Stroke genetics: a review and update

Inflammation and endothelial function relevant genetic polymorphisms, carotid atherosclerosis, and vascular events in high-risk stroke population

Aim

To identify the associations of 19 single nucleotide polymorphisms (SNPs) in genes involved in inflammation and endothelial function and carotid atherosclerosis with subsequent ischemic stroke and other vascular events in the high-risk stroke population.

Methods

This was a multicenter community-based sectional survey and prospective cohort study in Sichuan, southwestern China. Eight communities were randomly selected, and the residents in each community were surveyed using a structured face-to-face questionnaire. Carotid ultrasonography and DNA information were obtained from 2,377 out of 2,893 individuals belonging to a high-risk stroke population. Genotypes of the 19 SNPs in genes involved in inflammation and endothelial function were measured. All the 2,377 subjects were followed up for 4.7 years after the face-to-face survey. The primary outcome was ischemic stroke, and the secondary outcome was a composite of vascular events.

Results

Among the 2,377 subjects, 2,205 (92.8%) completed a 4.7-year follow-up, 947 (42.9%) had carotid atherosclerosis [372 (16.9%) carotid vulnerable plaque, 405 (18.4%) mean IMT > 0.9 mm, 285 (12.0%) carotid stenosis ≥15%]. Outcomes occurred in 158 (7.2%) subjects [92 (4.2%) ischemic stroke, 17 (0.8%) hemorrhagic stroke, 48 (2.2%) myocardial infarction, and 26 (1.2%) death] during follow-up. There was a significant gene-gene interaction among ITGA2 rs1991013, IL1A rs1609682, and HABP2 rs7923349 in the 19 SNPs. The multivariate logistic regression model revealed that carotid atherosclerosis and the high-risk interactive genotypes among the three SNPs were independent with a higher risk for ischemic stroke (OR = 2.67, 95% CI: 1.52-6.78, p = 0.004; and OR = 3.11, 95% CI: 2.12-9.27, p < 0.001, respectively) and composite vascular events (OR = 3.04, 95% CI: 1.46-6.35, p < 0.001; and OR = 3.23, 95% CI: 1.97-8.52, p < 0.001, respectively).

Conclusion

The prevalence of carotid atherosclerosis was shown to be very high in the high-risk stroke population. Specific SNPs, interactions among them, and carotid atherosclerosis were independently associated with a higher risk of ischemic stroke and other vascular events.

Genetic and Environmental Factors and Cardiovascular Disease Risk in Adolescents

Importance

Cardiovascular risk factors in youth have been associated with future cardiovascular disease (CVD), but conventional observational studies are vulnerable to genetic and environmental confounding.

Objective

To examine the role of genetic and environmental factors shared by full siblings in the association of adolescent cardiovascular risk factors with future CVD.

Design, Setting, and Participants

This is a nationwide cohort study with full sibling comparisons. All men who underwent mandatory military conscription examinations in Sweden between 1972 and 1995 were followed up until December 31, 2016. Data analysis was performed from May 1 to November 10, 2022.

Exposures

Body mass index (BMI), cardiorespiratory fitness, blood pressure, handgrip strength, and a combined risk z score in late adolescence.

Main Outcomes and Measures

The primary outcome was fatal or nonfatal CVD, as recorded in the National Inpatient Register or the Cause of Death Register before 2017.

Results

A total of 1 138 833 men (mean [SD] age, 18.3 [0.8] years), of whom 463 995 were full brothers, were followed up for a median (IQR) of 32.1 (26.7-37.7) years, during which 48 606 experienced a CVD outcome (18 598 among full brothers). All risk factors were associated with CVD, but the effect of controlling for unobserved genetic and environmental factors shared by full siblings varied. In the sibling analysis, hazard ratios for CVD (top vs bottom decile) were 2.10 (95% CI, 1.90-2.32) for BMI, 0.77 (95% CI, 0.68-0.88) for cardiorespiratory fitness, 1.45 (95% CI, 1.32-1.60) for systolic blood pressure, 0.90 (95% CI, 0.82-0.99) for handgrip strength, and 2.19 (95% CI, 1.96-2.46) for the combined z score. The percentage attenuation in these hazard ratios in the sibling vs total cohort analysis ranged from 1.1% for handgrip strength to 40.0% for cardiorespiratory fitness. Consequently, in the sibling analysis, the difference in cumulative CVD incidence at age 60 years (top vs bottom decile) was 7.2% (95% CI, 5.9%-8.6%) for BMI and 1.8% (95% CI, 1.0%-2.5%) for cardiorespiratory fitness. Similarly, in the sibling analysis, hypothetically shifting everyone in the worst deciles of BMI to the middle decile would prevent 14.9% of CVD at age 60 years, whereas the corresponding number for cardiorespiratory fitness was 5.3%.

Conclusions and Relevance

In this Swedish national cohort study, cardiovascular risk factors in late adolescence, especially a high BMI, were important targets for CVD prevention, independently of unobserved genetic and environmental factors shared by full siblings. However, the role of adolescent cardiorespiratory fitness in CVD may have been overstated by conventional observational studies.

X, but not Y, Chromosomal Complement Contributes to Stroke Sensitivity in Aged Animals

Post-menopausal women become vulnerable to stroke and have poorer outcomes and higher mortality than age-matched men, and previous studies suggested that sex chromosomes play a vital role in mediating stroke sensitivity in the aged. It is unknown if this is due to effects of the X or Y chromosome. The present study used the XY* mouse model (with four genotypes: XX and XO gonadal females and XY and XXY gonadal males) to compare the effect of the X vs. Y chromosome compliment in stroke. Aged (18-20 months) and gonadectomized young (8-12 weeks) mice were subjected to a 60-min middle cerebral artery occlusion. Infarct volume and behavioral deficits were quantified 3 days after stroke. Microglial activation and infiltration of peripheral leukocytes in the aged ischemic brain were assessed by flow cytometry. Plasma inflammatory cytokine levels by ELISA, and brain expression of two X chromosome-linked genes, KDM6A and KDM5C by immunochemistry, were also examined. Both aged and young XX and XXY mice had worse stroke outcomes compared to XO and XY mice, respectively; however, the difference between XX vs. XXY and XO vs. XY aged mice was minimal. Mice with two copies of the X chromosome showed more robust microglial activation, higher brain-infiltrating leukocytes, elevated plasma cytokine levels, and enhanced co-localization of KDM6A and KDM5C with Iba1+ cells after stroke than mice with one X chromosome. The number of X chromosomes mediates stroke sensitivity in aged mice, which might be processed through the X chromosome-linked genes and the inflammatory responses.

Endovascular thrombectomy for acute ischemic stroke

This review describes the evolution of endovascular treatment for acute ischemic stroke, current state of the art, and the challenges for the next decade. The rapid development of endovascular thrombectomy (EVT), from the first attempts into standard of care on a global scale, is one of the major achievements in modern medicine. It was possible thanks to the establishment of a scientific framework for patient selection, assessment of stroke severity and outcome, technical development by dedicated physicians and the MedTech industry, including noninvasive imaging for patient selection, and radiological outcome evaluation. A series of randomized controlled trials on EVT in addition to intravenous thrombolytics, with overwhelmingly positive results for anterior circulation stroke within 6 h of onset regardless of patient characteristics with a number needed to treat of less than 3 for any positive shift in outcome, paved the way for a rapid introduction of EVT into clinical practice. Within the "extended" time window of 6-24 h, the effect has been even greater for patients with salvageable brain tissue according to perfusion imaging with a number needed to treat below 2. Even so, EVT is only available for a small portion of stroke patients, and successfully recanalized EVT patients do not always achieve excellent functional outcome. The major challenges in the years to come include rapid prehospital detection of stroke symptoms, adequate clinical and radiological diagnosis of severe ischemic stroke cases, enabling effective recanalization by EVT in dedicated angiosuites, followed by personalized post-EVT stroke care.

Genetics in aphasia recovery

Considerable research efforts have been exerted toward understanding the mechanisms underlying recovery in aphasia. However, predictive models of spontaneous and treatment-induced recovery remain imprecise. Some of the hitherto unexplained variability in recovery may be accounted for with genetic data. A few studies have examined the effects of the BDNF val66met polymorphism on aphasia recovery, yielding mixed results. Advances in the study of stroke genetics and genetics of stroke recovery, including identification of several susceptibility genes through candidate-gene or genome-wide association studies, may have implications for the recovery of language function. The current chapter discusses both the direct and indirect evidence for a genetic basis of aphasia recovery, the implications of recent findings within the field, and potential future directions to advance understanding of the genetics-recovery associations.

Blood-Brain Barrier Mechanisms in Stroke and Trauma

The brain microenvironment is tightly regulated. The blood-brain barrier (BBB), which is composed of cerebral endothelial cells, astrocytes, and pericytes, plays an important role in maintaining the brain homeostasis by regulating the transport of both beneficial and detrimental substances between circulating blood and brain parenchyma. After brain injury and disease, BBB tightness becomes dysregulated, thus leading to inflammation and secondary brain damage. In this chapter, we overview the fundamental mechanisms of BBB damage and repair after stroke and traumatic brain injury (TBI). Understanding these mechanisms may lead to therapeutic opportunities for brain injury.

Does exercise prevent major non-communicable diseases and premature mortality? A critical review based on results from randomized controlled trials

Observational studies show that physical activity is strongly associated with a reduced risk of premature mortality and major non-communicable diseases. We reviewed to which extent these associations have been confirmed in randomized controlled trials (RCTs) for the outcomes of mortality, cardiovascular disease (CVD), type 2 diabetes (T2D), and fracture. The results show that exercise does not reduce all-cause mortality and incident CVD in older adults or in people with chronic conditions, based on RCTs comprising ∼50,000 participants. The results also indicate a lack of effect on cardiovascular mortality in people with chronic conditions, based on RCTs comprising ∼11,000 participants. Furthermore, there is inconsistent evidence regarding the effect of exercise on fractures in older adults, based on RCTs comprising ∼40,000 participants. Finally, based on RCTs comprising ∼17,000 participants, exercise reduces T2D incidence in people with prediabetes when combined with dietary modification, although evidence for the individual effect of exercise is lacking. Identified shortcomings of the current evidence include risks of publication bias, lack of high-quality studies in certain high-risk populations, and inconstant evidence with respect to some outcomes. Thus, additional large trials would be of value, especially with fracture as the primary outcome. In conclusion, according to current RCT evidence, exercise can prevent T2D assuming it is combined with dietary intervention. However, the current evidence shows that exercise does not prevent premature mortality or CVD, with inconsistent evidence for fractures.

Pure Thalamic Infarct: 8-Year Follow-Up Study in a Hospital in China

Pure thalamic infarct is a rare lacunar stroke type, with little known about long-term outcomes. This 8-year, single-center, retrospective study evaluated the clinical background, etiology, Trial of ORG 10172 in Acute Stroke Treatment (TOAST) classification, and 8-year follow-up results in 27 patients with pure thalamic infarcts identified by MR diffusion-weighted imaging in Dalian, China. All patients presented chief complaints of limb weakness or sensory disturbances. Hypertension (24/27, 88.9%), diabetes (12/27, 44.4%), atrial fibrillation (1/27, 3.7%), hyperlipidemia (10/27, 37%), hyperhomocysteinemia (6/27, 22.2%), smoking history (10/27, 37%; 9/15, 60% for men; 1/12, 8.3% for women), and excessive alcohol consumption history (7/27, 25.9%; 7/15, 46.7% for men; 0 for women) were observed in our patient population. Based on TOAST classification, 1 patient had large artery atherosclerosis (7.14%), 23 had small vessel occlusion (SVO; 85.2%), and 3 patients were unidentified due to lack of cerebral angiography. The thalamic blood supply classification were as follows: 23 (85.2%), inferolateral territory; 1 (3.7%), tuberothalamic territory; 2 (7.4%), combination of tuberothalamic and paramedian arteries; 1 (3.7%), combination of inferolateral and paramedian arteries; 0, posterior choroidal arteries. During the 8-year follow-up, 3 patients died of colon cancer, multi-organ failure, and kidney failure, respectively; 7 presented with a recurrent stroke; while 10 recovered well with their risk factors under control. In conclusion, our cohort of pure thalamic infarcts were mainly due to SVO (TOAST), with hypertension as the main risk factor, and the inferolateral artery as the most implicated arterial territory. Less severe outcome or stroke recurrence are identified in long-term follow-up of pure thalamic infarcts. Other comorbidities would be cause of death in aged patients.

Interactive Association Between CYP2C9 rs2860905 Polymorphism and Atrial Fibrillation on Ischemic Stroke in Taiwan Biobank Participants

Purpose

Ischemic stroke accounts for approximately 85% of all strokes. Risk factors include atrial fibrillation, metabolic disorders, and genetic and lifestyle factors. There is limited evidence to support the association between atrial fibrillation and the risk of ischemic stroke based on genetic variants. We assessed the relationship between ischemic stroke and atrial fibrillation among participants in Taiwan Biobank (TWB) based on the rs2860905 variant of the cytochrome P450 Family 2 Subfamily C Member 9 (CYP2C9) gene.

Materials and Methods

Using logistic regression analysis, we estimated the odds ratios (OR) and 95% confidence intervals (CI) for ischemic stroke among 17,726 biobank adults recruited from 2008 through 2015.

Results

Of the eligible participants (n = 17,726), 906 were identified with ischemic stroke. Atrial fibrillation was positively associated with ischemic stroke (OR=3.70; 95% CI, 2.21–6.20), whereas the rs2860905 variant was not. The OR for ischemic stroke among those with GA/AA genotype was 1.00 (95% CI, 0.82–1.22) compared to those with the GG genotype. Based on the genotype-stratified analysis, the OR for ischemic stroke was 4.68 (95% CI, 2.70–8.09) among individuals with GG genotype who had atrial fibrillation compared to those who did not.

Conclusion

These results demonstrate that the GG genotype of the CYP2C9 rs2860905 variant appears to enhance the risk of ischemic stroke among adults in Taiwan. It could be essential to factor this genotype-specific contributor to ischemic stroke into clinical and experimental investigations of the disease in Taiwan.

The protective effects of the methylenetetrahydrofolate reductase rs1801131 variant among Saudi smokers

Methylenetetrahydrofolate reductase (MTHFR) polymorphism plays a fundamental role in susceptibility to various diseases, including cancers and autoimmune diseases. In the current study, we aimed to compare genotype and allele frequency variations of rs1801131, one of the most common variants found in the MTHFR gene, among Saudi smokers and non-smokers. We hypothesized that genetic variations of this gene are responsible for many diseases, particularly those caused by cigarette smoking (CS) such as pulmonary diseases, oral cancer and lung cancer. We performed a case-control study on a sample of 235 healthy smokers and 239 healthy non-smokers in Saudi Arabia. The rs1801131 SNP genotypes were determined using a genotyping assay and multiple in silico algorithmic software programs were used to identify the effects and structural functions of the rs1801131 (Glu429Ala) mutation. Using chi-squared tests, we found that, among smokers, TG and GG genotype carriers had 0.209-fold (OR = 0.209, P < 0.005) and 0.427-fold (OR = 0.427, P = 0.003) lower risks of CS-related disease compared to TT reference genotypes. In addition, this protective effect was observed in Saudi smokers independent of age, gender, types of smoking, duration, and average daily smoking consumption. Filling a research gap by exploring this topic in the Saudi population, the current findings indicate that genotype and allele distributions of MTHFR rs1801131 polymorphism present fundamental protective effects against the risk of CS-related disease. These findings should be verified in future studies with larger sample sizes, different ethnicities, and patients suffering from CS-related diseases, such as oral cancer and lung cancer.

Association Study of SLC6A4 (5-HTTLPR) Polymorphism and Its Promoter Methylation with Rehabilitation Outcome in Patients with Subacute Stroke

Recently it has been suggested that serotonin transporter (SLC6A4) and its 5HTTLPR polymorphism could be involved in post stroke recovery. Here, we characterized the methylation profile of two different CpG islands within the SLC6A4 promoter region in the whole blood of 50 patients with subacute stroke before and after a six-week rehabilitation treatment. These patients were genotyped for 5HTTLPR polymorphism identifying patients on the basis of short (S) and L (L) alleles: 17 patients LL, 22 patients LS and 11 patients SS. At baseline, all CpG sites for both CpG islands displayed a heterogeneous methylation percentage that were not influenced by the different genotypes. After rehabilitation, we found a significant variation in the methylation levels (increase/decrease) in the specific CpG sites of both CpG islands. The statistical analysis showed a significant relationship between the LL, LS and SS alleles and the outcome of the rehabilitation intervention (χ² (2,50) = 6.395, p = 0.041). Specifically, we found a significant difference between patients with or without a favorable outcome in the LL (11.1% with a favorable outcome) and in the SS (54.4% with a favorable outcome) groups. Our data suggest that 5-HTTLPR polymorphisms and SLC6A4 promoter methylation may be employed as a non-invasive biological marker of recovery in patients with stroke undergoing rehabilitation.

Genetic Variants of lncRNA GAS5 Contribute to Susceptibility of Ischemic Stroke among Southern Chinese Population

Emerging evidence suggests that the long noncoding RNA (lncRNA) growth arrest special 5 (GAS5) plays crucial roles in the pathogenesis of ischemic stroke (IS). The current research is aimed at assessing the correlation between two functional GAS5 variants (rs145204276 and rs55829688) and susceptibility to IS in a Han Chinese population. This study genotyped the two GAS5 variants in 1086 IS patients as well as 1045 age-matched healthy controls by using an improved multitemperature ligase detection reaction (iMLDR-TM) genotyping technology. We observed a considerable change in the frequencies of the rs145204276 allele and genotype among the IS patients and healthy control group. The del-T haplotype was substantially more prevalent in the IS cases compared to the control individuals. When study participants were stratified according to environmental factors, we found that the rs145204276 del allele was correlated with a higher risk of IS in male, smokers, hypertensive, and those ≥65 years old. Additional stratification conforming to IS subtypes exhibited that individuals carrying the rs145204276 del allele conferred a higher risk of expanding a larger artery atherosclerosis stroke subset. Moreover, there was a significant association between the rs145204276 del allele and elevated expression of GAS5 in IS patients. In contrast, the frequency of the allele related to rs55829688 was not statistically correlated with IS in all analysis. Our study supports a model wherein the rs145204276 variant in the GAS5 lncRNA is associated with IS risk, thus representing a potentially viable biomarker for IS prevention and treatment.

Identification of circular RNA expression profiles and potential biomarkers for intracerebral hemorrhage

Aim: To investigate the expression profiles of circRNAs after intracerebral hemorrhage (ICH). Materials & methods: RNA sequencing and qRT-PCR were used to investigate and validate circRNA expression levels. Bioinformatics analysis was performed to explore potential functions of the circRNAs. Results: Expression levels of 15 circRNAs were consistently altered in patients with ICH compared with their expression levels in hypertension. Three circRNAs, hsa_circ_0001240, hsa_circ_0001947 and hsa_circ_0001386, individually or combined, were confirmed as promising biomarkers for predicting and diagnosing ICH. The circRNAs were involved mainly in lysine degradation and the immune system. Conclusion: This is the first study to report expression profiles of circRNAs after ICH and to propose that three circRNAs are potential biomarkers for ICH.

MAP3K6 Mutations in a Neurovascular Disease Causing Stroke, Cognitive Impairment, and Tremor

Objective

To describe a possible novel genetic mechanism for cerebral small vessel disease (cSVD) and stroke.

Methods

We studied a Swedish kindred with ischemic stroke and intracerebral hemorrhage, tremor, dysautonomia, and mild cognitive decline. Members were examined clinically, radiologically, and by histopathology. Genetic workup included whole-exome sequencing (WES) and whole-genome sequencing (WGS) and intrafamilial cosegregation analyses.

Results

Fifteen family members were examined clinically. Twelve affected individuals had white matter hyperintensities and 1 or more of (1) stroke episodes, (2) clinically silent lacunar ischemic lesions, and (3) cognitive dysfunction. All affected individuals had tremor and/or atactic gait disturbance. Mild symmetric basal ganglia calcifications were seen in 3 affected members. Postmortem examination of 1 affected member showed pathologic alterations in both small and large arteries the brain. Skin biopsies of 3 affected members showed extracellular amorphous deposits within the subepidermal zone, which may represent degenerated arterioles. WES or WGS did not reveal any potentially disease-causing variants in known genes for cSVDs or idiopathic basal ganglia calcification, but identified 1 heterozygous variant, NM_004672.4 MAP3K6 c.322G>A p.(Asp108Asn), that cosegregated with the disease in this large family. MAP3K6 has known functions in angiogenesis and affects vascular endothelial growth factor expression, which may be implicated in cerebrovascular disease.

Conclusions

Our data strongly suggest the MAP3K6 variant to be causative for this novel disease phenotype, but the absence of functional data and the present lack of additional families with this disease and MAP3K6 mutations still limit the formal evidence for the variant's pathogenicity.

Differentially Expressed Genes and Their Clinical Significance in Ischaemic Stroke: An In-Silico Study

Background

Ischaemic stroke (IS), a multifactorial neurological disorder, is mediated by interplay between genes and the environment and, thus, blood-based IS biomarkers are of significant clinical value. Therefore, this study aimed to find global differentially expressed genes (DEGs) in-silico, to identify key enriched genes via gene set enrichment analysis (GSEA) and to determine the clinical significance of these genes in IS.

Methods

Microarray expression dataset GSE22255 was retrieved from the Gene Expression Omnibus (GEO) database. It includes messenger ribonucleic acid (mRNA) expression data for the peripheral blood mononuclear cells of 20 controls and 20 IS patients. The bioconductor-package ‘affy’ was used to calculate expression and a pairwise t-test was applied to screen DEGs (P < 0.01). Further, GSEA was used to determine the enrichment of DEGs specific to gene ontology (GO) annotations.

Results

GSEA analysis revealed 21 genes to be significantly plausible gene markers, enriched in multiple pathways among all the DEGs (n = 881). Ten gene sets were found to be core enriched in specific GO annotations. JunD, NCX3 and fibroblast growth factor receptor 4 (FGFR4) were under-represented and glycoprotein M6-B (GPM6B) was persistently over-represented.

Conclusion

The identified genes are either associated with the pathophysiology of IS or they affect post-IS neuronal regeneration, thereby influencing clinical outcome. These genes should, therefore, be evaluated for their utility as suitable markers for predicting IS in clinical scenarios.

A Review of Potential Mechanisms of Cryptogenic Stroke and a Recommended Approach to Diagnosis

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BDNF rs6265 Polymorphism and Its Methylation in Patients with Stroke Undergoing Rehabilitation

Brain-Derived Neurotrophic Factor (BDNF) and its rs6265 single nucleotide polymorphism (SNP) play an important role in post-stroke recovery. We investigated the correlation between BDNF rs6265 SNP and recovery outcome, measured by the modified Barthel index, in 49 patients with stroke hospitalized in our rehabilitation center at baseline (T0) and after 30 sessions of rehabilitation treatment (T1); moreover, we analyzed the methylation level of the CpG site created or abolished into BDNF rs6265 SNP. In total, 11 patients (22.4%) were heterozygous GA, and 32 (65.3%) and 6 (12.2%) patients were homozygous GG and AA, respectively. The univariate analysis showed a significant relationship between the BDNF rs6265 SNP and the modified Barthel index cut-off (χ²(1, N = 48) = 3.86, p = 0.049), considering patients divided for carrying (A+) or not carrying (A−) the A allele. A higher percentage of A− patients obtained a favorable outcome, as showed by the logistic regression model corrected by age and time since the stroke onset, compared with the A+ patients (OR: 5.59). At baseline (T0), the percentage of BDNF methylation was significantly different between GG (44.6 ± 1.1%), GA (39.5 ± 2.8%) and AA (28.5 ± 1.7%) alleles (p < 0.001). After rehabilitation (T1), only patients A− showed a significant increase in methylation percentages (mean change = 1.3, CI: 0.4–2.2, p = 0.007). This preliminary study deserves more investigation to confirm if BDNF rs6265 SNP and its methylation could be used as a biological marker of recovery in patients with stroke undergoing rehabilitation treatment.

Alternative Splicing of Putative Stroke/Vascular Risk Factor Genes Expressed in Blood Following Ischemic Stroke Is Sexually Dimorphic and Cause-Specific

Genome-wide association studies have identified putative ischemic stroke risk genes, yet, their expression after stroke is unexplored in spite of growing interest in elucidating their specific role and identifying candidate genes for stroke treatment. Thus, we took an exploratory approach to investigate sexual dimorphism, alternative splicing, and etiology in putative risk gene expression in blood following cardioembolic, atherosclerotic large vessel disease and small vessel disease/lacunar causes of ischemic stroke in each sex compared to controls. Whole transcriptome arrays assessed 71 putative stroke/vascular risk factor genes for blood RNA expression at gene-, exon-, and alternative splicing-levels. Male (n = 122) and female (n = 123) stroke and control volunteers from three university medical centers were matched for race, age, vascular risk factors, and blood draw time since stroke onset. Exclusion criteria included: previous stroke, drug abuse, subarachnoid or intracerebral hemorrhage, hemorrhagic transformation, infection, dialysis, cancer, hematological abnormalities, thrombolytics, anticoagulants or immunosuppressants. Significant differential gene expression (fold change > |1.2|, p < 0.05, partial correlation > |0.4|) and alternative splicing (false discovery rate p < 0.3) were assessed. At gene level, few were differentially expressed: ALDH2, ALOX5AP, F13A1, and IMPA2 (males, all stroke); ITGB3 (females, cardioembolic); ADD1 (males, atherosclerotic); F13A1, IMPA2 (males, lacunar); and WNK1 (females, lacunar). GP1BA and ITGA2B were alternatively spliced in both sexes (all patients vs. controls). Six genes in males, five in females, were alternatively spliced in all stroke compared to controls. Alternative splicing and exon-level analyses associated many genes with specific etiology in either sex. Of 71 genes, 70 had differential exon-level expression in stroke patients compared to control subjects. Among stroke patients, 24 genes represented by differentially expressed exons were male-specific, six were common between sexes, and two were female-specific. In lacunar stroke, expression of 19 differentially expressed exons representing six genes (ADD1, NINJ2, PCSK9, PEMT, SMARCA4, WNK1) decreased in males and increased in females. Results demonstrate alternative splicing and sexually dimorphic expression of most putative risk genes in stroke patients' blood. Since expression was also often cause-specific, sex, and etiology are factors to consider in stroke treatment trials and genetic association studies as society trends toward more personalized medicine.

Ischemic Stroke and Genetic Variants: In Search of Association with Severity and Recurrence in a Brazilian Population

OBJECTIVE

The aim of this study was to investigate the relationship between genetic variants in candidate genes and clinical severity and prognosis (recurrence) of ischemic stroke (IS) in a Brazilian population.

METHODS

This was a retrospective study based on clinical and demographic data retrieved from the JOINVASC cohort-Epidemiological Study on Cerebrovascular Diseases in Joinville and on respective DNA samples available at the Joinville Stroke Biobank, over the period 2010-2015. Four hundred and thirty-five subjects were included. Patients were divided into large artery atherosclerosis (195 cases) and cardioembolic IS (240 cases) subgroups according to Trial of Org 10172 in the Acute Stroke Treatment standards. The severity of the event was established from the score obtained using the National Institutes of Health Stroke Scale. The genotypic and allelic frequencies of each variant were acquired by Real-Time Polymerase Chain Reaction. The codominance model was considered for the analysis of the genotypes' influence.

RESULTS

There was no association between clinical severity and recurrence with variants rs2383207 (CDKN2B-AS1) for atherothrombotic IS and variants rs879324 (ZFHX3), rs966221 (PDE4D), and rs152312 (PDE4D) for cardioembolic IS. The variants rs1396476, rs2910829, rs6843082, and rs2107595 were not in Hardy-Weinberg equilibrium in the evaluated population.

CONCLUSIONS

Although this study failed to identify an association between genetic variants and clinical response variability, the need to carry out related studies with larger number of cases covering other populations and genetic variants remains, which would allow the uncovering of hypothetical genetic factors governing stroke outcomes and recurrence.

Chromosome 10q25 polymorphism is associated with susceptibility to large artery atherosclerotic stroke

BACKGROUND AND AIMS

A recent genome-wide association study (GWAS) reported an association between a single nucleotide polymorphism (SNP) rs11196288 and risk of early-onset large artery atherosclerotic (LAA) stroke in European population. The interaction between genetic and environmental factors such as age has also received increasing attention. We performed this study to investigate the association between the rs11196288A > G polymorphism and LAA stroke risk in the Chinese Han population and test whether age interacts rs11196288 to influence LAA stroke risk.

METHODS

Genotyping of rs11196288 was performed in 1066 LAA stroke patients and 1167 healthy controls. Multivariate logistic regression analyses were applied to assess the effect of the rs11196288A > G polymorphism on susceptibility and short-term outcome of LAA stroke. Nomograms were performed to estimate probability of risk for an individual patient.

RESULTS

A significant decrement of LAA stroke risk was found in co-dominant (AG vs. AA, OR = 0.76, 95% CI = 0.64-0.91, P = 0.003; GG vs. AA, OR = 0.65, 95% CI = 0.50-0.85, P = 0.002), dominant (AG/GG vs. AA, OR = 0.74, 95% CI = 0.62-0.87, P < 0.001) and recessive models (GG vs. AA/AG, OR = 0.76, 95% CI = 0.59-0.97, P = 0.028) of rs11196288. However, the interaction between age and genotypes of rs11196288 was not statistically significant, and no significant association was observed between the rs11196288A > G polymorphism and short-term outcome of LAA stroke (P > 0.05).

CONCLUSIONS

In the southeastern Chinese population, the rs11196288A > G polymorphism is associated with decreased risk of LAA stroke.

Increased burden of rare deleterious variants of the KCNQ1 gene in patients with large‑vessel ischemic stroke

The impact of rare and damaging variants in genes associated with platelet function in large‑vessel ischemic stroke (LVIS) remains unknown. The aim of this study was to investigate the contribution of some of these variants to the genetic susceptibility to LVIS in Polish patients using a deep re‑sequencing of 54 selected genes, coding for proteins associated with altered platelet function. Targeted pooled re‑sequencing (Illumina HiSeq 2500) was performed on genomic DNA of 500 cases (patients with history of clinically proven diagnosis of LVIS) and 500 age‑, smoking status‑, and sex‑matched controls (no history of any type of stroke), and from the same population as patients with LVIS. After quality control and prioritization based on allele frequency and damaging probability, individual genotyping of all deleterious rare variants was performed in patients from the original cohort, and stratified to concomitant cardiac conditions differing between the study and stroke groups. We demonstrated a statistically significant increase in the number of rare and potentially damaging variants in some of the investigated genes in the LVIS pool (an increase in the genomic variants burden). Furthermore, we identified an association between LVIS and 6 rare functional and damaging variants in the Kv7.1 potassium channel gene (KCNQ1). The predicted functional properties (partial loss‑of function) for the three most damaging variants in KCNQ1 coding locus were further confirmed in vitro by analyzing the membrane potential changes in cell lines co‑transfected heterogeneously with human muscarinic type 1 receptor and wild‑type or mutated KCNQ1 cDNA constructs using fluorescence imaging plate reader. The study demonstrated an increased rare variants burden for 54 genes associated with platelet function, and identified a putative role for rare damaging variants in the KCNQ1 gene on LVIS susceptibility in the Polish population.

Evolutionary concept of inflammatory response and stroke

The immune system plays an important role under both physiological and pathological conditions. Immune surveillance as well as defense and healing processes are crucial for the organism, but the immune system has a natural tendency to act aggressively when excessively stimulated. We may assume that the immune system is not designed to deal with severe conditions, such as polytrauma or severe stroke, because these are not compatible with life in the wilderness and evolution has no chance to act in such cases. These conditions are associated with exaggerated/deregulated inflammatory response, which may cause more damage than initial pathology. In this article, we would like to sketch a basic concept of the immune system-brain interactions from the evolutionary point of view and to discuss some implications related to stroke.

Monogenic, Polygenic, and MicroRNA Markers for Ischemic Stroke

Ischemic stroke (IS) is a leading disease with high mortality and disability, as well as with limited therapeutic window. Biomarkers for earlier diagnosis of IS have long been pursued. Family and twin studies confirm that genetic variations play an important role in IS pathogenesis. Besides DNA mutations found previously by genetic linkage analysis for monogenic IS (Mendelian inheritance), recent studies using genome-wide associated study (GWAS) and microRNA expression profiling have resulted in a large number of DNA and microRNA biomarkers in polygenic IS (sporadic IS), especially in different IS subtypes and imaging phenotypes. The present review summarizes genetic markers discovered by clinical studies and discusses their pathogenic molecular mechanisms involved in developmental or regenerative anomalies of blood vessel walls, neuronal apoptosis, excitotoxic death, inflammation, neurogenesis, and angiogenesis. The possible impact of environment on genetics is addressed as well. We also include a perspective on further studies and clinical application of these IS biomarkers.

AQP4 tag SNPs in patients with intracerebral hemorrhage in Greek and Polish population

BACKROUND

A relatively small number of genetic variants are implicated to pathophysiology of intracerebral hemorrhage (ICH). Aquaporin-4 (AQP4) has been reported to be implicated in the pathophysiological processes of ICH development.

OBJECTIVE

To examine the role of AQP4 gene region polymorphisms on the ICH risk.

METHODS

A total of 250 Greek and 193 Polish patients with primary ICH and 250 and 322 respective controls were enrolled, forming two independent cohorts in order to validate any significant effect. With logistic regression analyses, 7 AQP4 tag single nucleotide polymorphisms (SNPs) were examined for association with ICH risk, lobar/non-lobar ICH risk, and 6-month disability after ICH. Cox regression analysis was applied in order to the effect of AQP4 SNPs on ICH age of onset be tested. Correction for multiple comparisons was applied.

RESULTS

Multivariate logistic regression analysis showed that rs3875089 in the Greek cohort and rs3763043, rs335931 in the Polish cohort had a significant influence on the risk of ICH, lobar and non-lobar ICH. Regarding the age of onset, rs3875089 in the Greek cohort and rs3763043, rs11661256 in the Polish cohort were found to significantly alter the age of onset of ICH and its subtypes. However, all of the above associations did not survive the Bonferroni correction (p-value >0.007). Finally, AQP4 tag SNPs were not found to have any significant effect on long-term disability after ICH.

CONCLUSIONS

In conclusion, the present study provides an indication that AQP4 gene variants may affect susceptibility to primary ICH and may influence the ICH age of onset.

A stroke gene panel for whole-exome sequencing

Extensive analyses of known monogenic causes of stroke by whole-exome/genome sequencing are technically possible today. We here aimed to compile a comprehensive panel of genes associated with monogenic causes of stroke for use in clinical and research situations. We systematically searched the publically available database Online Mendelian Inheritance in Man, and validated the entries against original peer-reviewed publications in PubMed. First, we selected known pathogenic or putatively pathogenic stroke genes reported in at least one person with stroke, and classified the stroke phenotype for each gene into eight subgroups: (1) large artery atherosclerotic, (2) large artery non-atherosclerotic (tortuosity, dolichoectasia, aneurysm, non-atherosclerotic dissection, occlusion), (3) cerebral small-vessel diseases, (4) cardioembolic (arrhythmia, heart defect, cardiomyopathy), (5) coagulation dysfunctions (venous thrombosis, arterial thrombosis, bleeding tendency), (6) intracerebral hemorrhage, (7) vascular malformations (cavernoma, arteriovenous malformations), and (8) metabolism disorders. Second, we selected other genes that may plausibly cause stroke through diseases related to stroke, but without any documented stroke patient description. A third section comprised SNPs associated with stroke in genome-wide association studies (GWAS). We identified in total 214 genes: 120 associated with stroke, 62 associated with diseases that may cause stroke, and 32 stroke-related genes from recent GWAS. We describe these 214 genes and the clinical stroke subtype(s) associated with each of them. The resulting gene panel can be used to interpret exome sequencing results regarding monogenic stroke. Based on the panel's clinical phenotype description, the pathogenicity of novel variants in these genes may be evaluated in specific situations.

NOX4 rs11018628 polymorphism associates with a decreased risk and better short-term recovery of ischemic stroke

Single-nucleotide polymorphisms (SNPs) play an important role in our susceptibility to disease, the severity of illness and the way our body responds to treatment. This study evaluated the impact of three polymorphisms on the susceptibility and functional outcome of ischemic stroke (IS). Three hundred and eight patients and 300 healthy volunteers were enrolled. Polymorphisms of NOX4 rs11018628, MTHFR rs1801133 and NEIL3 rs12645561 were detected in both groups. Smoking (P<0.001), drinking (P<0.001), hypertension (P<0.001) and diabetes (P=0.006), as traditional vascular risk factors for IS, were confirmed in our study. Logistic regression analyses with adjustment for age, sex, smoking, drinking, diabetes, hypertension and total cholesterol showed that the variant genotypes of NOX4 rs11018628 were associated with a significantly decreased risk (Dominant model: OR=0.32, 95% CI=0.22–0.48, P<0.001) and a better short-term recovery of IS (Dominant model: OR=0.57, 95% CI=0.35–0.95, P=0.029). This study demonstrates that the NOX4 rs11018628 SNP is associated with decreased risk in developing IS and better short-term recovery of patients. This suggests that the genetic variant of NOX4 rs11018628 may contribute to the etiology of IS.

Association Between the Apolipoprotein E Gene Polymorphism and Atherosclerotic Middle Cerebral Artery Stenosis

OBJECTIVES

Stenosis of the intracranial large arteries, especially the middle cerebral artery (MCA), is common in the Chinese population. We conducted a case-control study to investigate clinical and apolipoprotein E (ApoE) gene polymorphism of MCA atherosclerosis in the Chinese population.

MATERIALS AND METHODS

Polymerase chain reaction-based protocols were used to identify the genotypes of polymorphisms in ApoE genes. Clinical parameters and the genotypes of polymorphisms in the ApoE genes were compared in patients with and without MCA stenosis. The ApoE exon ε4 genotypes with risk factors were compared in the patients with and without MCA stenosis.

RESULTS

In total, 337 ischemic stroke patients were recruited, 156 cases with and 181 without MCA stenosis. Univariate analysis showed that the levels of systolic blood pressure and pulse pressure were higher in the MCA-stenosis group. There were no significant differences in the genotype and allele frequencies of the ApoE polymorphism observed between patients with and without MCA stenosis. However, there was a trend that the MCA-stenosis group tended to have more of genotype ε4/ε4 (3.8% vs. 0.6%, P=0.052) than the non-MCA-stenosis group. There was no effect of ApoE genotype and genotype-by-environment interactions on ischemic stroke susceptibility.

CONCLUSIONS

This present study indicated that the hypertension (ie, systolic blood pressure and pulse pressure) and the ApoEε4/ε4 genotype may be associated with the occurrence of MCA stenosis in the ischemic stroke Chinese patients.

Genetics of stroke recovery: BDNF val66met polymorphism in stroke recovery and its interaction with aging

Stroke leads to long term sensory, motor and cognitive impairments. Most patients experience some degree of spontaneous recovery which is mostly incomplete and varying greatly among individuals. The variation in recovery outcomes has been attributed to numerous factors including lesion size, corticospinal tract integrity, age, gender and race. It is well accepted that genetics play a crucial role in stroke incidence and accumulating evidence suggests that it is also a significant determinant in recovery. Among the number of genes and variations implicated in stroke recovery the val66met single nucleotide polymorphism (SNP) in the BDNF gene influences post-stroke plasticity in the most significant ways. Val66met is the most well characterized BDNF SNP and is common (40-50 % in Asian and 25-32% in Caucasian populations) in humans. It reduces activity-dependent BDNF release, dampens cortical plasticity and is implicated in numerous diseases. Earlier studies on the effects of val66met on stroke outcome and recovery presented primarily a maladaptive role. Novel findings however indicate a much more intricate interaction between val66met and stroke recovery which appears to be influenced by lesion location, post-stroke stage and age. This review will focus on the role of BDNF and val66met SNP in relation to stroke recovery and try to identify potential pathophysiologic mechanisms involved. The effects of age on val66met associated alterations in plasticity and potential consequences in terms of stroke are also discussed.

Establishment and validation of a prediction model for ischemic stroke risks in patients with type 2 diabetes

AIMS

A risk scoring system for predicting ischemic stroke incidence may identify type 2 diabetes patients at high risk for ischemic stroke who can benefit from preventive intervention programs. Such a risk scoring system can serve as a benchmark to test novel putative risk factors.

METHODS

The study adopted a retrospective cohort, including 28,124 Chinese patients with type 2 diabetes aged 30-84 years during 2001-2004. Participants were randomly assigned to the derivation and validation sets at a 2:1 ratio. Cox's proportional hazard regression model was used to identify risk factors of ischemic stroke incidence in the derivation set. And then the steps proposed by the Framingham Heart Study for establishing an ischemic stroke prediction model with a scoring system was used.

RESULTS

Among 9374 patients in the validation set, 1076 subjects (11.48%) developed ischemic stroke with a mean follow up period of 8.0 years. We identified the following risk factors: age, gender, smoking habit, duration of type 2 diabetes, blood pressure, HbA1c level, total cholesterol to high-density lipoprotein ratio, creatinine, fasting plasma glucose variation (FPG-CV), arterial embolism and thrombosis, diabetes retinopathy, hypoglycemia, anti-diabetes medication use, and cardiovascular medication. The area under receiver operating characteristic curve of the 3-year, 5-year, and 8-year ischemic stroke incidence risks were 0.72, 0.71, and 0.68 for the validation set, respectively.

CONCLUSIONS

This proposed ischemic stroke incidence risk prediction model is the first model established for Chinese patients with type 2 diabetes recruited from nationwide clinical settings.

The relationship between BDNF Val66Met polymorphism and functional mobility in chronic stroke survivors

Background A single nucleotide polymorphism, Val66Met, in the Brain Derived Neurotrophic Factor (BDNF) gene has been studied for its role in recovery following stroke. Despite this work, the role of BDNF genotype on long-term recovery is unclear. Additionally, no study has examined its impact on functional mobility. As a result, the purpose of this study was to examine the relationship between BDNF genotype and functional mobility in chronic stroke survivors by first accounting for factors related to the Val66Met polymorphism and post-stroke recovery. Methods Participants 6 months post-stroke completed the Fugl-Meyer Lower Extremity Assessment (FMLE), Yesavage Geriatric Depression Scale (YGDS), 10 meter walk test (SSWS), and BDNF genotype testing. A regression model was used to determine if including genotype (Val or Met) and the genotype's interactions with age, gender, and depression increased the model's fit in predicting functional mobility, as measured by SSWS, after accounting for physical impairment (FMLE) and personal information (age, gender, and YGDS). Results Sixty-three subjects, twenty-two percent of whom had at least one Met allele, were included. Impairment and personal information significantly predicted SSWS (R² = 0.268, p < 0.001 and ΔR² = 0.158, p = 0.002, respectively). The addition of genotype and genotype's interactions did not significantly increase the variance accounted for in SSWS (ΔR² = 0.012, p = 0.27, and ΔR² = 0.006, p = 0.723, respectively). Conclusions Our results suggest that the Val66Met polymorphism does not predict long-term, functional mobility following stroke. This difference may be due to differences in model variables or a reduced impact of the polymorphism as recovery progresses.

Towards phenotyping stroke: Leveraging data from a large-scale epidemiological study to detect stroke diagnosis

Objective

1) To develop a machine learning approach for detecting stroke cases and subtypes from hospitalization data, 2) to assess algorithm performance and predictors on real-world data collected by a large-scale epidemiology study in the US; and 3) to identify directions for future development of high-precision stroke phenotypic signatures.

Materials and methods

We utilized 8,131 hospitalization events (ICD-9 codes 430–438) collected from the Greater Cincinnati/Northern Kentucky Stroke Study in 2005 and 2010. Detailed information from patients’ medical records was abstracted for each event by trained research nurses. By analyzing the broad list of demographic and clinical variables, the machine learning algorithms predicted whether an event was a stroke case and, if so, the stroke subtype. The performance was validated on gold-standard labels adjudicated by stroke physicians, and results were compared with stroke classifications based on ICD-9 discharge codes, as well as labels determined by study nurses.

Results

The best performing machine learning algorithm achieved a performance of 88.57%/93.81%/92.80%/93.30%/89.84%/98.01% (accuracy/precision/recall/F-measure/area under ROC curve/area under precision-recall curve) on stroke case detection. For detecting stroke subtypes, the algorithm yielded an overall accuracy of 87.39% and greater than 85% precision on individual subtypes. The machine learning algorithms significantly outperformed the ICD-9 method on all measures (P value<0.001). Their performance was comparable to that of study nurses, with better tradeoff between precision and recall. The feature selection uncovered a subset of predictive variables that could facilitate future development of effective stroke phenotyping algorithms.

Discussion and conclusions

By analyzing a broad array of patient data, the machine learning technologies held promise for improving detection of stroke diagnosis, thus unlocking high statistical power for subsequent genetic and genomic studies.

Design and rationale for examining neuroimaging genetics in ischemic stroke: The MRI-GENIE study

OBJECTIVE

To describe the design and rationale for the genetic analysis of acute and chronic cerebrovascular neuroimaging phenotypes detected on clinical MRI in patients with acute ischemic stroke (AIS) within the scope of the MRI-GENetics Interface Exploration (MRI-GENIE) study.

METHODS

MRI-GENIE capitalizes on the existing infrastructure of the Stroke Genetics Network (SiGN). In total, 12 international SiGN sites contributed MRIs of 3,301 patients with AIS. Detailed clinical phenotyping with the web-based Causative Classification of Stroke (CCS) system and genome-wide genotyping data were available for all participants. Neuroimaging analyses include the manual and automated assessments of established MRI markers. A high-throughput MRI analysis pipeline for the automated assessment of cerebrovascular lesions on clinical scans will be developed in a subset of scans for both acute and chronic lesions, validated against gold standard, and applied to all available scans. The extracted neuroimaging phenotypes will improve characterization of acute and chronic cerebrovascular lesions in ischemic stroke, including CCS subtypes, and their effect on functional outcomes after stroke. Moreover, genetic testing will uncover variants associated with acute and chronic MRI manifestations of cerebrovascular disease.

CONCLUSIONS

The MRI-GENIE study aims to develop, validate, and distribute the MRI analysis platform for scans acquired as part of clinical care for patients with AIS, which will lead to (1) novel genetic discoveries in ischemic stroke, (2) strategies for personalized stroke risk assessment, and (3) personalized stroke outcome assessment.

Cerebral Small Vessel Disease Is Associated with Dysregulation in the Ubiquitin Proteasome System and Other Major Cellular Pathways in Specific Brain Regions

BACKGROUND/AIMS

Cerebral small vessel disease (SVD) is characterized by periventricular white matter (WM) changes and can lead to vascular dementia, the second most common form of age-dependent dementia. The pathogenesis of the disease remains poorly understood, and studies of its molecular basis are limited. By profiling gene expression of dissected postmortem brain tissue in SVD patients and comparisons with tissue of nonneurological controls, we aimed to identify genes and processes that are involved in the pathogenesis of SVD to gain new pathogenetic insights.

METHODS

We performed genome-wide expression analyses in postmortem brain tissue samples dissected from frontal, temporal, and occipital lobes as well as basal nuclei comprising thalamus, basal ganglia, and hippocampus from 5 SVD cases and 5 nonaffected control cases. Cellular pathways associated with differently expressed genes were identified in each brain region individually.

RESULTS

This analysis disclosed regional differences, with frontal lobe and thalamus showing the highest numbers of genes with significantly altered expression. Biological functions and pathways associated with changed gene expression depicted brain area-specific defective pathways. Vessel-associated functions, such as increased extracellular matrix-receptor interactions and cell adhesion molecules, were enhanced in all regions. Inflammation and apoptosis were induced particularly in basal nuclei and temporal and occipital regions. Interestingly, genes associated with the ubiquitin-dependent proteolysis (ubiquitin proteasome system) pathway were downregulated in the frontal lobe and in the thalamus, leading to the formation of protein aggregates.

CONCLUSION

This analysis deciphers brain region-specific molecular processes to increase the present knowledge of SVD pathology and determine new potential therapeutic targets.

Arterial Ischemic Stroke in Children and Young Adults

PURPOSE OF REVIEW

This article reviews risk factors, recurrence risk, evaluation, management, and outcomes of arterial ischemic stroke in children and young adults.

RECENT FINDINGS

The risk for recurrence and mortality appear to be low for neonatal and childhood stroke. Most children have relatively mild deficits, but those who have greater neurologic deficits, poststroke epilepsy, or strokes early in life are at risk for lower overall cognitive function. Stroke recurrence and long-term mortality after stroke in young adults are greater than originally thought. Cognitive impairments, depression, and anxiety are associated with higher levels of poststroke unemployment and represent targets for improved poststroke care. Poststroke care in young adults involves more than medical management. Self-reported memory and executive function impairments may be more severe than what is detected by objective measures. Assessment of possible cognitive impairments and appropriate management of psychological comorbidities are key to maximizing the long-term functional outcome of stroke survivors.

SUMMARY

Childhood and young adult stroke survivors survive for many more years than older patients with stroke. To ensure that these survivors maximize the productivity of their lives, neurologists must not only optimize medical management but also recognize that impairments in cognition and mood may be remediable barriers to long-term functional independence.

Hereditary cerebral small vessel disease and stroke

Cerebral small vessel disease is considered hereditary in about 5% of patients and is characterized by lacunar infarcts and white matter hyperintensities on MRI. Several monogenic hereditary diseases causing cerebral small vessel disease and stroke have been identified. The purpose of this systematic review is to provide a guide for determining when to consider molecular genetic testing in patients presenting with small vessel disease and stroke. CADASIL, CARASIL, collagen type IV mutations (including PADMAL), retinal vasculopathy with cerebral leukodystrophy, Fabry disease, hereditary cerebral hemorrhage with amyloidosis, and forkhead box C1 mutations are described in terms of genetics, pathology, clinical manifestation, imaging, and diagnosis. These monogenic disorders are often characterized by early-age stroke, but also by migraine, mood disturbances, vascular dementia and often gait disturbances. Some also present with extra-cerebral manifestations such as microangiopathy of the eyes and kidneys. Many present with clinically recognizable syndromes. Investigations include a thorough family medical history, medical history, neurological examination, neuroimaging, often supplemented by specific examinations e.g of the of vision, retinal changes, as well as kidney and heart function. However molecular genetic analysis is the final gold standard of diagnosis. There are increasing numbers of reports on new monogenic syndromes causing cerebral small vessel disease. Genetic counseling is important. Enzyme replacement therapy is possible in Fabry disease, but treatment options remain overall very limited.

Miconazole protects blood vessels from MMP9-dependent rupture and hemorrhage

Hemorrhagic stroke accounts for 10-15% of all strokes and is strongly associated with mortality and morbidity worldwide, but its prevention and therapeutic interventions remain a major challenge. Here, we report the identification of miconazole as a hemorrhagic suppressor by a small-molecule screen in zebrafish. We found that a hypomorphic mutant fn40a, one of several known β-pix mutant alleles in zebrafish, had the major symptoms of brain hemorrhage, vessel rupture and inflammation as those in hemorrhagic stroke patients. A small-molecule screen with mutant embryos identified the anti-fungal drug miconazole as a potent hemorrhagic suppressor. Miconazole inhibited both brain hemorrhages in zebrafish and mesenteric hemorrhages in rats by decreasing matrix metalloproteinase 9 (MMP9)-dependent vessel rupture. Mechanistically, miconazole downregulated the levels of pErk and Mmp9 to protect vascular integrity in fn40a mutants. Therefore, our findings demonstrate that miconazole protects blood vessels from hemorrhages by downregulating the pERK-MMP9 axis from zebrafish to mammals and shed light on the potential of phenotype-based screens in zebrafish for the discovery of new drug candidates and chemical probes for hemorrhagic stroke.

Summary: A phenotype-based chemical screen in zebrafish identifies miconazole as a novel hemorrhagic suppressor. Miconazole inhibits vessel rupture and hemorrhages by decreasing pErk and MMP9 in zebrafish and rats.

Clinical worthlessness of genetic prediction of common forms of diabetes mellitus and related chronic complications: A position statement of the Italian Society of Diabetology

AIM

We are currently facing several attempts aimed at marketing genetic data for predicting multifactorial diseases, among which diabetes mellitus is one of the more prevalent. The present document primarily aims at providing to practicing physicians a summary of available data regarding the role of genetic information in predicting diabetes and its chronic complications.

DATA SYNTHESIS

Firstly, general information about characteristics and performance of risk prediction tools will be presented in order to help clinicians to get acquainted with basic methodological information related to the subject at issue. Then, as far as type 1 diabetes is concerned, available data indicate that genetic information and counseling may be useful only in families with many affected individuals. However, since no disease prevention is possible, the utility of predicting this form of diabetes is at question. In the case of type 2 diabetes, available data really question the utility of adding genetic information on top of well performing, easy available and inexpensive non-genetic markers. Finally, the possibility of using the few available genetic data on diabetic complications for improving our ability to predict them will also be presented and discussed. For cardiovascular complication, the addition of genetic information to models based on clinical features does not translate in a substantial improvement in risk discrimination. For all other diabetic complications genetic information are currently very poor and cannot, therefore, be used for improving risk stratification.

CONCLUSIONS

In all, nowadays the use of genetic testing for predicting diabetes and its chronic complications is definitively of little value in clinical practice.

Strategies to Enhance Implantation and Survival of Stem Cells After Their Injection in Ischemic Neural Tissue

High post-transplantation cell mortality is the main limitation of various approaches that are aimed at improving regeneration of injured neural tissue by an injection of neural stem cells (NSCs) and mesenchymal stromal cells (MStroCs) in and/or around the lesion. Therefore, it is of paramount importance to identify efficient ways to increase cell transplant viability. We have previously proposed the "evolutionary stem cell paradigm," which explains the association between stem cell anaerobic/microaerophilic metabolic set-up and stem cell self-renewal and inhibition of differentiation. Applying these principles, we have identified the main critical point in the collection and preparation of these cells for experimental therapy: exposure of the cells to atmospheric O₂, that is, to oxygen concentrations that are several times higher than the physiologically relevant ones. In this way, the primitive anaerobic cells become either inactivated or adapted, through commitment and differentiation, to highly aerobic conditions (20%-21% O₂ in atmospheric air). This inadvertently compromises the cells' survival once they are transplanted into normal tissue, especially in the hypoxic/anoxic/ischemic environment, which is typical of central nervous system (CNS) lesions. In addition to the findings suggesting that stem cells can shift to glycolysis and can proliferate in anoxia, recent studies also propose that stem cells may be able to proliferate in completely anaerobic or ischemic conditions by relying on anaerobic mitochondrial respiration. In this systematic review, we propose strategies to enhance the survival of NSCs and MStroCs that are implanted in hypoxic/ischemic neural tissue by harnessing their anaerobic nature and maintaining as well as enhancing their anaerobic properties via appropriate ex vivo conditioning.

Imaging markers of cerebrovascular pathologies: Pathophysiology, clinical presentation, and risk factors

Cerebrovascular pathologies (CVPs) are common pathologies associated with age-related cognitive decline along with Alzheimer disease pathologies. The impact of CVP on the prevalence of dementia is increasingly being recognized. The goal of this review is to improve our understanding of the pathophysiological underpinnings and the multimodal magnetic resonance imaging and positron emission tomography imaging changes that are associated with the hallmarks of CVP. This knowledge will facilitate the development of early detection, intervention, and prevention strategies that may contribute to lowering the risk of dementia. In this review, we will first discuss currently known risk factors of CVPs including cardiovascular, lifestyle, genetic, sex differences, and head injury. Next, we will focus on the pathophysiology of CVPs and their impact on neurodegeneration and downstream cognitive impairment. Specifically, we will discuss three of the most common cerebrovascular lesions seen on MRI: white-matter hyperintensity, microbleeds, and infarcts. Finally, we will discuss the unanswered open questions in this field.

Family health history: an essential starting point for personalized risk assessment and disease prevention

Family health history (FHH) information is well established as a basis for assessing a patient's personal disease risk, but is underutilized for diagnosis and making medical recommendations. Epidemiological and genetic information have heightened the value of FHH to an individual's health. This has motivated the development of new FHH collection tools and strategies for family members, but will require greater awareness and knowledge by both patients and practitioners. FHH will be increasingly important as genomic data become a mainstay of medical diagnostics, since in many cases, a medically important FHH results from lineage-specific genetic variants. The impact of complementary FHH and genomic information will drive the pursuit of personalized and precise targeting of treatments and interventions aimed at maintaining patient health.

Family History and Risk of Recurrent Stroke

Background and Purpose—

The association between family history of stroke and stroke recurrence remains unclear.

Methods—

Using a web-based multicenter stroke registry database, information on history of stroke in first-degree relatives was collected prospectively for acute ischemic stroke patients who were hospitalized within 7 days of onset. The collected information was categorized as follows: type of the affected relative(s) with stroke (paternal, maternal, sibling, or 2 or more) and age of the relative’s stroke onset (<50, 50–59, 60–69, and ≥70 years). Stroke recurrence was captured prospectively using a predetermined protocol. Subgroup analyses were performed according to the patient’s age at the index stroke.

Results—

Among 7642 patients, 937 (12.3%) had a history of stroke in their first-degree relatives and 475 (6.2%: 201 within and 274 after 3 weeks from index stroke) experienced stroke recurrence (median follow-up, 365 days). In multivariable Cox proportional hazard models, overall family history was not associated with stroke recurrence (hazard ratio, 1.08; 95% confidence interval, 0.81–1.43). However, the details of their family histories, including relative’s age at stroke onset (<50 years: hazard ratio, 2.14; 95% confidence interval, 1.004–4.54) and stroke history in a sibling (hazard ratio, 1.67; 95% confidence interval, 1.09–2.58), were independently associated with stroke recurrence after adjusting for potential confounders. The associations appeared to be stronger in young adults with stroke (age, <55 years) than in older stroke patients.

Conclusions—

This study suggests that elevated risks of recurrent stroke are associated with having relatives with early-onset stroke and siblings with stroke histories, implying that additional precautions may be needed in such populations.

Exome array analysis of ischaemic stroke: results from a southern Swedish study

BACKGROUND AND PURPOSE

Genome-wide association (GWA) studies have identified a few risk loci for ischaemic stroke, but these variants explain only a small part of the genetic contribution to the disease. Coding variants associated with amino acid substitutions or premature termination of protein synthesis could have a large effect on disease risk. We performed an exome array analysis for ischaemic stroke.

METHODS

Patients with ischaemic stroke (n = 2385) and control subjects (n = 6077) from three Swedish studies were genotyped with the Illumina HumanOmniExpressExome BeadChip. Single-variant association analysis and gene-based tests were performed of exome variants with minor allele frequency of < 5%. A separate GWA analysis was also performed, based on 700 000 genotyped common markers and subsequent imputation.

RESULTS

No exome variant or gene was significantly associated with all ischaemic stroke after Bonferroni correction (all P > 1.8 × 10^-6 for single-variant and >4.15 × 10^-6 for gene-based analysis). The strongest association in single-variant analysis was found for a missense variant in the DNAH11 gene (rs143362381; P = 5.01 × 10^-6 ). In gene-based tests, the strongest association was for the ZBTB20 gene (P = 7.9 × 10^-5 ). The GWA analysis showed that the sample was homogenous (median genomic inflation factor = 1.006). No genome-wide significant association with overall ischaemic stroke risk was found. However, previously reported associations for the PITX2 and ZFHX3 gene loci with cardioembolic stroke subtype were replicated (P = 7 × 10^-15 and 6 × 10^-3 ).

CONCLUSIONS

This exome array analysis did not identify any single variants or genes reaching the pre-defined significance level for association with ischaemic stroke. Further studies on exome variants should be performed in even larger, well-defined and subtyped samples.

Third European Stroke Science Workshop

Lake Eibsee, Garmisch-Partenkirchen, November 19 to 21, 2015: The European Stroke Organization convened >120 stroke experts from 27 countries to discuss latest results and hot topics in clinical, translational, and basic stroke research. Since its inception in 2011, the European Stroke Science Workshop has become a cornerstone of European Stroke Organization's academic activities and major highlight for researchers in the field. Participants include stroke researchers at all career stages who convene for plenary lectures and discussions, thus facilitating crosstalk among researchers from different fields. As in previous years, the workshop was organized into 7 scientific sessions each focusing on a major research topic. All sessions started with a keynote lecture that provided an overview on current developments and set the scene for the following presentations. The latter were short focused talks on a timely topic and included the most recent findings, including unpublished data. A new element at this year's meeting was a hot topic session in which speakers had to present a provocative concept or update sharply within 5 minutes. In the following, we summarize the key contents of the meeting. The program is provided in the online-only Data Supplement.