investigators independently and systematically screened studies that reported genetic variants in regard to stroke causes that were published between January 1991 and April 2021. Studies on monogenetic disorders, investigation of vascular risk factors as the primary end point, reviews, meta-analyses, and studies not written in English were excluded. We extracted information on study types, ancestries, corresponding single nucleotide polymorphisms, and sample and effect sizes. There were 937 studies screened, and 233 were eligible. We identified 35 single nucleotide polymorphisms and allele variants that were associated with an overlap between cryptogenic strokes and another defined cause. Conclusions Associations of single variants with an overlap between cryptogenic stroke and another defined cause were limited to a few polymorphisms. A limitation of all studies is a low granularity of clinical data, which is of major importance in a complex disease such as stroke. Deep phenotyping is in supposed contradiction with large sample sizes but needed for genome-wide analyses. Future studies should attempt to address this restriction to advance the promising approach of elucidating the cause of stroke at the genetic level. Especially in a highly heterogenous disease such as ischemic stroke, genetics are promising to establish a personalized approach in diagnostics and treatment in the sense of precision medicine.

Inhibition of the BCL6/miR-31/PKD1 axis attenuates oxidative stress-induced neuronal damage

Ischemic stroke (IS) is one of the most common cerebrovascular diseases worldwide. The aberrant expression of BCL6 has been previously implicated in the pathogenesis of IS. Meanwhile, miR-31 is known as a target of BCL6, and has also been suggested to diminish cell damage by suppressing the PKD1 expression. Expanding on this relationship, the current study set out to investigate whether BCL6 participates in ischemic stroke by targeting PKD1. Firstly, IS models were established in vitro and in vivo. TUNEL staining and MTT assay were performed to examine the apoptosis and cell survival. In addition, qRT-PCR and Western blot analysis were applied to examine the expression patterns of the BCL6/miR-31/PKD1 axis and its downstream pathway. Bioinformatics analysis was used to predict the target of miR-31. It was found that BCL6 over-expression promoted ODG-induced increase of apoptosis and decreased the cell survival and miR-31 expression levels, whereas the opposite effects were noted in vitro and in vivo models of IS that were treated with shBCL6. Furthermore, miR-31 down-regulation blocked the effect of BCL6 on ODG-induced cell injury. It was also verified that miR-31 directly-targets PKD1. Also, OGD induced the PKD1 expression and activation of the JAK2/STAT3 pathway, while down-regulation of PKD1 inhibited the OGD-induced cell injury and JAK2/STAT3 pathway activation. Lastly, down-regulation of BCL6 in brain brought about a significant reduction in the size of cerebral infarction and oxidative stress levels in IS mice. Collectively, our findings suggest that inhibition of BCL6 may attenuate oxidative stress-induced neuronal damage by targeting the miR-31/PKD1 axis.

Genome-wide blood DNA methylation analysis in patients with delayed cerebral ischemia after subarachnoid hemorrhage

Little is known about the epigenetic changes associated with delayed cerebral ischemia (DCI) pathogenesis after subarachnoid hemorrhage (SAH). Here, we investigated genome-wide DNA methylation profiles specifically associated with DCI, which is a major contributor to poor clinical outcomes. An epigenome-wide association study (EWAS) and quantitative real-time PCR (qRT-PCR) were conducted in 40 SAH patients (DCI, n = 13; non-DCI, n = 27). A replication study using bisulfite modification and methylation-specific PCR was further performed in 36 patients (DCI, n = 12; non-DCI, n = 24). The relative degree of methylation was described as the median and 25th–75th percentile. No significant differences in clinical characteristics between DCI and non-DCI groups were observed. Among the top 10 differentially methylated genes analyzed via EWAS, two aberrantly methylated CpG sites of cg00441765 (INSR gene) and cg11464053 (CDHR5 gene) were associated with decreased mRNA expression (2^−ΔCt). They include INSR [0.00020 (0.00012–0.00030) in DCI vs. 0.00050 (0.00030–0.00068) in non-DCI] and CDHR5 [0.114 (0.053–0.143) in DCI vs. 0.170 (0.110–0.212) in non-DCI]. Compared with non-DCI cases, patients with DCI exhibited an increased degree of methylation in the replication study: INSR, 0.855 (0.779–0.913) in DCI vs. 0.582 (0.565–0.689) in non-DCI; CDHR5, 0.786 (0.708–0.904) in DCI vs. 0.632 (0.610–0.679) in non-DCI. Hypermethylation of two novel genes, INSR and CDHR5 may serve as a biomarker for early detection of DCI following SAH.

Association between CYP2C19 gene polymorphisms and lipid metabolism in Chinese patients with ischemic stroke

Objective

The CYP2C19 genetic variation may be involved in the development of atherosclerotic cardiovascular disease (ASCVD). Serum lipid levels are important risk factors for ASCVD, but the effect of the CYP2C19 gene on serum lipid metabolism remains unclear. This retrospective cohort study investigated the relationship between the CYP2C19 gene polymorphism and serum lipid levels in patients with ischemic stroke (IS).

Methods

IS patients (n = 230) and control subjects (n = 100) were enrolled. All patients were diagnosed with IS via clinical manifestations and brain magnetic resonance imaging. All patients were genotyped.

Results

Triglyceride (TG), total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-c), and apolipoprotein B (ApoB) levels were significantly higher and high-density lipoprotein-cholesterol (HDL-c) and apolipoprotein A₁ (ApoA₁) levels were significantly lower in the IS group compared with the control group. Lower ApoA₁ levels and higher ApoB levels were significant predictive factors for IS. Patients with higher ApoB levels had a higher risk of IS recurrence. Compared with extensive metabolizers, intermediate and poor CYP2C19 metabolizers had a higher risk of IS recurrence.

Conclusions

Our study indicates CYP2C19 gene polymorphisms are related to lipid metabolism in patients with IS. IS patients who are poor CYP2C19 metabolizers may have a higher risk of disease recurrence.

miR-149 and miR-499 gene polymorphism and the incident of ischemic stroke in the Asian population: From a case-control study to meta-analysis

OBJECTIVES

MiRNAs are the most abundant class of regulatory non-coding RNA, which may exert a significant role in the pathogenesis of ischemic stroke(IS). Previous studies have focused on the relationship between miRNA polymorphism and IS risk, but the results remain inconsistent. Therefore, we first conducted a case-control study to explore the association, and subsequently performed a meta-analysis to further to clarify the association of miRNA polymorphism with risk of ischemic stroke.

PATIENTS AND METHODS

We first conducted a case-control study including 567 IS patients and 552 controls. Then we performed a meta-analysis combining the current study and previous studies with a total of 3015 cases and 2874 controls on miR-149 rs2292832 and 4119 cases and 4085 controls on miR-499 rs3746444 to further confirm our findings by searching PubMed, Web of Science and Chinese National Knowledge Infrastructure (CNKI) databases database up to Nov 2019.

RESULTS

In our case-control study, no association between miR-499 rs3746444, miR-149 rs2292832 and IS were found. When combined with previous studies, however, a significant relationship between miR-149 rs2292832 and ischemic stroke incident was found under recessive model and allelic model. In other words, CC genotype and C allele of miR-149 rs2292832 were increased risk of ischemic stroke.

CONCLUSION

Our meta-analysis results suggest that miR-149 rs2292832 might contribute to stroke susceptibility in the Asian populations.

The CD14 gene -159C/T polymorphism and the risk of ischemic stroke: a meta-analysis

BACKGROUND

To investigate the association between the CD14 -159C/T polymorphism and ischemic stroke (IS).

METHODS

Relevant literature was searched by retrieving EMBASE, Web of Science, Chinese National Knowledge Infrastructure, and PubMed databases. R version 3.33 software was applied to calculate pooled odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Seven qualified studies with a total of 2058 IS patients and 2123 controls were included. There was no significant association between the CD14 -159C/T polymorphism and IS risk in the total population (TT vs CC: OR = 0.84, 95% CI = 0.58-1.20; CT vs CC: OR = 0.96, 95% CI = 0.82-1.12; dominant model: OR = 1.02, 95% CI = 0.80-1.30; recessive model: OR = 0.82, 95% CI = 0.57-1.19). Similarly, subgroup analysis according to ethnicity and Hardy-Weinberg equilibrium also found no significant interrelation.

CONCLUSION

Our findings suggest that the CD14 -159C/T polymorphism does not contribute to the risk of IS. Well-designed studies with more subjects are required to further validate these results.

Association between MicroRNA-4669 Polymorphism and Ischemic Stroke in a Korean Population

Recent studies have explored the association between single-nucleotide polymorphisms (SNPs) in microRNAs (miRNAs) and ischemic stroke (IS). In particular, the associations of rs2910164 (miRNA-146A), rs11614913 (miRNA-196A2), and rs3746444 (miRNA-499A) were intensively studied in IS. In this study, we investigated the associations between SNPs in miRNAs and IS including rs2910164, rs11614913, and rs3746444 in a Korean population. For a pilot study, we selected 19 SNPs in pre-miRNA region (including mature miRNA region) and genotyped in 140 IS patients and 240 control subjects using the Fluidigm Dynamic Array. Our pilot study showed a weak association of rs79402775 in miRNA-933 (p = 0.044) and a relatively strong association of rs35196866 in miRNA-4669 (p = 0.016) with IS. From the pilot study, we selected rs79402775, rs35196866, and rs7202008 (miRNA-2117; p = 0.055) as candidate miRNA SNPs on IS and further genotyped these SNPs in 264 IS patients and 455 control subjects using direct sequencing. In addition, we further analyzed the associations of rs2910164, rs11614913, and rs3746444 that have been intensively studied in previous studies. In the further analysis, we found the significant association between rs35196866 and IS (p = 0.0014 in additive model and p = 0.00015 in dominant model; p = 0.00037 in allele frequency analysis). However, the association between rs2910164, rs11614913, rs3746444, rs79402775, and rs7202008 and IS was not shown. These results suggest that miRNA-4669 may be involved in the susceptibility of IS.

Correlation Between Altered DNA Methylation of Intergenic Regions of ITPR3 and Development of Delayed Cerebral Ischemia in Patients with Subarachnoid Hemorrhage

BACKGROUND

Delayed cerebral ischemia (DCI) is related to the major causes of morbidity and mortality in patients following subarachnoid hemorrhage (SAH); however, little is known about the role of epigenetics in the pathogenesis of DCI. We investigated the specific DNA methylation profile that may affect the expression of inositol 1-,4-,5-trisphosphate receptor (ITPR3) responsible for cerebral vasospasm following SAH.

METHODS

We prospectively studied patients with SAH between March 2015 and October 2018. The degree of methylation in the distal intergenic region (IGR) located on ITPR3 and gene expression were measured using methylation-specific polymerase chain reaction (MSP) and quantitative real-time polymerase chain reaction (qPCR). To investigate the regulatory mechanims of DNA hypermethylation, we further analyzed the mRNA expression of DNA methyltransferase (DNMT1) and ten-eleven translocation enzymes (TET1, TET2, and TET3).

RESULTS

A total of 42 patients were included in our analysis. Patients with SAH and DCI had significantly higher levels of methylation intensity of distal IGR upstream of ITPR3 than those without DCI (median, 0.941 [interquartile range (IQR), 0.857-0.984] versus (0.670 [IQR, 0.543-0.761]; P < 0.001). In addition, patients with DCI showed decreased mRNA expression of ITPR3 compared with patients without DCI (median, 0.039 [IQR, 0.030-0.045] vs. 0.047 [IQR, 0.038-0.064]; P = 0.0328). Patients with DCI had higher DNMT1 expression (P < 0.001) and lower TET1 expression (P = 0.040) than those without DCI; however, differences in TET2 and TET3 levels between the 2 groups were not statistically significant.

CONCLUSIONS

Hypermethylation of the distal IGR located upstream of ITPR3 is related to greater DCI development in patients with SAH. Further studies of the precise mechanisms of methylation degree and DCI development using in vitro and in vivo models are needed.

Diffusion kurtosis imaging of microstructural changes in brain tissue affected by acute ischemic stroke in different locations

The location of an acute ischemic stroke is associated with its prognosis. The widely used Gaussian model-based parameter, apparent diffusion coefficient (ADC), cannot reveal microstructural changes in different locations or the degree of infarction. This prospective observational study was reviewed and approved by the Institutional Review Board of Xiamen Second Hospital, China (approval No. 2014002). Diffusion kurtosis imaging (DKI) was used to detect 199 lesions in 156 patients with acute ischemic stroke (61 males and 95 females), mean age 63.15 ± 12.34 years. A total of 199 lesions were located in the periventricular white matter (n = 52), corpus callosum (n = 14), cerebellum (n = 29), basal ganglia and thalamus (n = 21), brainstem (n = 21) and gray-white matter junctions (n = 62). Percentage changes of apparent diffusion coefficient (ΔADC) and DKI-derived indices (fractional anisotropy [ΔFA], mean diffusivity [ΔMD], axial diffusivity [ΔD_a], radial diffusivity ΔD_r, mean kurtosis [ΔMK], axial kurtosis [ΔK_a], and radial kurtosis [ΔK_r]) of each lesion were computed relative to the normal contralateral region. The results showed that (1) there was no significant difference in ΔADC, ΔMD, ΔD_a or ΔD_r among almost all locations. (2) There was significant difference in ΔMK among almost all locations (except basal ganglia and thalamus vs. brain stem; basal ganglia and thalamus vs. gray-white matter junctions; and brainstem vs. gray-white matter junctions. (3) The degree of change in diffusional kurtosis in descending order was as follows: corpus callosum > periventricular white matter > brainstem > gray-white matter junctions > basal ganglia and thalamus > cerebellum. In conclusion, DKI could reveal the differences in microstructure changes among various locations affected by acute ischemic stroke, and performed better than diffusivity among all groups.

A Meta-Analysis of the Association between Microrna-196A2 and Risk of Ischemic Stroke and Coronary Artery Disease in Asian Population

OBJECT

Single nucleotide polymorphisms (SNPs) of small non-coding RNAs (sncRNAs) that affect the sncRNA function and target gene expression to mediate the risk of certain diseases. The association between the miR-196a2 rs11614913 and ischemic stroke (IS) and coronary artery disease (CAD) is still conflicting and inconclusive. This meta-analysis aimed at analysing studies which have been done so far to get a more precise assessment of the association between the mutation and these two diseases.

METHODS

Electronic databases dated up to April 2018 were searched, retrieved and used. Revman 5.2 software and STATA version 12.0 were used for statistical analysis. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to identify any potential associations. Heterogeneity, publication bias and sensitivity analysis were conducted to measure the robustness of our findings.

RESULTS

The overall meta-analysis results showed that miR-196a2 rs11614913 T > C polymorphism was significantly associated with CAD risk in certain genetic models, as well as in subgroup analysis (CC versus TT, OR = .43, 95%CI = .39-.47, P < .00001). However, no significant association was detected between the miR-196a2 rs11614913 T > C and IS risk in all genetic models.

CONCLUSIONS

Our study suggests that miR-196a2 rs11614913 T > C may contribute to CAD susceptibility but further well-designed studies with larger sample size and comprehensive data are needed to confirm our findings and provide a profound conclusion.

The combined effects of cardiovascular disease related SNPs on ischemic stroke

PURPOSE

Previous studies have revealed multiple common variants associated with known risk factors for cardiovascular disease (CVD). Ischemic stroke (IS) and CVD share several risk factors with each having substantial heritability. We aimed to generate a multi-locus genetic risk score (GRS) for IS based on CVD related SNPs to evaluate their combined effects on IS.

METHODS

A total of 851 patients and 977 controls were selected from Beijing, Tianjin, Shandong, Shanxi, Shaanxi and Heilongjiang communities. The candidate genes were genotyped by PCR-hybridization. Information about demographic factors, history of disease (such as hypertension), and lifestyle was obtained using structured questionnaires. A GRS model weighted by the absolute value of regression coefficient β was established to comprehensively assess the association between candidate SNPs and IS. Using the area under the receiver operating characteristic curve (AUC) to evaluate the value of GRS on predicting IS.

RESULTS

The GRS of cases was 2.87 ± 0.28, which was significantly higher than controls' GRS (2.78 ± 0.30) (P < 0.000). With the increase of the GRS, the risk of IS became higher (P_trend < 0.000). Subjects in the top quartile of the GRS had about 1.9-fold increased risk of IS compared with subjects in the lowest quartile (OR _adjusted = 1.880, 95%CI = 1.442-2.452, P < 0.000). The AUC = 0.580, P < 0.000.

CONCLUSION

13 CVD related SNPs had combined effects on IS. The GRS of cases was significantly higher than controls' GRS. As the GRS increased, the risk of IS increased. The GRS model has some value for the prediction of IS.

The HindIII and PvuII polymorphisms of lipoprotein lipase (LPL) gene reduce the risk of ischemic stroke (IS): A meta-analysis

BACKGROUND

Lipoprotein lipase (LPL) polymorphisms were suggested to be the risk factor for ischemic stroke (IS). However, controversial results were obtained. Our objective was to investigate the association of LPL polymorphisms at Ser447Ter, HindIII (+/-), and PvuII (+/-) with IS risk.

METHODS

Literatures search were carried out on databases: PubMed, Web of science, the Cochrane database of system reviews, Chinese National Knowledge Infrastructure, and Embase. Pooled odds ratio (OR) with 95% confidence interval (CI) was calculated to detect the relationship between LPL polymorphisms and the risk of IS.

RESULTS

No significant association was detected between LPL Ser447Ter and IS in allelic, dominant, or recessive models (P > .05). Significant lower frequencies of allelic and dominant models of LPL HindIII (+/-) and PvuII (+/-) in cases were detected (HindIII (+/-): allelic model: P = .0002, OR[95%CI] = 0.80 [0.71, 0.90]; dominant model: P = 0.003, OR[95%CI] = 0.80 [0.69, 0.92]; PvuII (+/-): allelic model: P < 0.0001, OR[95%CI] = 0.75[0.65-0.86]; dominant model: P = 0.02, OR[95%CI] = 0.67[0.48-0.93]). And the recessive model of PvuII (+/-) was significantly associated with the IS risk (P = .01, OR[95%CI] = .71[0.55-0.93]). Subgroup analysis stratified by ethnicity showed that the frequencies of allelic, dominant, and recessive models of HindIII (+/-), as well as dominant model of PvuII (+/-) were significant lower in Asian cases (HindIII (+/-): allelic model: P < .00001, OR[95%CI] = 0.69 [0.59, 0.79]; dominant model: P < .0001, OR[95%CI] = 0.69 [0.58, 0.83]; recessive model: P = .005, OR[95%CI] = 0.66 [0.50, 0.89]; PvuII (+/-): dominant model: P = .0008, OR[95%CI] = 0.66 [0.51-0.84]), but not in Caucasian cases (P > .05). In addition, the frequencies of allelic and recessive models of PvuII (+/-) significantly decreased in Caucasian cases (P < .05).

CONCLUSION

the HindIII (+/-) and PvuII (+/-), but not the Ser447Ter might be the protective factors for IS.

DNA Methylation in Stroke. Update of Latest Advances

Epigenetic modifications are hereditable and modifiable factors that do not alter the DNA sequence. These epigenetic factors include DNA methylation, acetylation of histones and non-coding RNAs. Epigenetic factors have mainly been associated with cancer but also with other diseases and conditions such as diabetes or obesity. In addition, epigenetic modifications could play an important role in cardiovascular diseases, including stroke. We review the latest advances in stroke epigenetics, focusing on DNA methylation studies and the future perspectives in this field.

Association of SAA gene polymorphism with ischemic stroke in northern Chinese Han population

BACKGROUND

Serum amyloid A protein (SAA) is known as an inflammatory factor and an apolipoprotein that can replace apolipoprotein A-I/II components as the major apolipoprotein of high-density lipoprotein (HDL), which is related to atherosclerosis. The present study is aimed to evaluate whether the SAA gene polymorphism is involved in ischemic stroke in northern Chinese Han population.

METHODS

In a case-control study, the participants included 396 patients (239 males, 157 females) with ischemic stroke and 360 healthy subjects (211 males, 149 females). The rs12218 polymorphism of the SAA gene was analyzed by polymerase chain reaction and restriction fragment length polymorphism, while the rs2468844 polymorphism of the SAA gene was analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

RESULTS

The frequencies of the CC genotype and the C allele of rs12218 were higher in participants with ischemic stroke than in the control group (P=0.020 in males, P=0.001 in large-artery atherosclerosis group, LAA). The frequencies of the AG genotype and the G allele of rs2468844 were higher in participants with ischemic stroke than in the control group (P=0.040 in males, P=0.011 in large-artery atherosclerosis group). Multiple logistic regression analysis revealed the significance of the rs12218 in males and in large-artery atherosclerosis group after adjustment for confounding factors.

CONCLUSION

The rs12218 polymorphism of the SAA gene was associated with ischemic stroke in males and in patients with large-artery atherosclerosis group in northern Chinese Han population.

Interactions among Variants in Eicosanoid Genes Increase Risk of Atherothrombotic Stroke in Chinese Populations

BACKGROUND

Eicosanoids are lipid mediators that may play a role in ischemic stroke (IS). However, the association of variants in eicosanoid genes and these interactions with IS risk has not been investigated. The aim of the present study was to investigate the association of 11 variants in eicosanoid genes with IS and to determine whether these gene-gene interactions increase the risk of IS.

METHODS

Eleven variants in prostaglandin H synthase-1 (PTGS1), PTGS2, thromboxane A2 synthase (TBXAS1), prostacyclin synthase (PTGIS), and prostaglandin E synthase (PTGES) genes were examined using mass spectrometry method in 297 patients with atherothrombotic stroke and 291 controls. Gene-gene interactions were analyzed using generalized multifactor dimensionality reduction (GMDR) method. Platelet aggregation and platelet-leukocyte aggregates were measured on admission.

RESULTS

There were no significant differences in the genotype distributions of the 11 variants between patients and controls. However, GMDR analysis showed a significant gene-gene interaction among rs20417, rs5602, and rs41708, which scored 10 for cross-validation consistency and 9 for the sign test (P = .014). Logistic regression analysis showed that high-risk interaction among rs20417, rs5602, and rs41708 was an independent risk factor for atherothrombotic stroke (OR = 2.45, 95% CI: 1.33-3.27, P = .019). The high-risk interactive genotypes were associated with higher platelet aggregation and platelet-leukocyte aggregates.

CONCLUSIONS

PTGS2 rs20417, PTGIS rs5602, and TBXAS1 rs41708 three-locus interactions may confer a higher risk for atherothrombotic stroke. The combinatorial analysis used in this study may be helpful to elucidate complex genetic risk for IS.

No Association Between Single-Nucleotide Polymorphism 56 (SNP56) in Phosphodiesterase 4D (PDE4D) Gene and Susceptibility to Ischemic Stroke: A Meta-Analysis of 15 Studies

Background

Recent studies demonstrated that polymorphisms in the PDE4D gene were associated with several processes involved in the occurrence of ischemic stroke (IS). The association between specific PDE4D single-nucleotide polymorphism 56 (SNP56) and IS risk was initially identified via genome-wide association studies (GWAS), although the GWAS in different populations produced inconclusive results. Thus, we performed a meta-analysis to better explain the association between PDE4D SNP56 and IS risk.

Material/Methods

A literature search was conducted using PubMed, Embase, and Web of Science up to June 1, 2015. A fixed-effects or random-effects model was used to calculate the pooled odds ratios (ORs) based on the results from the heterogeneity tests.

Results

Finally, we performed a meta-analysis of 15 studies, involving 8731 IS patients and 10,756 controls. The results showed nonsignificant association between PDE4D SNP56 and IS risk (T vs. A: OR=1.01, 95%CI=0.88–1.15, P=0.90). Similarly, in the subgroup analysis by ethnicity, no significant association was observed in Asian (T vs. A: OR=1.08, 95%CI=0.80–1.44, P=0.62) or European (T vs. A: OR=0.96, 95%CI=0.86–1.08, P=0.54) population. Moreover, funnel plots and Egger regression testing showed no evidence of publication bias.

Conclusions

In summary, current evidence suggested that PDE4D SNP56 might not be associated with an increased susceptibility to IS. However, this conclusion needs further validation by well-designed studies with large sample sizes.

Association of Genetic Polymorphisms of Renin-Angiotensin-Aldosterone System-Related Genes with Arterio-Venous Fistula Malfunction in Hemodialysis Patients

Hemodialysis (HD) is the most commonly-used renal replacement therapy for patients with end-stage renal disease worldwide. Arterio-venous fistula (AVF) is the vascular access of choice for HD patients with lowest risk of infection and thrombosis. In addition to environmental factors, genetic factors may also contribute to malfunction of AVF. Previous studies have demonstrated the effect of genotype polymorphisms of angiotensin converting enzyme on vascular access malfunction. We conducted a multicenter, cross-sectional study to evaluate the association between genetic polymorphisms of renin-angiotensin-aldosterone system and AVF malfunction. Totally, 577 patients were enrolled. Their mean age was 60 years old and 53% were male. HD patients with AVF malfunction had longer duration of HD (92.5 ± 68.1 vs. 61.2 ± 51.9 months, p < 0.001), lower prevalence of hypertension (44.8% vs. 55.3%, p = 0.025), right-sided (31.8% vs. 18.4%, p = 0.002) and upper arm AVF (26.6% vs. 9.7%, p < 0.001), and higher mean dynamic venous pressure (DVP) (147.8 ± 28.3 vs. 139.8 ± 30.0, p = 0.021). In subgroup analysis of different genders, location of AVF and DVP remained significant clinical risk factors of AVF malfunction in univariate and multivariate binary logistic regression in female HD patients. Among male HD patients, univariate binary logistic regression analysis revealed that right-side AVF and upper arm location are two important clinical risk factors. In addition, two single nucleotide polymorphisms (SNPs), rs275653 (Odds ratio 1.90, p = 0.038) and rs1492099 (Odds ratio 2.29, p = 0.017) of angiotensin II receptor 1 (AGTR1), were associated with increased risk of AVF malfunction. After adjustment for age and other clinical factors, minor allele-containing genotype polymorphisms (AA and CA) of rs1492099 still remained to be a significant risk factor of AVF malfunction (Odds ratio 3.63, p = 0.005). In conclusion, we demonstrated that rs1492099, a SNP of AGTR1 gene, could be a potential genetic risk factor of AVF malfunction in male HD patients.

Interaction Between CYP4F2 rs2108622 and CPY4A11 rs9333025 Variants Is Significantly Correlated with Susceptibility to Ischemic Stroke and 20-Hydroxyeicosatetraenoic Acid Level

AIMS

To investigate the association of four variants of two CYP ω-hydroxylase genes and 20-hydroxyeicosatetraenoic acid (HETE) levels with ischemic stroke (IS) and whether gene-gene interactions between these genes increase the risk of IS.

METHODS

Three hundred ninety-six patients with IS and 378 controls were genotyped for rs2269231, rs9333025, rs2108622, and rs3093135. Gene-gene interactions were analyzed using generalized multifactor dimensionality reduction (GMDR) methods. The 20-HETE levels was measured in 218 IS patients and 126 controls.

RESULTS

The frequency of the GG genotype of rs9333025 was significantly higher in IS patients than in controls (p < 0.001). The GMDR analysis showed a significant gene-gene interaction between rs9333025 and rs2108622 (p = 0.0116). This gene-gene interaction predicted a significantly higher risk of IS in individuals carrying the genotypes of rs9333025 GG and rs2108622 GG (odds ratio = 1.92, 95% confidence interval = 1.12-4.26, p = 0.007). The plasma levels of 20-HETE were significantly higher in IS patients than in controls, and IS patients carrying the genotype combination of rs9333025 GG and rs2108622 GG had higher 20-HETE levels than IS patients with other combinations of the two variants.

CONCLUSION

CYP4A1l rs9333025 GG and CYP4F2 rs2108622 GG two-loci interaction significantly increases the risk for IS and an elevated 20-HETE level.

Association Between Single-Nucleotide Polymorphism (SNP) in miR-146a, miR-196a2, and miR-499 and Risk of Ischemic Stroke: A Meta-Analysis

Background

The association between 3 well known SNPs – miR-146a C/G (rs2910164), miR-196a2 T/C (rs11614913), and miR-499 A/G (rs3746444) – in pre-miRNA sequences and ischemic stroke (IS) are still conflicting and inconclusive. This meta-analysis aimed to pool previous studies get a more precise assessment of the association between these 3 SNPs and the risk of IS.

Material/Methods

Relevant studies were searched in online databases. The strength of the association between the SNPs and IS were estimated by pooling odds ratios (OR) and 95% confidence intervals (CI) using Review Manager (version 5.3).

Results

Rs2910164 C allele was associated with lower IS risk. But this trend was only observed in Koreans under the allele model (OR=0.81, 95% CI=0.68–0.95, p=0.009), dominant model (OR=0.68, 95% CI=0.50–0.93, p=0.02), recessive model (OR=0.79, 95% CI=0.63–1.00, p=0.05), and homozygous model (OR=0.63, 95%CI=0.45–0.88, p=0.007). Rs11614913 T allele might be associated with higher IS risk under the dominant model (OR=1.45, 95% CI=1.19–1.78, p=0.0003), while rs3746444 A allele might be associated with decreased IS risk under the homozygous model (OR=0.48, 95% CI=0.23–0.98, p=0.04) only in Chinese, but not in Koreans.

Conclusions

Although the 3 SNPs might be associated with IS, the association varied significantly in different countries.

Phosphodiesterase4D (PDE4D)--A risk factor for atrial fibrillation and stroke?

Mutations in the gene encoding phosphodiesterase 4D (PDE4D) enzyme are associated with ischemic stroke; however the functional implications of such mutations are not well understood. PDE4D is part of a complex protein family modulating intracellular signalling by cyclic nucleotides. The PDE4 family includes subtypes A-D, all of which show unique intracellular, cellular and tissue distribution. PDE4D is the major subtype expressed in human atrial myocytes and involved in the pathophysiology of arrhythmias, such as atrial fibrillation. The PDE4D enzyme hydrolyses cyclic adenosine monophosphate (cAMP). Though diverging results are reported, several population based studies describe association of various PDE4D single nucleotide polymorphisms (SNP) with cardio-embolic stroke in particular. Functionally, a down regulation of PDE4D variants has been reported in stroke patients. The anti-inflammatory and vasodilator properties of PDE4 inhibitors make them suitable for treatment of stroke and cardiovascular disease. PDE4D has recently been suggested as factor in atrial fibrillation. This review summarizes the possible function of PDE4D in the brain, heart, and vasculature. Further, association of the described SNPs, in particular, with cardioembolic stroke, is reviewed. Current findings on the PDE4D mutations suggest functionality involves an increased cardiac risk factor as well as augmented risk of atrial fibrillation.

An Inflammatory Polymorphisms Risk Scoring System for the Differentiation of Ischemic Stroke Subtypes

Inflammation has been associated with atherothrombotic stroke and recently with cardioembolic stroke. Different genetic risk factors have been specifically associated with the subtypes of ischemic stroke (cardioembolic, atherothrombotic, and lacunar). However, there are no studies that have generated genetic risk scores for the different subtypes of ischemic stroke using polymorphisms associated with inflammation.

METHODS

We have analyzed 68 polymorphisms of 30 inflammatory mediator genes in 2,685 subjects: 1,987 stroke cases and 698 controls. We generated a genetic scoring system with the most significant polymorphisms weighted by the odds ratio of every polymorphism and taken into consideration the stroke subtype.

RESULTS

Three polymorphisms, rs1205 (CRP gene), rs1800779, and rs2257073 (NOS3 gene), were associated with cardioembolic stroke (p value <0.05). The score generated was only associated with the cardioembolic stroke subtype (p value: 0.001) and was replicated in an independent cohort (p value: 0.017). The subjects with the highest score presented a cardioembolic stroke in 92.2% of the cases (p value: 0.002).

CONCLUSION

The genetics of inflammatory markers is more closely associated with cardioembolic strokes than with atherothrombotic or lacunar strokes. The genetic risk scoring system could be useful in the prediction and differentiation of ischemic stroke; however, it might be specific to particular ischemic stroke subtypes.

Cytochrome 4A11 Genetic Polymorphisms Increase Susceptibility to Ischemic Stroke and Associate with Atherothrombotic Events After Stroke in Chinese

To evaluate the associations between four single-nucleotide polymorphisms (SNPs) in CYP4A11 and CYP4F2 and ischemic stroke (IS), and between these variants and atherothrombotic events after stroke. IS patients (n=396) and controls (n=378) were genotyped for two CYP4A11 SNPs (rs2269231 and rs9333025) and two CYP4F2 SNPs (rs2108622 and rs3093135). Patients were followed up for 12 months after the stroke for the atherothrombotic events. The frequency of the rs9333025 GG genotype was significantly higher in IS patients than in controls. Logistic regression analysis showed that the presence of rs9333025 GG in patients was associated with significantly higher risk of IS. Cox regression analysis revealed that the rs9333025 GG genotype was an independent risk factor for atherothrombotic events after stroke. The rs9333025 GG genotype increases patients' susceptibility to IS and is associated with high frequencies of atherothrombotic events in stroke patients.

Genetic polymorphisms of ALOX5AP and CYP3A5 increase susceptibility to ischemic stroke and are associated with atherothrombotic events in stroke patients

BACKGROUND

The contributions of gene-gene interactions to pathogenesis of stroke remain largely elusive. The present study was designed to investigate the associations between genetic variations and ischemic stroke risk, the roles of gene-gene interactions in ischemic stroke, and their associations with atherothrombotic events.

METHODS

Among 396 patients with ischemic stroke and 378 controls, we examined 8 variants from 5 genes, including ALOX5AP-SG13S32 (rs9551963), SG13S42 (rs4769060), SG13S89 (rs4769874), SG13S114 (rs10507391), EPHX2 G860A (rs751141), CYP2C9*2 C430T (rs1799853), CYP2C9*3 A1075C (rs1057910), and CYP3A5 A6986G (rs776746), using matrix-assisted laser desorption/ionization time of flight mass spectrometry. Gene-gene interactions were determined by the generalized multifactor dimensionality reduction (GMDR) method. All ischemic stroke patients were followed up 12 months for atherothrombotic events, including recurrent ischemic stroke and other vascular events.

RESULTS

Single-gene variant analysis showed no significant differences in the genotype distributions of the 8 variants between the 2 groups. However, the GMDR analysis showed a significant interaction between rs10507391 and rs776746, in those cases carrying rs10507391 AA and rs776746 GG, the risk of ischemic stroke increased by 2.014 times (95% confidence interval [CI], 1.896-6.299; P = .006), and the atherothrombotic events occurred more frequently in those patients during follow-up period (P < .001). Multiple Cox regression analysis showed that the interaction between rs10507391 AA and rs776746 GG was an independent risk factor for atherothrombotic events (relative risk = 2.921; 95% CI, 1.118-7.012; P = .008).

CONCLUSIONS

The interaction between rs10507391 and rs776746 increases the susceptibility to ischemic stroke and is associated with atherothrombotic events in stroke patients.

The CELSR1 polymorphisms rs6007897 and rs4044210 are associated with ischaemic stroke in Chinese Han population

BACKGROUND

Recently, CELSR1 was identified by genome-wide association studies (GWAS) as a susceptibility gene for ischaemic stroke (IS) in Japanese individuals.

AIM

The goal was to examine whether CELSR1 variants are associated with IS in the Chinese Han population.

SUBJECTS AND METHODS

This study genotyped two single nucleotide polymorphisms (SNPs) of CELSR1, rs6007897 and rs4044210, in a Chinese sample of 569 IS cases and 581 controls and assessed their genotype and allele associations with IS.

RESULTS

The results showed that rs6007897 and rs4044210 variants of CELSR1 were significantly (p < 0.01) associated with IS. These associations remained after adjustment for age, gender, smoking status, hypertension, diabetes mellitus and hypercholesterolemia. In addition, a significant association was observed of rs6007897 and rs4044210 of CELSR1 with large artery atherosclerosis (LAA), a sub-type of IS (p < 0.01).

CONCLUSION

Taken together, the present study has proven for the first time that CELSR1 is a susceptibility gene for IS in the Chinese Han population, especially for LAA.

Genetic variants in C-reactive protein and ischemic stroke susceptibility

Considerable discrepancies in the previously reported associations of the C-reactive protein (CRP) gene variants and ischemic stroke (IS) risk prompted us to perform this meta-analysis. We selected the fixed effects Mantel-Haenszel method to estimate the risk of IS [OR (odds ratio) along with its 95 % CI (confidence interval)] in relation to the CRP variants (-717 A > G, 1444 C > T). Heterogeneity test, influence analysis and publication bias test were appropriately performed using respective methods. We analyzed 1,926 IS patients and 2,678 controls and found the -717 A > G variant was not significantly associated with overall IS risk. Subsequent analysis of the 1444 C > T variant involving 3,278 samples similarly revealed no significant association with IS. There was no substantial heterogeneity or publication bias in this analysis. Our meta-analysis may provide first evidence showing that genetic variants within the CRP locus are unlikely to modulate risk of IS.

miR-146a and miR-196a2 polymorphisms in patients with ischemic stroke in the northern Chinese Han population

MicroRNAs are endogenous non-coding RNAs about 22 nucleotides in length that can repress the expression of proteins by binding to the 3'-untranslated regions of target messenger RNAs. We hypothesized that polymorphisms in miR-146a and miR-196a2 are associated with risk of ischemic stroke in the northern Chinese Han population. In a case-control study of 368 ischemic stroke patients and 381 control subjects that were frequency matched by age and gender, we genotyped two single nucleotide polymorphisms (rs11614913 in miR-196a2 and rs2910164 in miR-146a) using polymerase chain reaction-ligation detection reaction. The frequencies of the rs2910164 CC genotype and C allele within miR-146a were not significantly different in patients with ischemic stroke compared with those in the healthy control group. In subgroup meta-analysis, rs2910164 in miR-146a and large-artery atherosclerosis, rather than small-vessel disease, showed the significant association under the dominant model (CC vs CG+GG, OR 1.694; 95 % CI 1.199-2.395 p = 0.003). After adjusting for confounding risk factors of ischemic stroke by logistic regression analysis, this significant correlation remained. In addition, the distributions of the miR-196a2 genotypes and alleles were not statistically different between ischemic stroke and healthy groups. We also did not find any significant association from stroke subtypes. The CC genotype and C allele of rs2910164 within miR-146a are associated with an increased incidence of large-artery atherosclerotic stroke in the northern Chinese Han population. This study indicates that miR-146a (rs2910164) might contribute to ischemic stroke susceptibility in the northern Chinese Han population.

G894T endothelial nitric oxide synthase polymorphism and ischemic stroke in Morocco

Nitric oxide plays a major role in the regulation of cerebral blood flow and loss of its function leads to alteration of the vascular relaxation given its central role in the physiology of the vascular system. G894T eNOS polymorphism could have adverse effects on the expression and activity of endothelial nitric oxide synthase, which can result in functional impairment of the endothelium and contribute to the development of ischemic stroke in the different models of transmission. In this study, genotyping with PCR-RFLP and HRM (high resolution melting) methods were conducted on 165 ischemic stroke patients as well as 182 controls. The goal here was to compare genotyping with PCR-RLFP primer sequences of eNOS gene (size < 300 bp) to HRM. Our data suggests a statistically significant association between G894T eNOS polymorphism and ischemic stroke in recessive, dominant and additive models with P < 0.05 and odds ratio of 2.68 (1.08-6.70), 1.78 (1.16-2.73), and 1.71 (1.21-2.43) respectively. In sum, although the sample size is relatively small, it suggests that G894T eNOS polymorphism could be a potentially important genetic marker of ischemic stroke in the Moroccan population. Future studies should be conducted in this direction taking into consideration the functional activity of eNOS.

Association of pregnancy-associated plasma protein-A gene polymorphism with ischemic stroke in northern Chinese Han population

OBJECTIVES

The pregnancy-associated plasma protein-A (PAPP-A), belonging to the metalloproteinase superfamily, plays an important role in destabilization of atherosclerotic plaques. The aim of this study is to evaluate whether PAPP-A gene polymorphism is associated with the risk of ischemic stroke (IS) in northern Chinese Han populations.

METHODS

A total of 368 patients with IS and 374 aged-matched healthy controls in a Chinese Han population were included in the case-control study. The single-nucleotide polymorphism (SNP) IVS6+95 (rs13290387) in the PAPP-A gene was analyzed by the polymerase chain reaction-ligation detection reaction (PCR-LDR) method.

RESULTS

Compared with the GG+CG genotype, the frequencies of the CC genotype of IVS6+95 (rs13290387) in the patients with IS were significantly higher than those in the controls (P  =  0·026). After adjusting the confounding risk factors of IS (age, gender, smoking, alcohol drinking, hypertension, diabetes mellitus, and hyperlipidemia) by the multivariate logistic analysis, this significant correlation still remained (P  =  0·010).

DISCUSSION

The CC genotype of IVS6+95 (rs13290387) was associated with increased incidence of IS in northern Chinese Han populations. This is an initial study to indicate that PAPP-A (rs13290387) might contribute to IS susceptibility in northern Chinese Han populations.

Genetic variants on chromosome 10q11.21 are associated with ischemic stroke in the northern Chinese Han population

Genome-wide association studies have revealed two loci (rs1746048 and rs501120) on chromosome 10q11.21 associated with atherosclerosis. The genetic variants are related to chemokine (C-X-C motif) ligand 12, which has been shown to affect atherosclerosis. This study aims to explore the associations between these loci and risk of ischemic stroke in the northern Chinese Han population. A total of 368 patients with ischemic stroke and 381 healthy controls were included in the study. The single-nucleotide polymorphisms rs501120 and rs1746048 were analyzed by polymerase chain reaction-ligation detection reaction methods. Increased risk of ischemic stroke was associated with rs1746048 in a dominant mode. The CT + TT genotype of rs1746048 was represented at an increased frequency among patients with ischemic stroke. The genotype and allele frequencies of rs501120 were similar between patients with ischemic stroke and controls. However, the rs501120 CT + CC genotype and C allele were associated with an increased risk of ischemic stroke in the male subgroup. These correlations still remained after adjusting for confounding risk factors of stroke. Here, we present a study indicating that genetic variation on chromosome 10q11.21 might contribute to stroke susceptibility.

COL4A2 mutation associated with familial porencephaly and small-vessel disease

Familial porencephaly, leukoencephalopathy and small-vessel disease belong to the spectrum of disorders ascribed to dominant mutations in the gene encoding for type IV collagen alpha-1 (COL4A1). Mice harbouring mutations in either Col4a1 or Col4a2 suffer from porencephaly, hydrocephalus, cerebral and ocular bleeding and developmental defects. We observed porencephaly and white matter lesions in members from two families that lack COL4A1 mutations. We hypothesized that COL4A2 mutations confer genetic predisposition to porencephaly, therefore we sequenced COL4A2 in the family members and characterized clinical, neuroradiological and biochemical phenotypes. Genomic sequencing of COL4A2 identified the heterozygous missense G1389R in exon 44 in one family and the c.3206delC change in exon 34 leading to frame shift and premature stop, in the second family. Fragmentation and duplication of epidermal basement membranes were observed by electron microscopy in a c.3206delC patient skin biopsy, consistent with abnormal collagen IV network. Collagen chain accumulation and endoplasmic reticulum (ER) stress have been proposed as cellular mechanism in COL4A1 mutations. In COL4A2 (3206delC) fibroblasts we detected increased rates of apoptosis and no signs of ER stress. Mutation phenotypes varied, including porencephaly, white matter lesions, cerebellar and optic nerve hypoplasia and unruptured carotid aneurysm. In the second family however, we found evidence for additional factors contributing to the phenotype. We conclude that dominant COL4A2 mutations are a novel major risk factor for familial cerebrovascular disease, including porencephaly and small-vessel disease with reduced penetrance and variable phenotype, which might also be modified by other contributing factors.

Asymptotic distribution for epistatic tests in case-control studies

We propose a statistical model for dissecting a multilocus genotypic value into its main (additive and dominant) effects and epistatic effects between different loci in a case-control association study. The model can discern four different kinds of epistasis, additive × additive, additive × dominant, dominant × additive, and dominant × dominant interactions. To test each kind of epistasis, a χ(2) test statistic was computed for a two by two contingency table derived from combined genotypes in both case and control groups. We derived an analytical approach for estimating the asymptotic distribution of the χ(2) test statistic for epistatic tests under the null hypothesis, with the result being consistent with that from Monte Carlo simulations. The new model was used to analyze a case-control data set for candidate gene studies of stroke, leading to the identification of several significant interactions between causal SNPs on this disease.

The I/D polymorphism of the ACE1 gene is not associated with ischaemic stroke in Spanish individuals

BACKGROUND

The angiotensin-converting enzyme 1 (ACE1) gene has been extensively studied in stroke, yet generating conflicting results. The goal of our study was thus to clarify the influence of the ACE1 on the risk of suffering an ischaemic stroke (IS).

METHODS

We genotyped the rs4341 (in linkage disequilibrium with the I/D polymorphism) of the ACE1 gene in 531 patients with IS and 549 healthy controls, and the rs1799752 (I/D polymorphism) in a subset of 68 patients with IS and 27 controls. We also performed functional studies by measuring serum ACE protein levels and enzymatic activity in 27 controls, 68 patients with IS at baseline and 35 patients with IS 24 h after onset of stroke symptoms.

RESULTS

There was no association of the ACE1 variant with IS, although it affected ACE protein levels (P = 0.001). Indeed, patients with IS showed lower ACE levels than controls in the acute phase (115.9 } 38.9 vs. 174.1 } 56.1 ng/ml, P < 0.001), but not in the chronic phase (168.2 } 51.2, P = 0.673), and ACE protein levels did not differ between IS etiologies. Similar results were found for ACE activity.

CONCLUSIONS

The D allele of the ACE1 I/D and ACE protein levels was not associated with a higher risk of IS in Spanish individuals.

CYP4F2 gene V433M polymorphism is associated with ischemic stroke in the male Northern Chinese Han population

BACKGROUND

CYP4F2 is a member of the cytochrome P450 enzymes and is responsible for metabolizing arachidonic acid to 20-hydroxyeicosatetraenoic acid (20-HETE); 20-HETE plays a role in the regulation of vascular tone in the cerebral, coronary, and renal circulation. The present study aimed to evaluate whether or not the CYP4F2 gene polymorphism V433M (rs2108622) is involved in ischemic stroke in the Northern Chinese Han population.

METHODS

In a case-control study, the participants included 302 (193 males and 109 females) patients with ischemic stroke and 350 (212 males and 138 females) healthy subjects. The V433M polymorphism of the CYP4F2 gene was analyzed by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) with the restriction enzyme PvuII.

RESULTS

The frequencies of the GG genotype and the G allele were higher in participants with ischemic stroke than in the control group (P=0.018). Multiple logistic regression analysis revealed the significance of the rs2108622 in males after adjustment for confounding factors. No difference was found in all participants and females.

CONCLUSION

The GG genotype and G allele were associated with ischemic stroke in the male Northern Chinese Han population.

Endothelial nitric oxide synthase Glu298Asp, 4b/a, and -786T>C gene polymorphisms and the risk of ischemic stroke

BACKGROUND AND PURPOSE

Endothelial nitric oxide synthase (eNOS) gene polymorphisms were associated with reduced NO production, and were evaluated as risk factors for ischemic stroke (IS). We investigated the association between eNOS gene -786T>C (promoter), 27-bp repeat 4b/4a (intron 4), and Glu298Asp (exon 7) polymorphisms with IS in 329 IS patients and 444 controls.

MATERIALS AND METHODS

Glu298Asp and -786T>C genotyping was done by PCR-RFLP, 4b/4a was assessed by PCR-ASA. The contribution of eNOS polymorphisms to IS was analyzed by haplotype and multivariate regression analysis.

RESULTS

Higher frequency of 298Asp allele was seen in IS patients (P = 1.2 x 10(-10)), which remained independently associated with IS on multivariate analysis after controlling for traditional cerebrovascular risk factors. Allele and genotype distribution of 4b/4a and -786T>C polymorphisms were comparable between patient and controls. Significantly higher prevalence of 298Asp/4b/-786T and 298Asp/4b/-786C haplotypes were seen in IS cases, thus conferring a disease susceptibility nature to these haplotypes. Multivariate regression analysis confirmed the association of 298Asp/4b/-786T and 298Asp/4b/-786C haplotypes, and in addition identified 298Asp/4a/-786T haplotype to be independently associated with IS, after controlling for traditional cerebrovascular risk factors.

CONCLUSIONS

Genetic variation at the eNOS locus represent genetic risk factor for increased susceptibility to IS.

Kalirin: a novel genetic risk factor for ischemic stroke

Cerebrovascular and cardiovascular diseases are the leading causes of death and disability worldwide. They are complex disorders resulting from the interplay of genetic and environmental factors, and may share several susceptibility genes. Several recent studies have implicated variants of the Kalirin (KALRN) gene with susceptibility to cardiovascular and metabolic phenotypes, but no studies have yet been performed in stroke patients. KALRN is involved, among others, in the inhibition of inducible nitric oxide synthase, in the regulation of ischemic signal transduction, and in neuronal morphogenesis, plasticity, and stability. The goal of the present study was to determine whether SNPs in the KALRN region on 3q13, which includes the Ropporin gene (ROPN1), predispose to ischemic stroke (IS) in a cohort of Portuguese patients and controls. We genotyped 34 tagging SNPs in the KALRN and ROPN1 chromosomal region on 565 IS patients and 517 unrelated controls, and performed genotype imputation for 405 markers on chromosome 3. We tested the single-marker association of these SNPs with IS. One SNP (rs4499545) in the ROPN1-KALRN intergenic region and two SNPs in KALRN (rs17286604 and rs11712619) showed significant (P < 0.05) allelic and genotypic (unadjusted and adjusted for hypertension, diabetes, and ever smoking) association with IS risk. Thirty-two imputed SNPs also showed an association at P < 0.05, and actual genotyping of three of these polymorphisms (rs7620580, rs6438833, and rs11712039) validated their association. Furthermore, rs11712039 was associated with IS (0.001 < P < 0.01) in a recent well-powered genomewide association study (Ikram et al. 2009). These studies suggest that variants in the KALRN gene region constitute risk factors for stroke and that KALRN may represent a common risk factor for vascular diseases.