PDE4D and ALOX5AP genetic variants and risk for Ischemic Cerebrovascular Disease in Sweden

Phosphodiesterase 4 D (PDE4D) gene polymorphisms and risk of ischemic stroke: A systematic review and meta-analysis

BACKGROUND AND PURPOSE

Studies on the relationship between Phosphodiesterase 4 D (PDE4D) gene polymorphism with the risk of ischemic stroke (IS) have shown discordant results. The present meta-analysis was aimed to clarify the relationship between PDE4D gene polymorphism with the risk of IS by estimating pooled analysis of published epidemiological studies.

METHODS

A comprehensive literature search for all the published articles was performed in various electronic databases, including PubMed, EMbase, Cochrane Library, Trip Database, Worldwide Science, CINAHL, and Google Scholar up to 22nd December 2021. Pooled Odds ratios (ORs) with 95% Confidence Intervals (CIs) under dominant, recessive, and allelic models were calculated. Subgroup analysis based on ethnicity (Caucasian vs. Asian) was performed to examine the reliability of these findings. Sensitivity analysis was also performed to detect the heterogeneity between studies. Finally, Begg's funnel plot was used to assess the potential for publication bias.

RESULTS

In our meta-analysis, we identified a total of 47 case-control studies with 20,644 ischemic stroke (IS) cases and 23,201 control subjects, including 17 studies of Caucasian descent and 30 studies of Asian descent. Our findings suggest that there was a significant relationship between SNP45 gene polymorphism and risk of IS (Recessive model: OR = 2.06, 95% CI 1.31-3.23), SNP83 overall (allelic model: OR = 1.22, 95% CI 1.04-1.42), Asian (allelic model: OR = 1.20, 95% CI 1.05-1.37), and SNP89 Asian (Dominant model: OR = 1.43, 95% CI 1.29-1.59, recessive model: OR = 1.42, 95% CI 1.28-1.58) respectively. However, no significant relationship was found between SNP32, SNP41, SNP26, SNP56, and SNP87 gene polymorphisms and risk of IS.

CONCLUSION

Findings of this meta-analysis conclude that SNP45, SNP83, and SNP89 polymorphism could be capable of increasing stroke susceptibility in Asians but not in the Caucasian population. Genotyping of SNP 45, 83, 89 polymorphisms may be used as a predictor for the occurrence of IS.

The SG13S114 polymorphism of the ALOX5AP gene is associated with ischemic stroke in Europeans: a meta-analysis of 8062 subjects

The association between ALOX5AP SG13S114 polymorphism and ischemic stroke (IS) susceptibility has extensively been investigated, especially in white populations; however, the results were inconclusive. Here, we perform a meta-analysis to clarify the effect of SG13S114 variant on the IS risk in Europeans. The Web of Science, PubMed, EMBASE, and Medline were searched up to August 1st, 2016. Data were extracted and the odd ratios (ORs) and 95% confidence intervals (CIs) were calculated by a fixed-effects or random-effects model. In total, 8 case control studies involved 8062 subjects were finally included in this meta-analysis. We observed a significantly decreased IS risk in persons carrying an A allele at the SG13S114 polymorphism compared with those with a T allele (A vs T, OR = 0.856, 95% CI = 0.797-0.919, p < 0.001). In addition, the results of sensitivity and cumulative meta-analysis indicated the robustness of our results. In addition, the publication bias was not detected using the funnel plot and Egger's tests. In summary, the present meta-analysis suggested that the A allele at the ALOX5AP SG13S114 polymorphism is a protective factor for the IS in the Europeans. In addition, further studies with large sample size are needed to validate the association, as well as in other ethnic groups.

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.

Genetic susceptibility to cerebrovascular disease

PURPOSE OF REVIEW

Cerebrovascular disease (CeVD) remains a major cause of death and a leading cause of disability worldwide. CeVD is a complex and multifactorial disease caused by the interaction of vascular risk factors, environment, and genetic factors. In the present article, we discussed genetic susceptibility to CeVD, with particular emphasis on genetic studies of the associations between lipid traits and CeVD.

RECENT FINDINGS

Several animal and clinical studies clearly defined genetic predisposition to atherosclerosis and CeVD, and particularly to ischemic stroke. Recent evidence has shown that traditional vascular risk factors explain only a small proportion of variance in atherosclerosis, suggesting that additional nontraditional factors and novel genetic determinants impact CeVD. With the help of genome-wide technology, novel genetic variants have been implicated in CeVD and lipid metabolism such as those in protein convertase subtilisin/kexin type 9 (PCSK9) gene in stroke and familial hypercholesterolemia. These studies are important as they contribute to our understanding of the genetic mechanisms underlying CeVD and to developing more effective CeVD prevention strategies.

SUMMARY

CeVD is a complex and multifactorial disease and genetics likely plays an important role in its pathogenesis. The gene-gene and gene-environment interactions of genes involved in biology of vascular disease, including the lipid metabolism are important factors for individual susceptibility to CeVD. Accounting for individual variation in genes, environment and lifestyle will bring us closer to precision medicine, which is an emerging and recently introduced new approach for disease treatment and prevention in clinical practice.

Mammalian lipoxygenases and their biological relevance

Lipoxygenases (LOXs) form a heterogeneous class of lipid peroxidizing enzymes, which have been implicated not only in cell proliferation and differentiation but also in the pathogenesis of various diseases with major public health relevance. As other fatty acid dioxygenases LOXs oxidize polyunsaturated fatty acids to their corresponding hydroperoxy derivatives, which are further transformed to bioactive lipid mediators (eicosanoids and related substances). On the other hand, lipoxygenases are key players in the regulation of the cellular redox homeostasis, which is an important element in gene expression regulation. Although the first mammalian lipoxygenases were discovered 40 years ago and although the enzymes have been well characterized with respect to their structural and functional properties the biological roles of the different lipoxygenase isoforms are not completely understood. This review is aimed at summarizing the current knowledge on the physiological roles of different mammalian LOX-isoforms and their patho-physiological function in inflammatory, metabolic, hyperproliferative, neurodegenerative and infectious disorders. This article is part of a Special Issue entitled "Oxygenated metabolism of PUFA: analysis and biological relevance".

Interrelationships between ALOX5AP polymorphisms, serum leukotriene B4 level and risk of acute coronary syndrome

BACKGROUND

We investigated the relationships between the ALOX5AP gene rs10507391 and rs4769874 polymorphisms, serum levels of leukotriene (LT) B4, and risk of acute coronary syndrome (ACS).

METHODS

A total of 709 participants, comprising 508 ACS patients (ACS group) and 201 noncoronary artery disease patients with chest pain (control group) were recruited from the Han population of the Changwu region in China. Two polymorphic loci were genotyped using polymerase chain reaction and restriction fragment length polymorphism analysis. Serum LTB4 level was determined by enzyme-linked immunosorbent assay.

RESULTS

Serum LTB4 levels were significantly higher (P<0.001) in the ACS group (median/interquartile range, 470.27/316.32 pg/ml) than in the control group (233.05/226.82 pg/ml). No statistical differences were observed between genotype, allele and haplotype frequencies for the tested loci in either the ACS group or the control group, even after adjustments were made for conventional risk factors by multivariate logistic regression. This suggests there is no association between the ALOX5AP rs10507391 and rs4769874 polymorphisms and ACS risk. Elevated serum LTB4 level was closely linked to ACS risk, and may be independent of traditional risk factors as a risk factor for ACS (P<0.001). There was no significant association between serum LTB4 levels and the two variants in either the ACS group or the control group.

CONCLUSIONS

Rs10507391, rs4769874 and its haplotypes in ALOX5AP are unrelated to ACS risk in the Chinese Han population of Changwu, but elevated serum LTB4 level is strongly associated with ACS risk. Serum LTB4 level is not subject to the influence of either the rs10507391, rs4769874 or the haplotype.

The arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene SG13S114 polymorphism and ischemic stroke in Chinese population: a meta-analysis

Previous studies have indicated that the arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene SG13S114 polymorphism is associated with risk of ischemic stroke (IS), but the results remain inconclusive even in Chinese population. A meta-analysis of 10 case-control studies was conducted on the relationship between ALOX5AP SG13S114 polymorphism and susceptibility to IS in Chinese population published domestically and abroad from September 2007 to December 2012. Data were extracted by two authors and pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. Meta-analysis results showed that the significant association between SG13S114 variant and IS was found under the allelic (OR=0.87, 95% CI: 0.80-0.96, P=0.004), dominant (OR=0.75, 95% CI: 0.62-0.92, P=0.005), and recessive (OR=0.89, 95% CI: 0.82-0.97, P=0.005) genetic models in Chinese population. In subgroup meta-analysis, SG13S114 variant and atherothrombotic stroke, rather than lacunar stroke, showed the significant association under the allelic (OR=0.86, 95% CI: 0.80-0.92, P<0.0001), dominant (OR=0.72, 95% CI: 0.57-0.91, P=0.006), and recessive (OR=0.86, 95% CI: 0.78-0.95, P=0.002) models. ALOX5AP SG13S114 polymorphism is associated with susceptibility to IS in Chinese population.

Variants of the arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene and risk of ischemic stroke in Han Chinese of eastern China

Variants of the arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene have been suggested to play an important role in the pathogenesis of atherosclerosis and ischemic stroke. This study was aimed to explore the association of ALOX5AP variants with ischemic stroke risk in Han Chinese of eastern China. A total of 690 ischemic stroke cases and 767 controls were recruited. The subjects were further subtyped according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria. On the basis of that, two polymorphisms of the ALOX5AP gene (rs10507391 and rs12429692) were determined by TaqMan genotyping assay. In addition, plasma leukotriene B4 (LTB4) levels were analyzed in these subjects. There was no evidence of association between the two variants of ALOX5AP and the risk of ischemic stroke or its TOAST-subtypes. Haplotype analysis and stratification analysis according to sex, age, body mass index, hypertension, and diabetes also showed negative association. Analysis of LTB4 levels in a subset of cases and controls revealed that LTB4 levels were significantly higher in ischemic stroke cases than in the controls (70.06±14.75 ng/L vs 57.34±10.93 ng/L; P = 0.000) and carriers of the T allele of the rs10507391 variant were associated with higher plasma LTB4 levels (P = 0.000). The present study suggests there is no association of the two polymorphisms in the ALOX5AP gene with ischemic stroke risk in Han Chinese of eastern China.

Genetic variation in members of the leukotrienes biosynthesis pathway confers risk of ischemic stroke in Eastern Han Chinese

This study was aimed to explore the association of genetic variation in members of the leukotrienes biosynthesis pathway as potential mediators with ischemic stroke (IS) risk in Eastern Han Chinese. A case-control study of was conducted with five selected single nucleotide polymorphisms (SNPs). In the single-locus analysis, carriers of C allele of rs730012 in LTC4S were more susceptible to IS (OR, 1.28; 95% CI, 1.02-1.60; P=0.033). Under the recessive genetic model, ALOX5 rs2029253 variant reduced IS risk (adjusted OR, 0.78; 95% CI, 0.60-1.00; P=0.048) while LTA4H rs6538697 and LTC4S rs730012 variants increased (adjusted OR, 1.66; 95% CI, 1.04-2.64; P=0.032 and adjusted OR, 3.63; 95% CI, 1.01-13.05; P=0.048, respectively). However, there was no evidence of association between all five SNPs and IS risk after correction for multiple testing. In combined analysis of multiple genes and loci, individuals with ALOX5AP rs12429692 T allele, ALOX5 rs2029253 A allele, and LTA4H rs6538697 C allele suggested a significantly increased susceptibility to IS (adjusted OR, 1.70; 95% CI, 1.07-2.69; P=0.024). The present study suggested gene-gene interactions in leukotrienes pathway could exert influences on the risk of IS.

Association of ALOX5AP gene single nucleotide polymorphisms and cerebral infarction in the Han population of northern China

BACKGROUND

To explore the association of ALOX5AP single nucleotide polymorphisms (SNPs) and haplotype with the occurrence of cerebral infarction in the Han population of northern China.

METHODS

Blood samples were collected from 236 patients of Han ancestry with a history of cerebral infarction and 219 healthy subjects of Han ancestry with no history of cerebral infarction or cardiovascular disease. Applied Biosystems(®) TaqMan(®) SNP Genotyping Assays for SNP genotyping were used to determine the genotypes of 7 ALOX5AP SNP alleles (rs4073259, rs4769874, rs9315050, rs9551963, rs10507391, rs9579646, and rs4147064).

RESULTS

One SNP allele (A) of rs4073259 was significantly associated with development of cerebral infarction (P = 0.049). In comparison to control groups, haplotype rs9315050&rs9551963 AAAC [OR (95% CI) = 1.53 (1.02-2.29)], and genotypes rs4147064 CT [OR (95% CI) = 1.872 (1.082-3.241)], and rs9551963 AC [OR (95% CI) = 2.015 (1.165-3.484)] increased the risk of cerebral infarction in patients with hypertension. Genotype rs9579646 GG [OR (95% CI) = 2.926 (1.18-7.251)] increased the risk of, while rs4073259 GG [OR (95% CI) = 0.381 (0.157-0.922)] decreased the risk of cerebral infarction in patients with diabetes.

CONCLUSION

These results suggest the ALOX5AP SNP A allele in rs4073259 and genotype rs9579646 GG, rs9551963 AC, and haplotype rs9315050 & rs9551963 AAAC were associated with an increased risk of ischemic stroke in the Han population, while rs4073259 GG was associated with a decreased risk.

Genetics of ischemic stroke, stroke-related risk factors, stroke precursors and treatments

Stroke remains a leading cause of death worldwide and the first cause of disability in the western world. Ischemic stroke (IS) accounts for almost 80% of the total cases of strokes and is a complex and multifactorial disease caused by the combination of vascular risk factors, environment and genetic factors. Investigations of the genetics of atherosclerosis and IS has greatly enhanced our knowledge of this complex multifactorial disease. In this article we sought to review common single-gene disorders relevant to IS, summarize candidate gene and genome-wide studies aimed at discovering genetic stroke risk factors and subclinical phenotypes, and to briefly discuss pharmacogenetics related to stroke treatments. Genetics of IS is, in fact, one of the most promising research frontiers and genetic testing may be helpful for novel drug discoveries as well as for appropriate drug and dose selection for treatment of patients with cerebrovascular disease.

A large-sample assessment of possible association between ischaemic stroke and rs12188950 in the PDE4D gene

Previous reports have shown ambiguous findings regarding the possible associations between ischaemic stroke (IS) and single nucleotide polymorphisms (SNPs) in the phosphodiesterase 4D (PDE4D) gene region. The SNP rs12188950 (or SNP45) has often been studied in this context. We performed a multi-centre study involving a large sample of 2599 IS patients and 2093 control subjects from the south and west regions of Sweden to replicate previous studies regarding IS risk and rs12188950. Subjects from Lund Stroke Register (LSR), Malmö Diet and Cancer Study (MDC) and Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS) were enroled. Subgroups of participants with hypertension and participants <55 years of age, as well as the TOAST subgroups large vessel disease, small vessel disease and cardioembolism, were also assessed. Univariate odds ratios (ORs) and ORs controlling for hypertension, diabetes and current smoking were calculated. We additionally performed a meta-analysis including 10,500 patients and 10,102 control subjects from 17 publications (including the present study). When assessing pooled data from LSR, MDC and SAHLSIS we obtained no association between IS and rs12188950 for all participants (OR=0.93; 95% confidence interval (CI): 0.83-1.05). Significant associations were not found for hypertensive participants or participants with age <55, or when separately evaluating patients from the three different TOAST subgroups. The meta-analysis showed no significant overall estimate (OR=0.96; 95% CI: 0.89-1.04) with significant heterogeneity for random effect (P=0.042). No effect from rs12188950 on IS was found from either our pooled multi-centre data or the performed meta-analysis. We did not find any association between the examined subgroups and rs12188950 either.

Association of the phosphodiesterase 4D (PDE4D) gene and cardioembolic stroke in an Australian cohort

BACKGROUND

Large-scale epidemiological studies support an important role for susceptibility genes in the pathogenesis of ischemic stroke, with phosphodiesterase 4D identified as the first gene predisposing to ischemic stroke. Several single nucleotide polymorphisms within the phosphodiesterase 4D gene have been implicated in the pathogenesis of stroke. Aim Undertake a multivariate analysis of six single nucleotide polymorphisms within the phosphodiesterase 4D gene in a previously defined Australian stroke cohort, to determine whether these single nucleotide polymorphisms have an association with ischemic stroke.

METHODS

This case-control study was performed using an existing genetic database of 180 ischemic stroke patients and 301 community controls, evaluated previously for cerebrovascular risk factors (hypertension, hypercholesterolemia, diabetes, paroxysmal atrial fibrillation, smoking and history of stroke in a first-degree relative). Based on previously reported associations with large vessel disease, ischemic stroke, cardioembolic stroke or a mixture of these, six single nucleotide polymorphisms in the phosphodiesterase 4D gene were selected for study, these being single nucleotide polymorphisms 13, 19, rs152312, 45, 83 and 87, based on previously utilized DeCODE nomenclature. Single nucleotide polymorphisms were genotyped using a sequence-specific polymerase chain reaction method and gel electrophoresis. Logistic regression was undertaken to determine the relevance of each polymorphism to stroke. Further analysis was undertaken to determine the risk of stroke following stratification for stroke sub-type and etiology.

RESULTS

Significant odds ratios were found to be associated with cardioembolic strokes in two single nucleotide polymorphisms: rs152312 and SNP 45 (P < 0 · 05).

CONCLUSIONS

Our findings demonstrated an association between cardioembolic stroke and phosphodiesterase 4D single nucleotide polymorphisms rs152312 and 45. No significant association was found for the other four single nucleotide polymorphisms investigated within the phosphodiesterase 4D gene. We propose that the results from this Australian population support the concept that a large prospective international study is required to investigate the role of phosphodiesterase 4D in the cardiogenic cause of ischemic stroke.

Meta-analysis of homogeneous subgroups reveals association between PDE4D gene variants and ischemic stroke

BACKGROUND

An Icelandic study showed a significant positive association between phosphodiesterase 4D (PDE4D) gene variants and stroke. However, subsequent studies reported conflicting results, possibly due to small sample sizes and the heterogeneity of the studies.

METHOD

We performed a meta-analysis on 6 SNPs of the PDE4D gene to investigate the association between this gene and ischemic stroke by integrating the results of previous studies, comprising 11,834 cases and 15,233 controls. A pooled genotypic odds ratio (OR) for each SNP was determined under 3 genetic models (i.e. dominant, recessive, and codominant) using both fixed- and random-effects models with consideration for heterogeneity and publication bias across studies.

RESULTS

Among the SNPs included in this study, SNP56 (rs702553) showed the most significant association with ischemic stroke in a meta-analysis comprised of 7 homogenous studies. The overall OR of the TT genotype compared to the AA genotype was 1.29 (95% CI 1.03-1.61; p = 0.022). For SNP83 (rs966221), a protective effect of the ancestral allele T was observed only in Asian populations (ORTT 0.79, 95% CI 0.69-0.90; p = 0.0005). This meta-analysis revealed a significant association of PDE4D gene variants with the risk of ischemic stroke, and further investigations are warranted to evaluate possible ethnic-specific effects.

Lentiviral-Mediated shRNA Silencing of PDE4D Gene Inhibits Platelet-Derived Growth Factor-Induced Proliferation and Migration of Rat Aortic Smooth Muscle Cells

Phosphodiesterase 4D (PDE4D) is a member of the large superfamily of phosphodiesterases. PDE4D polymorphisms have been found to associate with ischemic stroke. Proliferation and migration of vascular smooth muscle cells (VSMCs) play a critical role in the pathogenesis of atherosclerosis. In this study, infection of VSMCs with lentivrius particles carrying shRNA direct against PDE4D significantly inhibited platelet-derived growth factor-induced VSMC proliferation and migration, and the inhibitory effects were not associated with global intracellular cAMP level. Our results implicate that PDE4D has an important role in VSMC proliferation and migration which may explain its genetic susceptibility to ischemic stroke.

Genetics of stroke

Stroke is the second most common cause of death and the most common cause of disability in developed countries. Stroke is a multi-factorial disease caused by a combination of environmental and genetic factors. Numerous epidemiologic studies have documented a significant genetic component in the occurrence of strokes. Genes encoding products involved in lipid metabolism, thrombosis, and inflammation are believed to be potential genetic factors for stroke. Although a large group of candidate genes have been studied, most of the epidemiological results are conflicting. Studies of stroke as a monogenic disease have made huge progress, and animal models serve as an indispensable tool to dissect the complex genetics of stroke. In the present review, we provide insight into the role of in vivo stroke models for the study of stroke genetics.

Sex-differential genetic effect of phosphodiesterase 4D (PDE4D) on carotid atherosclerosis

BACKGROUND

The phosphodiesterase 4D (PDE4D) gene was reported as a susceptibility gene to stroke. The genetic effect might be attributed to its role in modulating the atherogenic process in the carotid arteries. Using carotid intima-media thickness (IMT) and plaque index as phenotypes, the present study sought to determine the influence of this gene on subclinical atherosclerosis.

METHODS

Carotid ultrasonography was performed on 1013 stroke-free subjects who participated in the health screening programs (age 52.6 +/- 12.2; 47.6% men). Genotype distribution was compared among the high-risk (plaque index > or = 4), low-risk (index = 1-3), and reference (index = 0) groups. We analyzed continuous IMT data and further dichotomized IMT data using mean plus one standard deviation as the cutoff level. Because the plaque prevalence and IMT values displayed a notable difference between men and women, we carried out sex-specific analyses in addition to analyzing the overall data. Rs702553 at the PDE4D gene was selected because it conferred a risk for young stroke in our previous report. Previous young stroke data (190 cases and 211 controls) with an additional 532 control subjects without ultrasonic data were shown as a cross-validation for the genetic effect.

RESULTS

In the overall analyses, the rare homozygote of rs702553 led to an OR of 3.1 (p = 0.034) for a plaque index > or = 4. When subjects were stratified by sex, the genetic effect was only evident in men but not in women. Comparing male subjects with plaque index > or = 4 and those with plaque index = 0, the TT genotype was over-represented (27.6% vs. 13.4%, p = 0.008). For dichotomized IMT data in men, the TT genotype had an OR of 2.1 (p = 0.032) for a thicker IMT at the common carotid artery compared with the (AA + AT) genotypes. In women, neither IMT nor plaque index was associated with rs702553. Similarly, SNP rs702553 was only significant in young stroke men (OR = 1.8, p = 0.025) but not in women (p = 0.27).

CONCLUSIONS

The present study demonstrates a sex-differential effect of PDE4D on IMT, plaque index and stroke, which highlights its influence on various aspects of atherogenesis.

The genetics of ischaemic stroke

In this review, we discuss the genetic factors in both the aetiology and treatment of ischaemic stroke. We discuss candidate gene association studies, family linkage studies and the more recent whole genome association studies and whole genome expression studies. We also briefly discuss genetic testing for stroke risk and genetic analysis of treatment complications.

Variants of the arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene and risk of stroke: a HuGE gene-disease association review and meta-analysis

Variants of the arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene have been implicated as a risk factor for stroke. However, genetic association studies that have examined the association between ALOX5AP gene variants (HapA haplotype, HapB haplotype, and SG polymorphisms) and stroke have produced conflicting results. Therefore, the authors performed a meta-analysis of all studies with ALOX5AP genotyping (5,194 stroke cases and 4,566 controls). The meta-analysis showed significant heterogeneity among studies (P(Q) = 0.03, I(2) = 63%) and a nonsignificant association between the HapA haplotype (SG13S25G-SG13S114T-SG13S89G-SG13S32A) and stroke risk (random-effects (RE) odds ratio (OR) = 1.13, 95% confidence interval (CI): 0.88, 1.45). Regarding the HapB haplotype (SG13S377A-SG13S114A-SG13S41A-SG13S35G), there was no association with stroke risk (RE OR = 1.03, 95% CI: 0.77, 1.37). The SG13S114, SG13S89, SG13S25, SG13S32, SG13S35, and SG13S42 polymorphisms were not associated with stroke. The SG13S106 and SG13S377 polymorphisms revealed evidence of marginal association (RE OR = 1.23 (95% CI: 1.03, 1.46) and RE OR = 1.25 (95% CI: 1.04, 1.50), respectively). However, cumulative meta-analysis for the HapA haplotype showed a downward trend of odds ratios over time, and recursive cumulative meta-analysis indicated insufficient evidence for claiming or denying an association. Tests for bias revealed no evidence of biases. Rigorous genetic association studies investigating gene-gene-environment interactions may generate more conclusive claims about the genetics of stroke.

Lack of association between variations of PDE4D and ischemic stroke in the Japanese population

BACKGROUND AND PURPOSE

After the first genomewide association study of ischemic stroke identified PDE4D as a susceptible gene, many replication studies have been conducted. However, the validity of the association has remained controversial because of the heterogeneity of both genetic markers and phenotypes.

METHODS

We investigated the association between variations of PDE4D and ischemic stroke by 3 methods: single-marker, haplotype, and tag-single nucleotide polymorphism (SNP) analyses. In the single-marker analysis, we evaluated the association using 2 large case-control samples (1112 cases and 1112 control subjects in a sample obtained from Kyushu, Japan, and 1711 cases and 1786 control subjects in BioBank Japan) and a prospective cohort with 14 years of follow-up. These samples were analyzed both separately and pooled. Haplotype and tag-SNP analyses were performed using the 2 case-control samples together.

RESULTS

In single-marker association tests, we found no significant association in the same direction among the 6 SNP reported in the initial study and ischemic stroke subtypes. Haplotype analysis revealed no significant association between the region around the 5'-end of the gene and combined atherothrombotic and cardioembolic infarction. Rs7730070, a SNP located around the 3'-end of PDE4D, showed the lowest nominal probability value by tag-SNP analysis but was not significant after adjustment for multiple testing (adjusted probability value =0.36).

CONCLUSIONS

These results suggest that variations in PDE4D are not associated with ischemic stroke risk in the Japanese population.

Genetic profile of ischemic cerebrovascular disease and carotid stenosis

OBJECTIVES

Carotid artery stenosis (CS) is a major risk factor for ischemic cerebrovascular disease (ICVD) and is therefore of interest in genetic investigating. Here we report the distribution of 100 polymorphisms in 47 suspected susceptibility genes for ICVD and its risk factors.

MATERIALS AND METHODS

Previously published markers in suspected susceptibility genes were genotyped in ICVD patients and controls (928/602). Genotyping was performed using multiplex polymerase chain reaction (PCR) and linear immobilized probe array assays. ICVD cases were subtyped according to Trial of Org 10172 in Acute Stroke Treatment (TOAST) or subdivided into CS and non-CS patients by ultrasonography in a separate analysis.

RESULTS

Three polymorphisms located in the lipoprotein lipase (LPL), angiotensinogen (AGT) and guanine nucleotide-binding protein beta-3 (GNB3) genes were significantly associated with ICVD after correction for age and gender. The strongest association was found for the protective LPL Ser447Term polymorphism. All the significant markers showed varying frequencies in different subphenotypes of ICVD. Factor VII, apolipoprotein E and two renin polymorphisms were differentially frequent in patients with evidence of CS compared with non-CS patients.

CONCLUSIONS

We have found that some previously described susceptibility polymorphisms are weakly associated with ICVD and that subdivision of patients into CS and non-CS groups may help to identify new candidate polymorphisms.

Variation in the PDE4D gene and ischemic stroke risk: a systematic review and meta-analysis on 5200 cases and 6600 controls

BACKGROUND AND PURPOSE

PDE4D was identified as the first novel gene associated with ischemic stroke risk. Replication studies have produced conflicting results, but many have been small and underpowered. Meta-analysis provides a method to combine this data and determine in a larger sample size whether the association with PDE4D can be replicated.

METHODS

A meta-analysis of all PDE4D variants investigated in relation to ischemic stroke has been undertaken. Analysis of any variant appearing in 2 or more replication studies was included; this comprised 6 single nucleotide polymorphisms together with allele 0 of minisatellite AC008818 and the G0 haplotype. A total of 16 studies were identified, allowing examination of up to 5216 cases and 6615 controls for a single variant. Analyses were performed including all data, excluding data from the original report (providing true replication data), and for individual stroke subtypes and limited to white ethnicity.

RESULTS

No individual single nucleotide polymorphism was associated with all ischemic stroke cases. Allele 0 of AC008818 and haplotype G0 carriers was associated with increased risk (relative risk, 1.12; 95 CI, 1.01 to 1.25; P=0.03 and relative risk, 1.18; 95% CI, 1.05 to 1.33; P=0.007), but these associations became nonsignificant after exclusion of the original study from the analysis (relative risk, 1.06; 95% CI, 0.94 to 1.20; P=0.34 and relative risk, 1.16; 95% CI, 1.00 to 1.34; P=0.06, respectively). Analyzing only whites, the majority of cases studied, did not result in a significant association for any analysis. Few robust associations were found with individual stroke subtypes.

CONCLUSIONS

No genetic variant examined in PDE4D showed a robust and reproducible association to ischemic stroke. Any association that may exist is likely to be weak and potentially restricted to specific populations.