Hereditary risk factors for stroke in humans - Association studies with emphasis on familial and genotypic factors

Background Stroke is a serious vascular disorder that comprises intracerebral hemorrhages, subarachnoid hemorrhages and ischemic stroke (IS). The etiology of stroke, including hereditary components induced by cellular mechanisms, is therefore a research field of vital importance. The aim of this thesis was to assess possible genetic impact on stroke risk. We thus evaluated family history of stroke-related individual traits as well as allelic variations in selected candidate genes. Methods Association studies, primarily of Lund Stroke Register data, were fundamentals in the analyses in order to find possible genetic association with stroke risk. Hereditary risk factors, based on family-history data and candidate gene studies, were considered. Statistical methods for assessing the data, including basic chi-square tests of two-by-two tables as well as various logistic regression approaches and meta-analysis applications using the DerSimonian-Laird method, were used. TOAST subtypes of ischemic stroke were considered when available. Also, 25 coronary artery disease (CAD) susceptible SNPs from various genetic loci were joined together in risk scores and tested against IS risk by logistic regression. Results Paper I: The prevalence of stroke or TIA among first-degree relatives may affect the proband’s stroke risk (odds ratio, OR=1.74; 95% confidence interval, CI: 1.36-2.22), especially when considering mothers and offsprings (OR=2.04; 95% CI: 1.30-3.20). No such association was seen at all between spouses. Papers II-III: SNP rs12188950 was significantly associated with IS in Paper II (OR=0.72; 95% CI: 0.58-0.91; N=1324), but not in Paper III (OR=0.93; 95% CI: 0.83-1.05; N=4692) where a different sample representing an analogous Swedish population was used. Paper IV: SNP rs4977574 on chromosome 9p21 was related to IS risk (OR=1.12; 95% CI: 1.04-1.20) and large vessel disease risk (OR=1.36; 95% CI: 1.13-1.64). This genetic effect of chromosome 9p21 on IS was however already known. None of the other 24 SNPs or compiled risk scores were significant. Conclusions and discussion Significant transmission of stroke from parents to offsprings but not between spouses suggests a genetic inheritance component. But, for SNPs representing some particular carefully selected genes, the findings regarding possible impact on IS were not that clear: Ambiguous results were obtained, many significance tests were also negative. Moreover, we could not generally find significant associations between SNPs susceptible for CAD and IS risk

Variations in apolipoprotein D and sigma non-opioid intracellular receptor 1 genes with relation to risk, severity and outcome of ischemic stroke

Background: In experimental studies, the apolipoprotein D (APOD) and the sigma receptor type 1 (SIGMAR1) have been related to processes of brain damage, repair and plasticity. Methods: We examined blood samples from 3081 ischemic stroke (IS) patients and 1595 control subjects regarding 10 single nucleotide polymorphisms (SNPs) in the APOD (chromosomal location 3q29) and SIGMAR1 (chromosomal location 9p13) genes to find possible associations with IS risk, IS severity (NIHSS-score) and recovery after IS (modified Rankin Scale, mRS, at 90 days). Simple/multiple logistic regression and Spearman's rho were utilized for the analyses. Results: Among the SNPs analyzed, rs7659 within the APOD gene showed a possible association with stroke risk (OR = 1.12; 95% CI: 1.01-1.25; P = 0.029) and stroke severity (NIHSS >= 16) (OR = 0.70; 95% CI: 0.54-0.92; P = 0.009) when controlling for age, sex and vascular risk factors for stroke. No SNP showed an association with stroke recovery (mRS). Conclusions: We conclude that the SNP rs7659 within the APOD gene might be related to risk and severity of ischemic stroke in patients

A Common Missense Variant in the ATP Receptor P2X7 Is Associated with Reduced Risk of Cardiovascular Events

BACKGROUND AND PURPOSE: Extracellular adenosine triphosphate (ATP) regulates inflammatory cells by activation of the P2X(7) receptor. We hypothesized that polymorphisms in P2RX7 influence the risk of ischemic heart disease (IHD), ischemic stroke (IS) and cardiovascular risk factors and tested this hypothesis using genetic association studies. METHODS: Two loss-of-function SNPs in P2RX7 were genotyped in 1244 IHD cases and 2488 controls as well as 5969 individuals with cardiovascular risk factors. Eleven SNPs in a 250 kb region on chromosome 12 spanning P2RX7 as well as neighboring genes OASL, P2RX4 and CAMKK2 were genotyped in 4138 individuals with IS and 2528 controls. Association was examined using linear and logistic regression models with an additive genetic model. RESULTS: The common loss-of-function variant rs3751143 was significantly associated with a decreased risk of IHD in smokers (P = 0.03) as well as decreased risk of IS (OR 0.89; 95% CI = 0.81-0.97; P = 0.012). In addition, an intronic SNP in CAMKK2, rs2686342, were associated with a decreased risk of IS (OR 0.89; 95% CI = 0.82-0.97; P = 0.011). In subgroup analyses, both SNPs were associated with decreased risk of IS in individuals with hypertension (P = 0.045 and 0.015, respectively). CONCLUSIONS: A common loss-of-function missense variant in the gene encoding the P2X(7) receptor is associated with reduced risk of IS and with IHD in smokers. These findings might implicate a role of purinergic signaling in atherogenesis or atherothrombosis

Multiplicity of Risk Factors in Ischemic Stroke Patients: Relations to Age, Sex, and Subtype - A Study of 2,505 Patients from the Lund Stroke Register.

Background: The prevalence of risk factors for ischemic stroke may vary between different groups of stroke patients. We examined the distribution of individual well-established risk factors as well as the multiplicity of risk factors in different age groups and among subtypes. Methods: In the Lund Stroke Register, we consecutively enrolled 2,505 patients with first-ever ischemic stroke from 2001 to 2009 and registered hypertension, diabetes mellitus, heart disease, current smoking, hypercholesterolemia as well as stroke subtype. Results: Among young patients (<55 years), at least 50% had ≥2 risk factors and 20-25% had ≥3 risk factors. In patients aged 55 years or older, the proportion with ≥2 risk factors was 70-80% and with ≥3 risk factors 35-45%. Men and women had a similar burden of risk factors. Approximately 50% of the cases classified as cardioembolism (CE) and large artery atherosclerosis (LAA) had ≥3 risk factors, which was significantly more than the other TOAST (Trial of Org 10172 in Acute Stroke Treatment) subtypes (CE p < 0.001, LAA p = 0.001). Conclusions: The prevalence of well-established risk factors is similar among young and old stroke patients with large proportions (50-80%) having ≥2 risk factors. Even though the prevalence of well-established risk factors differs between pathogenetic subtypes, these risk factors as well as the multiplicity of risk factors seem to be of clinical importance in all major subtypes of ischemic stroke. © 2014 S. Karger AG, Basel

Sonographic visualization of the rectoanal inhibitory reflex in children suspected of having hirschsprung disease: a pilot study.

OBJECTIVE: To date, for detection of the absence of peristalsis in children with chronic constipation and a suspicion of Hirschsprung disease (HD), children have been investigated with a contrast enema. If the radiographic investigation is inconclusive, anometry and a rectal biopsy are performed. A new noninvasive real-time sonographic method for examination of the rectoanal inhibitory reflex (RAIR) was compared with anometry. METHODS: The rectum and anal canal of children were visualized transperineally on sonography. The RAIR was elicited by injecting water into the rectum, and the events in the bowel were recorded on video for offline analysis. RESULTS: Injection of water initiated a peristaltic wave that moved the rectal contents into the proximal part of the anal canal in healthy children. Among 28 children with suspected HD, 3 showed aganglionosis in their biopsy samples. These 3 children lacked the RAIR according to both sonography and anometry. Both methods had a negative predictive value of 100%. In 17 children, the RAIR was present according to both sonography and anometry, and all of these children had normal histologic findings. In 8 children, sonography did not show the reflex despite normal histologic findings; in 2 of these, the quality of the investigation made the evaluation uncertain. CONCLUSIONS: This pilot study indicates that in children with chronic constipation, a transperineal sonographic examination of the RAIR is comparable to anometry and can facilitate the diagnose of HD

Recruited fibroblasts reconstitute the peri-islet membrane : a longitudinal imaging study of human islet grafting and revascularisation

Aims/hypothesis: Rapid and adequate islet revascularisation and restoration of the islet–extracellular matrix (ECM) interaction are significant factors influencing islet survival and function of the transplanted islets in individuals with type 1 diabetes. Because the ECM encapsulating the islets is degraded during islet isolation, understanding the process of revascularisation and engraftment after transplantation is essential and needs further investigation. Methods: Here we apply a longitudinal and high-resolution imaging approach to investigate the dynamics of the pancreatic islet engraftment process up to 11 months after transplantation. Human and mouse islet grafts were inserted into the anterior chamber of the mouse eye, using a NOD.ROSA-tomato.Rag2−/− or B6.ROSA-tomato host allowing the investigation of the expansion of host vs donor cells and the contribution of host cells to aspects such as promoting the encapsulation and vascularisation of the graft. Results: A fibroblast-like stromal cell population of host origin rapidly migrates to ensheath the transplanted islet and aid in the formation of a basement membrane-like structure. Moreover, we show that the vessel network, while reconstituted by host endothelial cells, still retains the overall architecture of the donor islets. Conclusions/interpretation: In this transplantation situation the fibroblast-like stromal cells appear to take over as main producers of ECM or act as a scaffold for other ECM-producing cells to reconstitute a peri-islet-like basement membrane. This may have implications for our understanding of long-term graft rejection and for the design of novel strategies to interfere with this process

Genetic Variant on Chromosome 12p13 Does Not Show Association to Ischemic Stroke in 3 Swedish Case-Control Studies

Background and Purpose-In a genome-wide association study and subsequent case-control studies, the single-nucleotide polymorphism rs12425791 on chromosome 12p13 was reported to be associated with ischemic stroke, but this could not be validated in a recent well-powered study. We therefore investigated whether an association between ischemic stroke and rs12425791 could be detected in 3 different case-control studies from the southwest of Sweden. Methods-We examined 3606 patients with ischemic stroke and 2528 controls from 3 independent case-controls studies. Results-No significant association between ischemic stroke and the single-nucleotide polymorphism rs12425791 was detected in any of the 3 case-control samples or in the samples combined. The odds ratio for ischemic stroke for the minor allele in the combined sample was 1.02 (95% CI, 0.93 to 1.13). Conclusions-The single-nucleotide polymorphism rs12425791 does not confer a substantial risk for ischemic stroke in our population. Our results support a recent large study including other European populations. (Stroke. 2011;42:214-216.