From GWAS to the clinic: risk factors for intracranial aneurysms

Racial and Ethnic Differences in Mortality and Functional Outcomes Following Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Ischemic and hemorrhagic stroke incidence tends to be higher among minority racial and ethnic groups. The effect of race and ethnicity following an aneurysmal subarachnoid hemorrhage (aSAH) remains poorly understood. Thus, we aimed to explore the association between race and ethnicity and aSAH outcomes.

METHODS

Single-center retrospective review of patients with aSAH from January 2009 to March 2023. Primary outcome was in-hospital mortality. Secondary outcomes included delayed cerebral ischemia, cerebral infarction, radiographic and symptomatic vasospasm, pulmonary complications, epileptic seizures, external ventricular drain placement, and modified Rankin Scale score at discharge and 3-month follow-up. Associations between race and ethnicity and outcomes were assessed using binary and ordinal regression models, with multivariable models adjusted for significant covariates.

RESULTS

A total of 1325 patients with subarachnoid hemorrhage presented to our center. Among them, 443 cases were excluded, and data from 882 patients with radiographically confirmed aSAH were analyzed. Distribution by race and ethnicity was 40.8% (n=360) White, 31.4% (n=277) Hispanic, 22.1% (n=195) Black, and 5.7% (n=50) Asian. Based on Hunt-Hess and modified Fisher grade, aSAH severity was similar among groups (P=0.269 and P=0.469, respectively). In-hospital mortality rates were highest for Asian (14.0%) and Hispanic (11.2%) patients; however, after adjusting for patient sex, age, health insurance, smoking history, alcohol and substance abuse, and aneurysm treatment, the overall likelihood was comparable to White patients. Hispanic patients had higher risks of developing cerebral infarction (adjusted odds ratio, 2.17 [1.20-3.91]) and symptomatic vasospasm (adjusted odds ratio, 1.64 [1.05-2.56]) than White patients and significantly worse discharge modified Rankin Scale scores (adjusted odds ratio, 1.44 [1.05-1.99]). Non-White patients also demonstrated a lower likelihood of 0 to 2 discharge modified Rankin Scale scores (adjusted odds ratio, 0.71 [0.50-0.98]). No significant interactions between race and ethnicity and age or sex were found for in-hospital mortality and functional outcomes.

CONCLUSIONS

Our study identified significant differences in cerebral infarction and symptomatic vasospasm risk between Hispanic and White patients following aSAH. A higher likelihood of worse functional outcomes at discharge was found among non-White patients. These findings emphasize the need to better understand predisposing risk factors that may influence aSAH outcomes. Efforts toward risk stratification and patient-centered management should be pursued.

PheSeq, a Bayesian deep learning model to enhance and interpret the gene-disease association studies

Despite the abundance of genotype-phenotype association studies, the resulting association outcomes often lack robustness and interpretations. To address these challenges, we introduce PheSeq, a Bayesian deep learning model that enhances and interprets association studies through the integration and perception of phenotype descriptions. By implementing the PheSeq model in three case studies on Alzheimer's disease, breast cancer, and lung cancer, we identify 1024 priority genes for Alzheimer's disease and 818 and 566 genes for breast cancer and lung cancer, respectively. Benefiting from data fusion, these findings represent moderate positive rates, high recall rates, and interpretation in gene-disease association studies.

Genome-Wide Association Study of Clinical Outcome After Aneurysmal Subarachnoid Haemorrhage: Protocol

Aneurysmal subarachnoid haemorrhage (aSAH) results in persistent clinical deficits which prevent survivors from returning to normal daily functioning. Only a small fraction of the variation in clinical outcome following aSAH is explained by known clinical, demographic and imaging variables; meaning additional unknown factors must play a key role in clinical outcome. There is a growing body of evidence that genetic variation is important in determining outcome following aSAH. Understanding genetic determinants of outcome will help to improve prognostic modelling, stratify patients in clinical trials and target novel strategies to treat this devastating disease. This protocol details a two-stage genome-wide association study to identify susceptibility loci for clinical outcome after aSAH using individual patient-level data from multiple international cohorts. Clinical outcome will be assessed using the modified Rankin Scale or Glasgow Outcome Scale at 1–24 months. The stage 1 discovery will involve meta-analysis of individual-level genotypes from different cohorts, controlling for key covariates. Based on statistical significance, supplemented by biological relevance, top single nucleotide polymorphisms will be selected for replication at stage 2. The study has national and local ethical approval. The results of this study will be rapidly communicated to clinicians, researchers and patients through open-access publication(s), presentation(s) at international conferences and via our patient and public network.

Association of Versican Gene Polymorphisms with Intracranial Aneurysm Susceptibility in the Eastern Chinese Population

OBJECTIVE

The proteoglycan versican (VCAN) plays an important role in extracellular matrix (ECM) assembly, and diminished maintenance of the ECM has been increasingly regarded as an important factor in the development of intracranial aneurysms (IAs). Previous studies have revealed that single-nucleotide polymorphisms (SNPs) of the VCAN gene are associated with susceptibility to IAs in European or Japanese populations. However, the association between IA susceptibility and VCAN SNPs in the Eastern Chinese population remains unclear. This study aimed to investigate the associations of the SNPs rs251124, rs2287926, and rs173686 with IA susceptibility in the Eastern Chinese population.

METHODS

A total of 162 patients with IA and 182 controls were enrolled in this study. The study was conducted between January 2017 and December 2020. SNP genotyping for rs251124, rs2287926, and rs173686 was performed using Kompetitive Allele Specific PCR (KASP) after DNA extraction. The SNP data were analysed with CFX Manager Software version 3.1 (Bio-Rad).

RESULTS

rs251124 and rs173686 were significantly associated with susceptibility to IA. The frequency of rs251124-TT in IA was higher than in controls (OR =1.26, 95% CI: 1.07-1.49; P<0.01), and its risk mainly came from the T allele. Furthermore, logistic regression analysis showed that the T/T genotype and T allele of rs251124 were independent risk factors for IA (OR=1.726, 95% CI: 1.136-2.263; P=0.011). Moreover, the G/G genotype and G allele of rs173686 were associated with increased IA susceptibility (OR=2.52, 95% CI: 1.261-5.037; P=0.009).

CONCLUSION

The SNPs rs251124 and rs173686 were strongly associated with genetic susceptibility to IA in the Eastern Chinese population; however, no such association was found in the SNP rs2287926 of VCAN. Our findings suggest that the VCAN gene is an IA susceptible gene that should be further studied as a screening marker for IAs.

Perioperative Management of Aneurysmal Subarachnoid Hemorrhage

Aneurysmal subarachnoid hemorrhage is an acute neurologic emergency. Prompt definitive treatment of the aneurysm by craniotomy and clipping or endovascular intervention with coils and/or stents is needed to prevent rebleeding. Extracranial manifestations of aneurysmal subarachnoid hemorrhage include cardiac dysfunction, neurogenic pulmonary edema, fluid and electrolyte imbalances, and hyperglycemia. Data on the impact of anesthesia on long-term neurologic outcomes of aneurysmal subarachnoid hemorrhage do not exist. Perioperative management should therefore focus on optimizing systemic physiology, facilitating timely definitive treatment, and selecting an anesthetic technique based on patient characteristics, severity of aneurysmal subarachnoid hemorrhage, and the planned intervention and monitoring. Anesthesiologists should be familiar with evoked potential monitoring, electroencephalographic burst suppression, temporary clipping, management of external ventricular drains, adenosine-induced cardiac standstill, and rapid ventricular pacing to effectively care for these patients.

Replication of GWAS Loci Revealed an Increased Risk of BET1L and H19 Polymorphisms with Intracranial Aneurysm

A genome-wide association study (GWAS) identified that BET1L rs2280543 at chromosome 11p15.5 was a susceptibility loci of intracranial aneurysm (IA). Long noncoding RNA H19, located in this region, was reported to play a crucial role in the formation of IA. In this study, we aimed to examine whether BET1L rs2280543 and potentially functional polymorphisms in H19 influence the risk of IA. A hospital-based case-control study was performed involving 542 IA patients and 588 age- and gender-matched controls. The BET1L rs2280543 and H19 polymorphisms were genotyped using the TaqMan assay. The BET1L rs2280543 CT, CT/TT genotypes, and T allele were associated with an increased risk of IA (CT vs. CC, adjusted OR = 1.43, 95% CI: 1.08-1.90, P = 0.01; CT/TT vs. CC, adjusted OR = 1.48, 95% CI: 1.12-1.94, P = 0.005; and T vs. C, adjusted OR = 1.44, 95% CI: 1.13-1.83, P = 0.003). Similarly, the H19 rs217727 TT genotype and T allele were associated with an increased risk of IA (TT vs. CC, adjusted OR = 1.90, 95% CI: 1.35-2.67, P < 0.001; T vs. C, adjusted OR = 1.38, 95% CI: 1.16-1.64, P < 0.001). Combined analyses revealed that the rs2280543 CC-rs217727 CT/TT, rs2280543 CT/TT-rs2735971 GG, and rs217727 CT/TT-rs2735971 GG genotypes were related to the risk of IA. Interaction analysis showed that the 3-loci model of rs2280543-rs217727-rs2839698 contributed to an increased risk of IA. These findings suggest that the GWAS-discovered risk loci BET1L rs2280543 may increase IA susceptibility by interacting with lncRNA H19.

Genetic Risk Factors for Intracranial Aneurysm in the Kazakh Population

An intracranial aneurysm (IA) is a weak or thin area on a blood vessel in the brain that balloons as it fills with blood. Genetic factors can influence the risk of developing an aneurism. The purpose of this study was to explore the relationship between single nucleotide polymorphisms (SNPs) and IA in Kazakh population. The patients were genotyped for 60 single nucleotide polymorphisms. Genotyping was performed on the QuantStudio 12K Flex (Life Technologies). A linear regression analysis found 13 SNPs' significant association with development and rupture of IA: the rs1800956 polymorphism of the ENG gene, rs1756 46 polymorphism of the JDP2 gene, variant rs1800255 of the COL3A1, rs4667622 of the UBR3, rs2374513 of the c12orf75, rs3742321 polymorphism of the StAR, the rs3782356 polymorphism of MLL2 gene, rs3932338 to 214 kilobases downstream of PRDM9, rs7550260 polymorphism of the ARHGEF, rs1504749 polymorphism of the SOX17, the rs173686 polymorphism of CSPG2 gene, rs6460071 located on LIMK1 gene, and the rs4934 polymorphism of SERPINA3. A total of 13 SNPs were identified as potential genetic markers for the development and risk of rupture of aneurysms in the Kazakh population. Similar results were obtained after adjusting for the confounding factors of arterial hypertension and age.

CDKN2BAS gene polymorphisms and the risk of intracranial aneurysm in the Chinese population

Background

CDKN2BAS gene polymorphisms has been shown to correlation with intracranial aneurysm(IA) in the study of foreign people. The study, the author selected the Chinese people as the research object to explore whether CDKN2BAS gene polymorphisms associated with Chinese patients with IA.

Methods

We selected 200 patients(52.69 ± 11.50) with sporadic IA as experimental group, 200 participants(49.99 ± 13.00) over the same period to the hospital without cerebrovascular diseases as control group. Extraction of peripheral blood DNA, applying polymerase chain reaction(PCR)-ligase detection reaction (LDR) identified CDKN2BAS Single nucleotide polymorphism(SNP) locus genotype: rs6475606, rs1333040, rs10757272, rs3217992, rs974336, rs3217986, rs1063192. The differences in allelic and genotype frequencies between the patient and control groups were evaluated by the chi-square test or Fisher’s exact tests.

Results

The genotype of rs1333040 and rs6475606 shown association with sporadic IA(X² = 8.545, P = 0.014; X² = 10.961, P = 0.004; respectively);the C allele of rs6475606 showed reduction the occurrence of IA; the rs1333040 and rs6475606 associated with hemorrhage, the C allele of rs1333040 could lower the risk of hemorrhage, and rs6475606 will not, rs1333040 also associated with aneurysm size.

Conclusion

Our research shows that variant rs1333040 and rs6475606 of CDKN2BAS related to the Chinese han population of sporadic IAs occurs. This study confirms the association between CDKN2BAS and IAs.

Association between angiotensin-converting enzyme insertion/deletion polymorphisms and intracranial aneurysm susceptibility: A meta-analysis

Various studies have evaluated the association between polymorphisms of angiotensin-converting enzyme (ACE) and intracranial aneurysm (IA) risk; however, the results remain inconsistent. The PubMed, Embase, and Wanfang Data databases were systematically searched until January 6th 2016. Case-control studies investigating the association between the ACE polymorphism and IA risk were included. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated with the fixed or random-effects model assuming allele, homozygote comparison of codominant, heterozygote comparison of codominant, dominant, and recessive models. Seven studies including 1,074 cases and 1,500 controls were included in the current meta-analysis. The results of the analysis indicated that the ACE polymorphism significantly increased IA risk in the allele, homozygote comparison of codominant and dominant models. According to the further stratified analysis by ethnicity, source of control and sample sizes, a significant association was identified between the ACE variant and IA risk in Asian individuals, hospital-based, or large (>300) subgroups in all of the genetic models, not including the recessive model. Furthermore, no significantly increased risk was indicated in Caucasian individuals, population-based, or small (<300) subgroups in the heterozygote comparison of codominant, dominant and recessive models. The available evidence indicates that the ACE polymorphism is associated with an increased risk of IA, particularly in Asian individuals. However, other factors may impact this association. Further large, well-designed multicenter studies are required to validate the findings from the present study.

Association between functional polymorphisms in the promoter of the miR-143/145 cluster and risk of intracranial aneurysm

MicroRNAs (miRs)-143/145 are involved in various biological processes related to aneurysm formation and are downregulated in patients with intracranial aneurysm (IA). We aimed to determine whether two functional polymorphisms (i.e. rs4705342 and rs4705343) in the promoter of miR-143/145 are related to IA risk. A case-control study was undertaken to examine the association of rs4705342 and rs4705343 with IA risk, including 565 patients with IA and 622 age- and gender-matched controls. rs4705342 was analysed by TaqMan Assay, and rs4705343 was genotyped using polymerase chain reaction-restriction fragment length polymorphism. miR-143/145 expression was quantified using RT-PCR. rs4705342 was associated with a significantly lower risk of IA, with adjusted ORs of 0.74 (95% CI: 0.58–0.95) for TC genotype carriers and 0.74 (95% CI: 0.59–0.94) for TC/CC genotypes carriers. Individuals carrying the rs4705342 C allele had a reduced risk of IA (adjusted OR = 0.82; 95% CI: 0.68–0.98). Haplotype of the two loci of rs4705342 and rs4705343 showed that the CT haplotype carried a lower IA risk and higher miR-143 level. Moreover, the rs4705342 CC/CT genotypes were associated with higher miR-143 levels. Thus, the rs4705342C-rs4705343T haplotype in the promoter of miR-143/145 cluster may be related to IA development.

Genetic Variants Underlying Risk of Intracranial Aneurysms: Insights from a GWAS in Portugal

Subarachnoid hemorrhage (SAH) is a life-threatening event that most frequently leads to severe disability and death. Its most frequent cause is the rupture of a saccular intracranial aneurysm (IA), which is a blood vessel dilation caused by disease or weakening of the vessel wall. Although the genetic contribution to IA is well established, to date no single gene has been unequivocally identified as responsible for IA formation or rupture. We aimed to identify IA susceptibility genes in the Portuguese population through a pool-based multistage genome-wide association study. Replicate pools were allelotyped in triplicate in a discovery dataset (100 IA cases and 92 gender-matched controls) using the Affymetrix Human SNP Array 6.0. Top SNPs (absolute value of the relative allele score difference between cases and controls |RAS_diff|≥13.0%) were selected for technical validation by individual genotyping in the discovery dataset. From the 101 SNPs successfully genotyped, 99 SNPs were nominally associated with IA. Replication of technically validated SNPs was conducted in an independent replication dataset (100 Portuguese IA cases and 407 controls). rs4667622 (between UBR3 and MYO3B), rs6599001 (between SCN11A and WDR48), rs3932338 (214 kilobases downstream of PRDM9), and rs10943471 (96 kilobases upstream of HTR1B) were associated with IA (unadjusted allelic chi-square tests) in the datasets tested (discovery: 6.84E-04≤P≤1.92E-02, replication: 2.66E-04≤P≤2.28E-02, and combined datasets: 6.05E-05≤P≤5.50E-04). Additionally, we confirmed the known association with IA of rs1333040 at the 9p21.3 genomic region, thus validating our dataset. These novel findings in the Portuguese population warrant further replication in additional independent studies, and provide additional candidates to more comprehensively understand IA etiopathogenesis.

Genetic factors involves in intracranial aneurysms--actualities

Intracranial aneurysm (IA) is a common vascular disorder, which frequently leads to fatal vascular rupture leading to subarachnoid hemorrhage (SAH). Although various acquired risk factors associated with IAs have been identified, heritable conditions are associated with IAs formation but these syndromes account for less than 1% of all IAs in the population. Cerebral aneurysm disease is related to hemodynamic and genetic factors, associated with structural weakness in the arterial wall, which was acquired by a specific, often unknown, event. Possibly, the trigger moment of aneurysm formation may depend on the dynamic arterial growth, which is closely related to aging/ atherosclerosis. Genetic factors are known to have an important role in IA pathogenesis. Literature data provide complementary evidence that the variants on chromosomes 8q and 9p are associated with IA and that the risk of IA in patients with these variants is greatly increased with cigarette smoking. Intracranial aneurysms are acquired lesions (5-10% of the population). In comparison with sporadic aneurysms, familial aneurysms tend to be larger, more often located in the middle cerebral artery, and more likely to be multiple.

ABBREVIATIONS

DNA = deoxyribonucleic acid, FIA = familial Intracranial Aneurysm, GWAS = genome-wide association studies, IL-6 = interleukin-6, ISUIA = International Study of Unruptured Intracranial Aneurysms, IA = Intracranial aneurysm, mRNA = Messager ribonucleic acid, SNPs = single-nucleotide polymorphisms, SMCs = smooth muscle cells, sIAs = sporadic IAs, SAH = subarachnoid hemorrhage, TNF-α = tumor necrosis factor-alpha, COL4A1 = type IV collagen alpha-1.

Anatomic risk factors for middle cerebral artery aneurysm rupture: computed tomography angiography study of 1009 consecutive patients

BACKGROUND

The middle cerebral artery (MCA) is the most frequent location for unruptured intracranial aneurysms. Controversy remains as to which unruptured MCA aneurysms should be treated prophylactically.

OBJECTIVE

To identify independent topographical and morphological variables that could predict increased rupture risk of MCA aneurysms.

METHODS

A retrospective analysis of computed tomography angiography data of 1009 consecutive patients with 1309 MCA aneurysms, referred between 2000 and 2009 to Helsinki University Hospital, was carried out. Morphological and topographical parameters examined for MCA aneurysms comprised aneurysm wall regularity, size, neck width, aspect ratio, bottleneck factor, height-width ratio, location along the MCA, side, distance from the internal carotid artery bifurcation, and dome projection in axial and coronal computed tomography angiography views. Univariate and multivariate logistic regression analyses were performed to determine independent risk factors for rupture.

RESULTS

Of the 1309 MCA aneurysms, 69% were unruptured and 31% were ruptured. Most unruptured MCA aneurysms were smaller than 7 mm (78%), with a smooth wall (80%) and a height-width ratio of 1 (47%) and were located at the main bifurcation (57%). Ruptured MCA aneurysms, mostly 7 to 14 mm in size (55%), had an irregular wall (78%) and a height-width ratio greater than 1 (72%) and were located at the main bifurcation (77%). Thirty-eight percent of MCA bifurcation aneurysms, 74% of large aneurysms, 64% of aneurysms with an irregular wall, and 49% of aneurysms with a height-width ratio greater than 1 were ruptured.

CONCLUSION

Location at the main MCA bifurcation, wall irregularity, and less spherical geometry were independently associated with rupture of MCA aneurysms with a correlation with aneurysm size. artery.

Risk of subarachnoid haemorrhage in people admitted to hospital with selected immune-mediated diseases: record-linkage studies

Background

Subarachnoid hemorrhage (SAH) is a devastating cause of stroke, occurring in relatively young people. It has been suggested that some immune-mediated diseases may be associated with an increased risk of SAH.

Methods

We analysed a database of linked statistical records of hospital admissions and death certificates for the whole of England (1999–2011). Rate ratios for SAH were determined, comparing immune-mediated disease cohorts with comparison cohorts.

Results

There were significantly elevated risks of SAH after hospital admission for the following individual immune-mediated diseases: Addison’s disease, ankylosing spondylitis, autoimmune haemolytic anaemia, Crohn’s disease, diabetes mellitus, idiopathic thrombocytopenia purpura, myxoedema, pernicious anaemia, primary biliary cirrhosis, psoriasis, rheumatoid arthritis, scleroderma, Sjogren’s syndrome, SLE and thyrotoxicosis. Elevated risks that were greater than 2-fold were found for Addison’s disease (rate ratio (RR) = 2.01, 95% confidence interval 1.3-2.97), idiopathic thrombocytopenia purpura (RR = 2.42, 1.86-3.11), primary biliary cirrhosis (RR = 2.21, 1.43-3.16) and SLE (RR = 3.76, 3.08-4.55).

Conclusions

Our findings strongly support the suggestion that patients with some immune-mediated diseases have an increased risk of SAH. Further studies of the mechanisms behind this association are warranted.

MicroRNA/mRNA profiling and regulatory network of intracranial aneurysm

Background

Intracranial aneurysm (IA) is one of the most lethal forms of cerebrovascular diseases characterized by endothelial dysfunction, vascular smooth muscle cell phenotypic modulation, inflammation and consequently loss of vessel cells and extracellular matrix degradation. Besides environmental factors, genetics seem to be a very important factor in the genesis of this disease. Previous mRNA expression studies revealed a large number of differentially expressed genes between IA and control tissue. However, microRNAs (miRNA), small non-coding RNAs which are post-transcriptional regulators of gene expression, have been barely studied. Studying miRNAs could provide a hypothetical mechanism underlying rupture of IA.

Methods

A microarray study was carried out to determine difference in microRNAs and mRNA between patients’ IA tissues and controls. Quantitative RT-PCR assay compared the expression level between two groups (14 IA domes vs. 14 controls) were used for validation. Validated miRNAs were analyzed using Ingenuity Pathway Analysis (IPA) to identify the networks and pathways.

Results

18 miRNAs were confirmed by qPCR to be robustly down-regulated in 14 ruptured IA patients including hsa-mir-133b, hsa-mir-133a, hsa-mir-1, hsa-mir-143-3p, hsa-mir-145-3p, hsa-mir-145-5p, hsa-mir-455-5p, hsa-mir-143-5p, hsa-mir-23b-3p etc., of which 11 miRNAs are clusters: hsa-mir-1/has-mir-133a, hsa-mir-143/hsa-mir-145, hsa-mir-23b/hsa-mir-24-1, and hsa-mir-29b-2/hsa-mir-29c. 12 predicted functions were generated using IPA which showed significant associations with migration of phagocytes, proliferation of mononuclear leukocytes, cell movement of mononuclear leukocytes, cell movement of smooth muscle cells etc.

Conclusion

These data support common disease mechanisms that may be under miRNA control and provide exciting directions for further investigations aimed at elucidating the miRNA mechanisms and targets that may yield new therapies for IA.

The association between interleukin-6 gene polymorphisms and intracranial aneurysms: a meta-analysis

BACKGROUND

Interleukin-6 (IL-6) is an important proinflammatory cytokine, and some studies have demonstrated that IL-6 promoter polymorphisms (-174G/C and -572G/C) may be associated with intracranial aneurysms. A meta-analysis based on the evidence currently available from the literature was conducted to make a more precise estimation of this relationship.

METHODS

Electronic databases (the National Library of Medline and Embase databases) were searched before June 2013. Odds ratio (OR) and 95% confidence interval (CI) were calculated in fixed- or random-effects models when appropriate. Subgroup analyses were performed by race. This meta-analysis included six case-control studies, which included 1188 intracranial aneurysms cases and 4099 controls.

RESULTS

The combined results based on all studies showed that intracranial aneurysms cases had a significantly lower frequency of -572CC [OR (Recessive model) = 0.47, 95% CI = 0.36, 0.60, P < 0.001; OR (Codominant model) = 0.29, 95% CI = 0.20, 0.44, P < 0.001], -572GC [OR (Codominant model) = 0.73, 95% CI = 0.55, 0.98, P = 0.04] and -174CC [OR (Recessive model) = 0.73, 95% CI = 0.54, 0.98, P = 0.03; OR (Codominant model) = 0.70, 95% CI = 0.51, 0.97, P = 0.03] genotype. In the subgroup analysis by race, we found that (1) intracranial aneurysms cases had a significantly lower frequency of -572CC [OR (Recessive model) = 0.41, 95% CI = 0.32, 0.53, P < 0.001; OR (Codominant model) = 0.18, 95% CI = 0.12, 0.29, P < 0.001] and -572GC [OR (Codominant model) = 0.61, 95% CI = 0.42, 0.88, P = 0.009] genotype in Asians; (2) intracranial aneurysms cases had a significantly higher frequency of -572CC [OR (Recessive model) = 4.41, 95% CI = 1.35, 14.36, P = 0.01; OR (Codominant model) = 4.41, 95% CI = 1.35, 14.38, P = 0.01] genotype and lower frequency of -174CC [OR (Recessive model) = 0.73, 95% CI = 0.54, 0.98, P = 0.03; OR (Codominant model) = 0.70, 95% CI = 0.51, 0.97, P = 0.03] genotype in Caucasians.

CONCLUSIONS

Our meta-analysis suggested that IL-6 promoter polymorphisms (-174G/C and -572G/C) were associated with intracranial aneurysms. However, due to the small subjects included in analysis and the selection bias in some studies, the results should be interpreted with caution.

The identification of pathway markers in intracranial aneurysm using genome-wide association data from two different populations

The identification of significant individual factors causing complex diseases is challenging in genome-wide association studies (GWAS) since each factor has only a modest effect on the disease development mechanism. In this study, we hypothesize that the biological pathways that are targeted by these individual factors show higher conservation within and across populations. To test this hypothesis, we searched for the disease related pathways on two intracranial aneurysm GWAS in European and Japanese case-control cohorts. Even though there were a few significantly conserved SNPs within and between populations, seven of the top ten affected pathways were found significant in both populations. The probability of random occurrence of such an event is 2.44E-36. We therefore claim that even though each individual has a unique combination of factors involved in the mechanism of disease development, most targeted pathways that need to be altered by these factors are, for the most part, the same. These pathways can serve as disease markers. Individuals, for example, can be scanned for factors affecting the genes in marker pathways. Hence, individual factors of disease development can be determined; and this knowledge can be exploited for drug development and personalized therapeutic applications. Here, we discuss the potential avenues of pathway markers in medicine and their translation to preventive and individualized health care.

Unruptured intracranial aneurysms in the Familial Intracranial Aneurysm and International Study of Unruptured Intracranial Aneurysms cohorts: differences in multiplicity and location

OBJECT

Familial predisposition is a recognized nonmodifiable risk factor for the formation and rupture of intracranial aneurysms (IAs). However, data regarding the characteristics of familial IAs are limited. The authors sought to describe familial IAs more fully, and to compare their characteristics with a large cohort of nonfamilial IAs.

METHODS

The Familial Intracranial Aneurysm (FIA) study is a multicenter international study with the goal of identifying genetic and other risk factors for formation and rupture of IAs in a highly enriched population. The authors compared the FIA study cohort with the International Study of Unruptured Intracranial Aneurysms (ISUIA) cohort with regard to patient demographic data, IA location, and IA multiplicity. To improve comparability, all patients in the ISUIA who had a family history of IAs or subarachnoid hemorrhage were excluded, as well as all patients in both cohorts who had a ruptured IA prior to study entry.

RESULTS

Of 983 patients enrolled in the FIA study with definite or probable IAs, 511 met the inclusion criteria for this analysis. Of the 4059 patients in the ISUIA study, 983 had a previous IA rupture and 657 of the remainder had a positive family history, leaving 2419 individuals in the analysis. Multiplicity was more common in the FIA patients (35.6% vs 27.9%, p<0.001). The FIA patients had a higher proportion of IAs located in the middle cerebral artery (28.6% vs 24.9%), whereas ISUIA patients had a higher proportion of posterior communicating artery IAs (13.7% vs 8.2%, p=0.016).

CONCLUSIONS

Heritable structural vulnerability may account for differences in IA multiplicity and location. Important investigations into the underlying genetic mechanisms of IA formation are ongoing.