Familial intracranial aneurysms: an analysis of 346 multiplex Finnish families

Factors associated with early-onset intracranial aneurysms in patients with autosomal dominant polycystic kidney disease

BACKGROUND

Recently, the importance of attribute-based medicine has been emphasized. The effects of early-onset intracranial aneurysms on patients can be significant and long-lasting. Herein, we compared the factors associated with intracranial aneurysms in patients with autosomal dominant polycystic kidney disease (ADPKD) according to age categories (≥ 50 years, < 50 years).

METHODS

We included 519 ADPKD patients, with a median age of 44 years, estimated glomerular filtration rate of 54.5 mL/min/1.73 m2, and total follow-up duration of 3104 patient-years. Logistic regression analyses were performed to determine factors associated with intracranial aneurysms.

RESULTS

Regarding the presence of intracranial aneurysm, significant interactions were identified between the age category (age ≥ 50 years), female sex (P = 0.0027 for the interaction) and hypertension (P = 0.0074 for the interaction). Female sex and hypertension were associated with intracranial aneurysm risk factors only in patients aged ≥ 50 years. The presence of intracranial aneurysm was significantly associated with chronic kidney disease (CKD) stages 4-5 (odds ratio [OR] = 3.87, P = 0.0007) and family history of intracranial aneurysm or subarachnoid hemorrhage (OR = 2.30, P = 0.0217) in patients aged < 50 years. For patients aged ≥ 50 years, in addition to the abovementioned factors [OR = 2.38, P = 0.0355 for CKD stages 4-5; OR = 3.49, P = 0.0094 for family history of intracranial aneurysm or subarachnoid hemorrhage], female sex (OR = 4.51, P = 0.0005), and hypertension (OR = 5.89, P = 0.0012) were also associated with intracranial aneurysm.

CONCLUSION

Kidney dysfunction and family history of intracranial aneurysm or subarachnoid hemorrhage are risk factors for early-onset intracranial aneurysm. Patients aged < 50 years with a family history of intracranial aneurysm or subarachnoid hemorrhage or with CKD stages 4-5 may be at an increased risk of early-onset intracranial aneurysm.

Number of Affected Relatives, Age, Smoking, and Hypertension Prediction Score for Intracranial Aneurysms in Persons With a Family History for Subarachnoid Hemorrhage

Persons with a positive family history of aneurysmal subarachnoid hemorrhage are at increased risk of aneurysmal subarachnoid hemorrhage. Preventive screening for intracranial aneurysms (IAs) in these persons is cost-effective but not very efficient. We aimed to develop and externally validate a model for predicting the probability of an IA at first screening in persons with a positive family history of aneurysmal subarachnoid hemorrhage.

Familial Intracranial Aneurysm in Newfoundland: Clinical and Genetic Analysis

Objective:

Intracranial aneurysm (IA) is an expansion of the weakened arterial wall that is often asymptomatic until rupture, resulting in subarachnoid hemorrhage. Here we describe the high prevalence of familial IA in a cohort of Newfoundland ancestry. We began to investigate the genetic etiology of IA in affected family members, as the inheritance of this disease is poorly understood.

Methods:

Whole exome sequencing was completed for a cohort of 12 affected individuals from two multiplex families with a strong family history of IA. A filtering strategy was implemented to identify rare, shared variants. Filtered variants were prioritized based on validation by Sanger sequencing and segregation within the families.

Results:

In family R1352, six variants passed filtering; while in family R1256, 68 variants remained, so further filtering was pursued. Following validation by Sanger sequencing, top candidates were investigated in a set of population controls, namely,C4orf6c.A1G (p.M1V) andSPDYE4c.C103T (p.P35S). Neither was detected in 100 Newfoundland control samples.

Conclusion:

Rare and potentially deleterious variants were identified in both families, though incomplete segregation was identified for all filtered variants. Alternate methods of variant prioritization and broader considerations regarding the interplay of genetic and environmental factors are necessary in future studies of this disease.

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.

Neuroprotective Agents in the Intensive Care Unit: -Neuroprotective Agents in ICU

Neuroprotection or prevention of neuronal loss is a complicated molecular process that is mediated by various cellular pathways. Use of different pharmacological agents as neuroprotectants has been reported especially in the last decades. These neuroprotective agents act through inhibition of inflammatory processes and apoptosis, attenuation of oxidative stress and reduction of free radicals. Control of this injurious molecular process is essential to the reduction of neuronal injuries and is associated with improved functional outcomes and recovery of the patients admitted to the intensive care unit. This study reviews neuroprotective agents and their mechanisms of action against central nervous system damages.

Familial Intracranial Aneurysms in Saudi Arabia: What Do We Need To Do?

Aneurysmal subarachnoid hemorrhage (SAH) is a devastating event with significant morbidity and mortality. The incidence of SAH might be influenced by environmental factors but genetic predisposition is evolving as an important effector in the risk of development of intracranial aneurysms and rupture of aneurysms. This requires strategies for effective screening of family members at risk of developing such a phenotype, in order to deliver preventive treatment to these target lesions. We discuss the potential for implementing these strategies in the Saudi Arabian health system and the future implications on our care for such a vulnerable group of subjects.

A 54-year-old man with 12 intracranial aneurysms and familial subarachnoid hemorrhage: case report

Unruptured intracranial aneurysms occur in 1-3 % of the general population, and the risk of rupture is generally considered to be low. However, patients with multiple aneurysms and familial predisposition carry a particular risk of subarachnoid hemorrhage (SAH). A 54-year-old hypertensive man underwent screening with a head CT angiography (CTA) because of his comorbidities. CTA revealed multiple bilateral aneurysms around the circle of Willis. At first surgery, seven aneurysms were clipped (BA, ACOM, ICA ×2, and MCA ×3), two of which were detected intraoperatively only. During the second surgery, another three aneurysms were surgically clipped (PCOM and MCA ×2), one of which was detected intraoperatively. Follow-up angiography revealed another two aneurysms. A PCOM aneurysm was treated by coil embolization and a VA aneurysm clipped surgically during a third admission. The patient made an uneventful recovery. However, 4 months after his second surgery, his daughter underwent surgical clipping of a right-sided ICA aneurysm. This case report highlights both the importance of screening of high risk patients with family history of SAH, as well as its limitations, as our patient developed two de novo aneurysms during 6-month follow-up and CTA preoperatively missed three small aneurysms.

A Potential Polymorphism in the Promoter of Let-7 is Associated With an Increased Risk of Intracranial Aneurysm: A Case-Control Study

Let-7 family plays a key role in the progression of atherosclerosis and intracranial aneurysm (IA). We hypothesized that rs10877887 and rs13293512 polymorphisms in the promoters of let-7 family may be associated with the susceptibility of IA. We genotyped the 2 single nucleotide polymorphisms (SNPs) in 305 patients with IA and 401 healthy controls. The rs10877887 was analyzed using a polymerase chain reaction-restriction fragment length polymorphism assay, and the rs13293512 was analyzed using a TaqMan SNP genotyping method. The relative expression of let-7 family was measured in plasma of cases and controls using real-time PCR. We found that the rs13293512CT genotype was associated with a significantly increased risk of developing IA in a heterozygote comparison (adjusted OR = 1.43, 95% CI, 1.00-2.05, P = 0.048) and dominant comparison (adjusted OR = 1.44, 95% CI, 1.02-2.03, P = 0.04). Combined analysis showed that the rs10877887TT and rs13293512CC/CT genotypes had a significantly increased risk of IA (OR = 1.67, 95% CI, 1.04-2.68, P = 0.03). Moreover, the levels of let-7a, let-7d, and let-7f were downregulated in IA patients, and patients with the rs13293512CC/CT genotypes had a lower level of let-7a than those with rs13293512TT genotype (P = 0.03). These findings indicate that the rs13293512CC/CT is a risk factor for the development of IA, possibly because of the genotypes resulting in a lower level of let-7a.

Guidelines for the Management of Patients With Unruptured Intracranial Aneurysms: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association

PURPOSE

The aim of this updated statement is to provide comprehensive and evidence-based recommendations for management of patients with unruptured intracranial aneurysms.

METHODS

Writing group members used systematic literature reviews from January 1977 up to June 2014. They also reviewed contemporary published evidence-based guidelines, personal files, and published expert opinion to summarize existing evidence, indicate gaps in current knowledge, and when appropriate, formulated recommendations using standard American Heart Association criteria. The guideline underwent extensive peer review, including review by the Stroke Council Leadership and Stroke Scientific Statement Oversight Committees, before consideration and approval by the American Heart Association Science Advisory and Coordinating Committee.

RESULTS

Evidence-based guidelines are presented for the care of patients presenting with unruptured intracranial aneurysms. The guidelines address presentation, natural history, epidemiology, risk factors, screening, diagnosis, imaging and outcomes from surgical and endovascular treatment.

Sex-related clustering of intracranial aneurysms within families

BACKGROUND AND PURPOSE

Family history is important risk factor for intracranial aneurysms (ICA), but the pattern of inheritance is unsettled. If ICA within families would cluster according to sex, this may have implications for risk prediction and screening advice within families. We assessed the relationship between the sex of probands and their affected first-degree relatives (FDRs) within families with ICA.

METHODS

We used data from our prospectively collected database of families with known familial ICA. We calculated relative risks for a female affected proband having a female affected FDR as compared with a male affected proband having female affected FDR with corresponding 95% confidence intervals.

RESULTS

We included 148 families with 376 affected FDR. For a female proband the relative risk for having a female affected FDR compared with a male proband having an affected female FDR was 1.2 (95% confidence interval, 1.0-1.6).

CONCLUSIONS

The clustering of ICA within families is greater in women than in men, with an excess of affected female FDR in female probands. However, because this excess is modest, our findings indicate that sex is not a relevant factor in risk prediction or screening advice in families with ICA.

Molecular basis and genetic predisposition to intracranial aneurysm

Intracranial aneurysms, also called cerebral aneurysms, are dilatations in the arteries that supply blood to the brain. Rupture of an intracranial aneurysm leads to a subarachnoid hemorrhage, which is fatal in about 50% of the cases. Intracranial aneurysms can be repaired surgically or endovascularly, or by combining these two treatment modalities. They are relatively common with an estimated prevalence of unruptured aneurysms of 2%-6% in the adult population, and are considered a complex disease with both genetic and environmental risk factors. Known risk factors include smoking, hypertension, increasing age, and positive family history for intracranial aneurysms. Identifying the molecular mechanisms underlying the pathogenesis of intracranial aneurysms is complex. Genome-wide approaches such as DNA linkage and genetic association studies, as well as microarray-based mRNA expression studies, provide unbiased approaches to identify genetic risk factors and dissecting the molecular pathobiology of intracranial aneurysms. The ultimate goal of these studies is to use the information in clinical practice to predict an individual's risk for developing an aneurysm or monitor its growth or rupture risk. Another important goal is to design new therapies based on the information on mechanisms of disease processes to prevent the development or halt the progression of intracranial aneurysms.

Long-term, serial screening for intracranial aneurysms in individuals with a family history of aneurysmal subarachnoid haemorrhage: a cohort study

BACKGROUND

Individuals with two or more first-degree relatives who have had aneurysmal subarachnoid haemorrhage (aSAH) have an increased risk of aneurysms and aSAH. We investigated the yield of long-term serial screening for intracranial aneurysms in these individuals.

METHODS

In a cohort study, we reviewed the results of screening of individuals with a positive family history of aSAH (two or more first-degree relatives who had had aSAH or unruptured intracranial aneurysms) done at the University Medical Centre Utrecht (Utrecht, Netherlands) between April 1, 1993, and April 1, 2013. Magnetic resonance angiography or CT angiography was done from age 16-18 years to 65-70 years. After a negative screen, we advised individuals to contact us after 5 years, but did not actively call them for repeated screening. We recorded familial history of ruptured and unruptured intracranial aneurysms, smoking history, hypertension, previous aneurysms, screening dates, and screening results. We identified risk factors for positive initial and follow-up screens with univariable and multivariable regression analysis.

FINDINGS

We identified aneurysms in 51 (11%, 95% CI 9-14) of 458 individuals at first screening, in 21 (8%, 5-12) of 261 at second screening, in seven (5%, 2-11) of 128 at third screening, and three (5%, 1-14) of 63 at fourth screening. Five (3%, 95% CI 1-6) of 188 individuals without a history of aneurysms and with two negative screens had a de-novo aneurysm in a follow-up screen. Smoking (odds ratio 2·7, 95% CI 1·2-5·9), history of previous aneurysms (3·9, 1·2-12·7), and familial history of aneurysms (3·5, 1·6-8·1) were significant risk factors for aneurysms at first screening in the multivariable analysis. History of previous aneurysms was the only significant risk factor for aneurysms at follow-up screening (hazard ratio 4·5, 1·1-18·7). Aneurysms were identified in six (5%, 95% CI 2-10) of 129 individuals who were screened before age 30 years. One patient developed a de-novo aneurysm that ruptured 3 years after the last negative screen.

INTERPRETATION

In individuals with a family history of aSAH, the yield of long-term screening is substantial even after more than 10 years of follow-up and two initial negative screens. We advocate long-term serial screening in these individuals, although the risk of aSAH within screening intervals is not eliminated.

FUNDING

The Dutch Heart Foundation.

Concordant Symptomatic Intracranial Aneurysm in a Monozygotic Twin: A Case Report and Review of the Literature

The development of an intracranial aneurysm (IA) is a multifactorial process, involving genetic and environmental factors. The presence of IA or aneurysmal subarachnoid hemorrhage (aSAH) in twins is particularly interesting, since both genetic and environmental factors can be studied. It also raises the question of whether, when one twin is affected, the other asymptomatic twin should be examined for an IA. We report on a monozygotic (MZ) twin-pair with aSAH in both twins and we review all reported cases of IA in MZ twins. Including our case, we found only 14 MZ twin-pairs in which both twins harbored an IA, suggesting a heavy underreporting in the medical literature. In this small group, a high concordance was noted in the sites of IAs. In MZ twins, the preferred sites for IAs are the branching arteries, while aneurysms arising from fusion arteries are rare. These sites differ from the preferential sites seen in series of familial IAs and series of sporadic IAs. We therefore hypothesize that the twinning process might play a significant role in the development of IAs in MZ twins. To further explore and substantiate this, the large twin registries should be studied. Although IAs in MZ twins with a negative family history for IAs should not be regarded as familial IAs, screening of the asymptomatic twin should be seriously considered if one MZ twin presents with an aSAH or an IA, because of the high fatality rates reported in asymptomatic (and not screened) MZ twin-halves.

Intracranial aneurysms: optimized diagnostic tools call for thorough interdisciplinary treatment strategies

OBJECTIVE

Intracranial aneurysms (IAs) require deliberately selected treatment strategies as they are incrementally found prior to rupture and deleterious subarachnoid haemorrhage (SAH). Multiple and recurrent aneurysms necessitate both neurointerventionalists and neurosurgeons to optimize aneurysmal occlusion in an interdisciplinary effort. The present study was conducted to condense essential strategies from a single neurovascular centre with regard to the lessons learned.

METHOD

Medical charts of 321 consecutive patients treated for IAs at our centre from September 2008 until December 2010 were retrospectively analysed for clinical presentation of the aneurysms, multiplicity and treatment pathways. In addition, a selective Medline search was performed.

RESULTS

A total of 321 patients with 492 aneurysms underwent occlusion of their symptomatic aneurysm: 132 (41.1%) individuals were treated surgically, 189 (58.2%) interventionally; 138 patients presented with a SAH, of these 44.2% were clipped and 55.8% were coiled. Aneurysms of the middle cerebral artery were primarily occluded surgically (88), whereas most of the aneurysms of the internal carotid artery and anterior communicating artery (114) were treated endovascularly. Multiple aneurysms (range 2-5 aneurysms/individual) were diagnosed in 98 patients (30.2%). During the study period 12 patients with recurrent aneurysms were allocated to another treatment modality (previously clip to coil and vice versa).

CONCLUSIONS

Our data show that successful interdisciplinary occlusion of IAs is based on both neurosurgical and neurointerventional therapy. In particular, multiple and recurrent aneurysms require tailored individual approaches to aneurysmal occlusion. This is achieved by a consequent interdisciplinary pondering of the optimal strategy to occlude IAs in order to prevent SAH.

Morphology parameters for intracranial aneurysm rupture risk assessment

OBJECTIVE

The aim of this study is to identify image-based morphological parameters that correlate with human intracranial aneurysm (IA) rupture.

METHODS

For 45 patients with terminal or sidewall saccular IAs (25 unruptured, 20 ruptured), three-dimensional geometries were evaluated for a range of morphological parameters. In addition to five previously studied parameters (aspect ratio, aneurysm size, ellipticity index, nonsphericity index, and undulation index), we defined three novel parameters incorporating the parent vessel geometry (vessel angle, aneurysm [inclination] angle, and [aneurysm-to-vessel] size ratio) and explored their correlation with aneurysm rupture. Parameters were analyzed with a two-tailed independent Student's t test for significance; significant parameters (P < 0.05) were further examined by multivariate logistic regression analysis. Additionally, receiver operating characteristic analyses were performed on each parameter.

RESULTS

Statistically significant differences were found between mean values in ruptured and unruptured groups for size ratio, undulation index, nonsphericity index, ellipticity index, aneurysm angle, and aspect ratio. Logistic regression analysis further revealed that size ratio (odds ratio, 1.41; 95% confidence interval, 1.03-1.92) and undulation index (odds ratio, 1.51; 95% confidence interval, 1.08-2.11) had the strongest independent correlation with ruptured IA. From the receiver operating characteristic analysis, size ratio and aneurysm angle had the highest area under the curve values of 0.83 and 0.85, respectively.

CONCLUSION

Size ratio and aneurysm angle are promising new morphological metrics for IA rupture risk assessment. Because these parameters account for vessel geometry, they may bridge the gap between morphological studies and more qualitative location-based studies.

Sequencing of TGF-beta pathway genes in familial cases of intracranial aneurysm

BACKGROUND AND PURPOSE

Familial aggregation of intracranial aneurysms (IA) strongly suggests a genetic contribution to pathogenesis. However, genetic risk factors have yet to be defined. For families affected by aortic aneurysms, specific gene variants have been identified, many affecting the receptors to transforming growth factor-beta (TGF-beta). In recent work, we found that aortic and intracranial aneurysms may share a common genetic basis in some families. We hypothesized, therefore, that mutations in TGF-beta receptors might also play a role in IA pathogenesis.

METHODS

To identify genetic variants in TGF-beta and its receptors, TGFB1, TGFBR1, TGFBR2, ACVR1, TGFBR3, and ENG were directly sequenced in 44 unrelated patients with familial IA. Novel variants were confirmed by restriction digestion analyses, and allele frequencies were analyzed in cases versus individuals without known intracranial disease. Similarly, allele frequencies of a subset of known SNPs in each gene were also analyzed for association with IA.

RESULTS

No mutations were found in TGFB1, TGFBR1, TGFBR2, or ACVR1. Novel variants identified in ENG (p.A60E) and TGFBR3 (p.W112R) were not detected in at least 892 reference chromosomes. ENG p.A60E showed significant association with familial IA in case-control studies (P=0.0080). No association with IA could be found for any of the known polymorphisms tested.

CONCLUSIONS

Mutations in TGF-beta receptor genes are not a major cause of IA. However, we identified rare variants in ENG and TGFBR3 that may be important for IA pathogenesis in a subset of families.

Genomewide Linkage in a Large Caucasian Family Maps a New Locus for Intracranial Aneurysms to Chromosome 13q

Background and Purpose— Familial aggregation of intracranial aneurysms (IAs) indicates a genetic role in the pathogenesis of this disease. Despite a number of reported susceptibility loci, no disease-causing gene variants have been identified. In this study, we used a parametric genomewide linkage approach to search for new IA susceptibility loci in a large Caucasian family.

Methods— The affection status of family members with clinical signs of IA was confirmed with medical records or through radiological or surgical examinations. All other relatives were screened using MR angiography. Genomewide linkage analysis was performed on 35 subjects using approximately 250 000 single nucleotide polymorphic markers.

Results— Ten individuals had an IA. Linkage analysis using a dominant model showed significant linkage to a 7-cM region in 13q14.12–21.1 with a maximum logarithm of odds score of 4.56.

Conclusion— A new IA susceptibility locus on 13q was identified, adding to the number of IA loci already reported. Given that no coding variants have been reported to date, it is possible that alternative genetic variants such as regulatory elements or copy number variation are important in IA pathogenesis. We are proceeding with attempts to identify such variants in our locus.

Polymorphism rs42524 of COL1A2 and sporadic intracranial aneurysms in the Chinese population

Object

The COL1A2 gene at 7q22.1 has been shown to be associated with familial intracranial aneurysms (IAs) in the Japanese population. In the present study, the authors investigated the correlation between the presence of the rs42524 polymorphism in COL1A2 and the occurrence of sporadic IAs in Chinese patients.

Methods

The polymorphism rs42524 of the COL1A2 gene was identified by polymerase chain reaction–based restriction analysis in genomic DNA from 226 patients with sporadic IAs (mean age 51.49 ± 11.47 years) and 326 control participants (mean age 52.33 ± 10.50 years). Neurological assessments were performed using the Hunt and Hess grading system, and differences in allelic and genotypic frequencies between the patient and control groups were evaluated with the chi-square test.

Results

There was a significant difference in either the genotype distribution (χ2 = 11.99, p = 0.002) or allelic frequencies (χ2 = 11.96, p = 0.001, odds ratio 2.579, 95% confidence interval 1.486–4.476) between patients with IAs and patients in the control group.

Conclusions

The rs42524 polymorphism of COL1A2 could be a genetic risk factor for sporadic IAs among individuals of Chinese Han ethnicity. This study is the first to confirm the association between COL1A2 and IAs.

Molecular Genetics of Human Intracranial Aneurysms

Intracranial aneurysms (IAs) are the dilatations of blood vessels in the brain and pose potential risk of rupture leading to subarachnoid hemorrhage. Although the genetic basis of IAs is poorly understood, it is well-known that genetic factors play an important part in the pathogenesis of IAs. Therefore, the identifying susceptible genetic variants might lead to the understanding of the mechanism of formation and rupture of IAs and might also lead to the development of a pharmacological therapy. To elucidate the molecular pathogenesis of diseases has become a crucial step in the development of new treatment strategies. Although extensive genetic research and its potential implications for future prevention of this often fatal condition are urgently needed, efforts to elucidate the susceptibility loci of IAs are hindered by the issues bewildering the most common and complex genetic disorders, such as low penetrance, late onset, and uncertain modes of inheritance. These efforts are further complicated by the fact that many IA lesions remain asymptomatic or go undiagnosed. In this review, we present and discuss the current status of genetic studies of IAs and we recommend comprehensive genome-wide association studies to identify genetic loci that underlie this complex disease.

Familial intracranial aneurysms

OBJECTIVE

Numerous studies have compared the characteristics of familial intracranial aneurysms with those of non-familial aneurysms. To better understand familial subarachnoid hemorrhage (SAH), we studied a series of patients with SAH who had at least one first-degree relative with SAH, and compared our results with those of previous studies.

METHODS

We identified patients treated for SAH at our hospital between January 1993 and October 2006 and analyzed those patients with one or more first-degree relatives with SAH. We retrospectively collected data from patients with a family history and searched for patients who had relatives with aneurysms or who had been treated at other hospitals for SAH.

RESULTS

We identified 12 patients from six families with at least two first-degree relatives with SAH. All patients had affected first-degree relatives; in five families, they were siblings. The mean age at the time of rupture was 49.75 years; in four families, the age difference was within 5 years. In five patients (42%), the aneurysm was located in the middle cerebral artery. Only one patient had an aneurysm in the anterior communicating artery.

CONCLUSION

In agreement with previous studies, our results showed that familial aneurysms, in comparison with non-familiar aneurysms, ruptured at a younger age and smaller size, had a high incidence in the middle cerebral artery, and were underrepresented in the anterior communicating artery. Interestingly, the age at the time of rupture was similar between relatives. Screening should be considered in the fifth or sixth decade for those who have a sibling with SAH.

Risks of subarachnoid hemorrhage in siblings: a nationwide epidemiological study from Sweden

This nationwide study aimed to enhance available data by determining sibling risks of subarachnoid hemorrhage in a total population. The MigMed database at the Karolinska Institute, Stockholm, was used to identify all cases of subarachnoid hemorrhage diagnosed in Sweden between 1987 and 2001. Incidence ratios standardized for age, region, and socioeconomic status (SIRs) were calculated for persons with at least 1 sibling with subarachnoid hemorrhage. The reference group consisted of persons whose siblings had no subarachnoid hemorrhage. A total of 90 affected siblings were identified; their SIR of subarachnoid hemorrhage was 2.75. The risk decreased with increasing age in both men and women. Within the limits of the sample size, no sex differences could be observed. The relatively high sibling risks are likely to be due to heritable causes and shared environmental factors. Genetic causes possibly weigh more in early- than late-onset cases. This study shows the feasibility of carrying out nationwide family studies on subarachnoid hemorrhage.

Association of Kallikrein Gene Polymorphisms With Intracranial Aneurysms

Background and Purpose— Genomewide DNA linkage analysis identified a susceptibility locus for intracranial aneurysm (IA) on chromosome 19q13 in the Finnish population, a region including the kallikrein gene cluster. We investigated the association of single nucleotide polymorphisms (SNPs) in the kallikrein gene cluster with IA in the Finnish population.

Methods— We genotyped 18 haplotype-tagging SNPs spanning a 244 kbp region in the kallikrein gene cluster for 266 Finnish IA cases and 290 Finnish control subjects. In a second phase, we genotyped 2 SNPs (rs1722561 and rs1701946) in an additional set of 102 Finnish IA cases and 102 Finnish control subjects; and in a third phase, we genotyped these 2 SNPs in 156 Russian IA cases and 186 Russian control subjects. Both single-marker and haplotype-based tests of association were performed.

Results— In phase I, SNPs rs1722561 and rs1701946 were significantly associated with IA in the Finnish population for single locus models (rs1722561: P =0.0395; rs1701946: P =0.0253). A 2-SNP haplotype block (rs1722561–rs1701946) identified in phase I was also associated with IA in the expanded Finnish (phase II) data set (asymptotic P =0.012; empirical P =0.019). In the Finnish and Russian combined data set (phase III) with 524 cases and 578 control subjects, the same 2 SNPs (OR: 1.35, 95% CI: 1.14, 1.60; P =0.0005 for rs1722561 and OR: 1.32, 95% CI: 1.12, 1.57; P =0.0011 for rs1701946) were significantly associated with IA. These SNPs are located in the intronic region of KLK8 , although linkage disequilibrium could extend from rs268912–rs2250066, a ≈76-kbp region that includes KLK5–KLK10.

Conclusions— Polymorphisms within the kallikrein gene cluster are associated with IA suggesting that the kallikreins are important candidate genes for IA.

A FORM OF DYSPLASIA OR A FORTUITOUS ASSOCIATION? A CEREBRAL ANEURYSM INSIDE AN ARACHNOID CYST

OBJECTIVE

Although arachnoid cysts and intracranial aneurysms are very common lesions, their association in the same patient is rare. We present a case of a middle cerebral artery aneurysm ruptured into an arachnoid cyst. We found only six cases with intracystic hemorrhage reported in the literature. The presence of an arachnoid cyst can mislead clinical presentation. The patient presented a paradoxically small temporal fossa and thickening of the temporal and sphenoid bone. The authors suggest that this uncommon association (arachnoid cyst, atypical cranial vault, and “mirror-like” cerebral aneurysm) could represent a form of dysplasia.

CLINICAL PRESENTATION

A 46-year-old patient presented with a 3-week history of slight headaches, which had worsened in the last 3 days before presentation. Computed tomographic scans showed a cystic lesion located in the middle cranial fossa and sylvian fissure with suspected aneurysm dilation inside. Magnetic resonance imaging scans showed an intracystic hemorrhage but not subarachnoid hemorrhage. Paradoxically, changes in the cranial vault around the cyst were noted. Digital subtraction angiography showed bilateral “mirror” middle cerebral artery aneurysms.

INTERVENTION

A large right pterional craniotomy was performed with full microsurgical removal of the arachnoid cyst walls and aneurysm clipping. The aneurysm was in the medial wall of the arachnoid cyst with its dome inside the cyst. The contralateral aneurysm was clipped 2 weeks later. The follow-up period was uneventful, and the patient returned to normal life.

CONCLUSION

Rupture of a cerebral aneurysm into an arachnoid cyst is rare. Clinical presentation may be unusual because the cyst can prevent subarachnoid hemorrhage. A middle fossa cranial arachnoid cyst in the presence of temporal bone depression, small middle fossa, and thickness of squamous temporal bone and the lesser wing of sphenoid is rare and suggests that congenital factors may play an important role in their development. The exceptional association between “mirror” aneurysms and arachnoid cyst with bone changes suggests a possible congenital form of dysplasia.

Model-based linkage analyses confirm chromosome 19q13.3 as a susceptibility locus for intracranial aneurysm

BACKGROUND AND PURPOSE

In previous studies of familial intracranial aneurysm (IA), parametric linkage analyses have been undertaken for five unrelated families, four providing maximum logarithm of odds (LOD) scores with dominant models and one with a recessive model. Each family was linked to a distinct locus, indicating locus heterogeneity. This study aimed to examine whether Japanese IA families consistent with autosomal-dominant mode of inheritance support linkage to these loci.

METHODS

We performed genomewide linkage analysis using the GENEHUNTER program. Affected-only parametric linkage analysis was used for 41 affected members in nine unrelated IA families with dominant models, which were selected from 29 families used for a nonparametric (model-free) linkage analysis in our previous study.

RESULTS

We failed to support the linkage to previously reported autosomal-dominant loci. Instead, we found linkage to chromosome 19q13.3 with a maximum multipoint LOD score of 4.10. The LOD-1 interval (regions with LOD scores of >1) was 8.0 cM between D19S198 and D19S902.

CONCLUSIONS

A genomewide scan for IA families with dominant models in Japan confirmed the locus at chromosome 19q13.3, which has also been reported as a candidate locus in a Finnish population.

Genetics Of Intracranial Aneurysms

Despite advances in the treatment of intracranial aneurysms (IA) in recent years, the overall outcome of patients with aneurysmal subarachnoid hemorrhage has shown only modest improvement. Given this poor prognosis, diagnosis of IA before rupture is of paramount importance. Currently, there are no reliable methods other than screening imaging studies of high-risk individuals to diagnose asymptomatic patients. Multiple levels of evidence suggest that environmental factors acting in concert with genetic susceptibilities lead to the formation, growth, and rupture of aneurysms in these patients. Epidemiological studies have already identified aneurysm-specific risk factors such as size and location, as well as patient-specific risk factors, such as age, sex, and presence of medical comorbidities, such as hypertension. In addition, exposure to certain environmental factors such as smoking have been shown to be important in the formation of IA. Furthermore, substantial evidence proves that certain loci contribute genetically to IA pathogenesis. Genome-wide linkage studies using relative pairs or rare families that are affected with the Mendelian forms of IA have already shown genetic heterogeneity of IA, suggesting that multiple genes, alone or in combination, are important in the disease pathophysiology. The linkage results, along with association studies, will ultimately lead to the identification of IA susceptibility genes. Identification of the genes important in IA pathogenesis will not only provide novel insights into the primary determinants of IA, but will also result in new opportunities for early diagnosis in the preclinical setting. Ultimately, novel therapeutic strategies based on biology will be developed, which will target these newly elucidated genetic susceptibilities.

Growth factor receptor expression and remodeling of saccular cerebral artery aneurysm walls: implications for biological therapy preventing rupture

OBJECTIVE

Remodeling of the saccular cerebral artery aneurysm (SCAA) wall, known to be associated with rupture, might be modified with bioactive endovascular implants or systemic drug therapy targeted at growth factor receptors to prevent rupture. The receptors regulating SCAA wall remodeling are, however, unknown.

MATERIALS AND METHODS

Immunostaining for 12 growth factor receptors, and markers for matrix synthesis, proliferation, and inflammatory cell infiltration, were analyzed in 21 unruptured and 35 ruptured aneurysm fundi resected after microsurgical clipping of the aneurysm neck. The results were compared with clinical and radiological data.

RESULTS

Eleven of the 12 receptors studied were expressed at varying intensities in the 56 SCAA walls. Only transforming growth factor (TGF)beta-R2 and vascular endothelial growth factor (VEGF)-R1 were associated with rupture and basic fibroblast growth factor-R1 with minor leaks (P = 0.018). TGFbeta-R3 and VEGF-R1 was associated with wall remodeling (P = 0.043 and 0.027), and VEGF-R1 was associated with T-cell and macrophage infiltration as well as organization of luminal thrombosis (P = 0.019). VEGF-R2 was associated with myointimal hyperplasia (P = 0.017) and proliferation (P < 0.001).

CONCLUSION

VEGF, TGFbeta, and basic fibroblast growth factor receptors were associated with SCAA wall remodeling, making them potential targets for bioactive endovascular implants or drug therapy aiming to reinforce the SCAA wall.

A new locus for autosomal dominant intracranial aneurysm, ANIB4, maps to chromosome 5p15.2-14.3

BACKGROUND

Intracranial aneurysms (IA) are dilatations of intracranial arteries that occur most commonly at arterial bifurcations. Unruptured IA are present in approximately 1-2% of the population aged over 30 years of age. Aneurysms are only rarely symptomatic unless they rupture, which typically results in a subarachnoid haemorrhage associated with high morbidity and mortality.

METHODS

A large French Canadian (FC) family (Aneu60) was identified which contained 12 affected individuals with intracranial aneurysms. Nine of the affected patients and three unaffected individuals were sent for an 8 cM genome-wide scan. Multipoint and two-point methods were used to analyse the scan data by using a dominant parametric model.

RESULTS

We identified an IA susceptibility locus (ANIB4) located on chromosome 5p15.2-14.3. The locus was found by genome-wide linkage analysis and follow up analyses provided a maximum multipoint LOD score of 3.57 over the region. An identical haplotype segment of 7.2 Mb was found in a second FC pedigree and contributes to the refinement of the candidate gene interval.

CONCLUSIONS

Our results indicate that there is a major gene locus on chromosome 5p.

Is there any evidence for linkage on chromosome 17cen in affected Japanese sib-pairs with an intracranial aneurysm?

A linkage region on chromosome 17cen has previously been found in 29 Japanese families with a history of familial intracranial aneurysms (IA). To investigate whether there is evidence of linkage in affected Japanese sib-pairs we performed nonparametric and parametric linkage analysis of a total of 253 familial aneurysm cases including 111 affected sib-pairs (ASP). Ten microsatellite markers covering a 17.7 cM region were chosen, in accordance with previous work in which nominal P had been below 0.05. Statistical analysis was performed by use of Genehunter and Sibpal software. After calculation of the logarithm of the odds (LOD) and nonparametric linkage analysis (NPL) scores our study did not show any linkage in the region analyzed. Our conclusion did not change even after only ASP were analyzed. In contrast with a previous study examining multigenerational Japanese families with IA, most Japanese ASP may not have a genetic linkage to chromosome 17cen.

Outcome of Surgical Clipping of Unruptured Aneurysms as it Compares with a 10-Year Nonclipping Survival Period

OBJECTIVE

Recent studies on the natural history of unruptured intracranial aneurysms dictate that we reevaluate the risks and benefits of surgical intervention as it compares with the natural course. We analyzed the outcome of surgical clipping of a patient cohort with unruptured aneurysms as it compares with a 10 year nonclipping survival period on the basis of two previously published studies (International Study on Unruptured Intracranial Aneurysms and a study by Juvela et al. [36] from Helsinki).

METHODS

Data on 148 unruptured aneurysms in 116 consecutive surgically treated patients were prospectively recorded and retrospectively analyzed. The overall majority were diagnosed with cerebral angiography. Data analyzed included aneurysmal properties and clinical outcomes including surgical related mortalities and morbidities. The observed outcomes were compared with the expected outcome of a 10 year nonclipping survival period if the patient cohort was included in recently reported studies on unruptured aneurysms. More than 1 year follow-up was available in 93.1% (108) of patients and follow-up cerebral angiography was performed in 80% (93) of patients.

RESULTS

Mean age was 53.57 years. There were 25 (16.8%) small aneurysms (less than 7 mm), 70 (47.2%) aneurysms 7 to 12 mm in size, 41 (27.70%) large (13-24 mm), and 12 (8.10%) giant (>25 mm) aneurysms. Posterior circulation aneurysm comprised 13.51%. One hundred forty-three (96.62%) aneurysms were successfully clipped, and 3.37% were either wrapped or later coiled. Surgical-related mortality was 0.82% (1 patient because of air embolism). Surgical related permanent morbidity was 3.44% (4 patients) and transient surgical-related mild morbidities was 7.7% (9 patients). Immediate postsurgical good outcome (Glasgow Outcome Score = 4-5) was 87.93% (102 patients) and 95.68% in 3 months (111 patients). At 1 year, the modified Rankin scale scores were 0 to I = 102, II = 3, III = 2, IV = 1, and V = 0. Residual aneurysms were seen in none of the postoperative angiograms (93 patients). Using the chi method, the comparison of the expected to the observed mortality and morbidity revealed a statistically significant difference in the mortality in favor of surgical clipping (P = 0.034 when compared with the International Study on Unruptured Intracranial Aneurysms and P = 0.05 when compared with the Juvela et al. [36] study). There was no statistically significant difference in the permanent morbidity.

CONCLUSION

Studies on natural history of unruptured intracranial aneurysms suggest 10 year cumulative bleeding-related mortality and severe morbidity of no less than 7.5%. In our study, surgical clipping resulted in an 0.8% rate of mortality and 3.4% permanent morbidity. This suggests that surgical clipping has the potential of a superior outcome to the natural history of patients who have an estimated life expectancy of no less than 10 years.

Healing of Intracranial Aneurysms with Bioactive Coils

Inadequate healing is an important mechanism for aneurysm development and recanalization after embolization. Matrix coils have been shown by experimental studies to enhance vascular repair and fibrosis, thus reducing the risk of recanalization. The clinical application of Matrix coils represents the transition from pure mechanical occlusion to adjunct biologic healing of aneurysms. Our preliminary clinical experience reveals evidence of a healing response in aneurysms treated with Matrix coils. This technology can be further improved through the incorporation of new knowledge on the molecular pathogenesis of aneurysms and the cellular and molecular mechanisms of healing.

The Familial Intracranial Aneurysm (FIA) study protocol

Background

Subarachnoid hemorrhage (SAH) due to ruptured intracranial aneurysms (IAs) occurs in about 20,000 people per year in the U.S. annually and nearly half of the affected persons are dead within the first 30 days. Survivors of ruptured IAs are often left with substantial disability. Thus, primary prevention of aneurysm formation and rupture is of paramount importance. Prior studies indicate that genetic factors are important in the formation and rupture of IAs. The long-term goal of the Familial Intracranial Aneurysm (FIA) Study is to identify genes that underlie the development and rupture of intracranial aneurysms (IA).

Methods/Design

The FIA Study includes 26 clinical centers which have extensive experience in the clinical management and imaging of intracerebral aneurysms. 475 families with affected sib pairs or with multiple affected relatives will be enrolled through retrospective and prospective screening of potential subjects with an IA. After giving informed consent, the proband or their spokesperson invites other family members to participate. Each participant is interviewed using a standardized questionnaire which covers medical history, social history and demographic information. In addition blood is drawn from each participant for DNA isolation and immortalization of lymphocytes. High- risk family members without a previously diagnosed IA undergo magnetic resonance angiography (MRA) to identify asymptomatic unruptured aneurysms. A 10 cM genome screen will be performed to identify FIA susceptibility loci. Due to the significant mortality of affected individuals, novel approaches are employed to reconstruct the genotype of critical deceased individuals. These include the intensive recruitment of the spouse and children of deceased, affected individuals.

Discussion

A successful, adequately-powered genetic linkage study of IA is challenging given the very high, early mortality of ruptured IA. Design features in the FIA Study that address this challenge include recruitment at a large number of highly active clinical centers, comprehensive screening and recruitment techniques, non-invasive vascular imaging of high-risk subjects, genome reconstruction of dead affected individuals using marker data from closely related family members, and inclusion of environmental covariates in the statistical analysis.

The familial risk of subarachnoid haemorrhage

Relatives of people with aneurysmal subarachnoid haemorrhage (SAH) may be at increased risk of SAH, but precise data on the level of risk and which relatives are most likely to be affected are lacking. We studied two samples: 5478 relatives of patients from the whole of Scotland who had a SAH in one year and 3213 relatives of patients with a SAH admitted to the West of Scotland regional neurosurgical unit 10 years previously. Overall, 2% of all relatives in each sample had a SAH. In the Scotland-wide sample, the absolute lifetime risk of SAH (from birth to 70 years) was higher for first-degree relatives [4.7%; 95% confidence interval (CI): 3.1-6.3%] than for second-degree (1.9%; 95% CI: 1.0-2.9%). In the West of Scotland sample, the lifetime risks were very similar to the Scotland-wide sample. The 10-year prospective risk for first-degree relatives alive at the time of the index patient's SAH was 1.2% (95% CI: 0.4-2%) and for second-degree was 0.5% (95% CI: 0.1-0.8%). There was a trend for risk to be highest in families with two first-degree relatives affected and lowest with only one second-degree affected. Most living relatives of patients who suffer a SAH are at low absolute risk of a future haemorrhage; screening is inappropriate except for the few families in whom two or more first-degree relatives, i.e. index case plus one extra have been affected.

Alpha1-antichymotrypsin gene (SERPINA3) A/T polymorphism as a risk factor for aneurysmal subarachnoid hemorrhage

BACKGROUND AND PURPOSE

The member 3 of clade A of serine proteinase inhibitors (SERPINA3), known previously as the alpha1-antichymotrypsin, is an acute phase protein, the levels of which increase in acute and chronic inflammation. The A/T polymorphism of the SERPINA3 gene influences expression of SERPINA3 protein. SERPINA3 can be related to aneurysmal subarachnoid hemorrhage (SAH) by influencing inflammation or by regulating cathepsin G activity. We studied the significance of SERPINA3 A/T polymorphism in patients with aneurysmal SAH compared with healthy controls.

METHODS

A total of 180 patients with aneurysmal SAH and 263 healthy controls were genotyped for the SERPINA3 A/T polymorphism. Aneurysmal SAH was diagnosed by cranial computed tomography or lumbar puncture and digital subtraction angiography. SERPINA3 polymorphism was detected by polymerase chain reaction amplification and restriction enzyme digestion.

RESULTS

The SERPINA3 genotype distribution in patients with aneurysmal SAH (AA-29 16.1%; AT-108 60.0%; TT-43 23.9%) differed significantly from controls (AA-70 26.6%; AT-123 46.8%; TT-70 26.6%; P=0.009). A logistic regression model showed that the presence of genotype with T allele (AT+TT; odds ratio [OR], 2.01; 95% CI, 1.19 to 3.38; P=0.009) or AA genotype (OR, 0.49; 95% CI, 0.30 to 0.84; P=0.009) of the SERPINA3 influences the risk for aneurysmal SAH independently from smoking, excessive alcohol consumption, and hypertension.

CONCLUSIONS

The A/T polymorphism of SERPINA3 gene is associated with the risk factor for aneurysmal SAH.

Genome-wide scan for Japanese familial intracranial aneurysms: linkage to several chromosomal regions

BACKGROUND

Genetic factors have an important role in the pathogenesis of intracranial aneurysm (IA). The results of previous studies have suggested several loci.

METHODS AND RESULTS

From 29 IA families with > or =3 individuals affected by IA, we used nonparametric (model-free) methods for linkage analyses, using GENEHUNTER and Merlin software. Genome-wide linkage analyses revealed 3 regions on chromosomes 17cen (maximum nonparametric logarithm of the odds score [MNS] = 3.00, nominal P=0.001), 19q13 (MNS=2.15, nominal P=0.020), and Xp22 (MNS=2.16, nominal P=0.019). We tested 4 candidate genes in these regions: the microfibril-associated protein 4 gene (MFAP4) and the promoter polymorphism of the inducible nitric oxide synthase gene (NOS2A) on chromosome 17cen, the epsilon genotypes of the apolipoprotein E gene (APOE) on chromosome 19q13, and the angiotensin I converting enzyme 2 gene (ACE2) on chromosome Xp22. Associations of their polymorphisms with IA were evaluated by a case-control study (100 cases: 29 probands from IA families and 71 unrelated subjects with IAs, 100 unrelated control subjects [unaffected members with IAs and absence of family history of IAs]). However, the case-control study showed that none of the polymorphisms of the examined genes had associations with IA.

CONCLUSIONS

A genome-wide scan in 29 Japanese families with a high degree of familial clustering revealed 1 suggestive linkage region on chromosome 17cen and 2 potentially interesting regions on chromosomes 19q13 and Xp22. These regions were consistent with previous findings in various populations.

Remodeling of Saccular Cerebral Artery Aneurysm Wall Is Associated With Rupture

Background and Purpose— The cellular mechanisms of degeneration and repair preceding rupture of the saccular cerebral artery aneurysm wall need to be elucidated for rational design of growth factor or drug-releasing endovascular devices.

Methods— Patient records, preoperative vascular imaging studies, and the snap-frozen fundi resected after microsurgical clipping from 66 aneurysms were studied. Immunostainings for markers of smooth muscle cell (SMC) phenotype, proliferation, and inflammatory cell subtypes and TUNEL reaction were performed.

Results— Unruptured (24) and ruptured (42) aneurysms had similar dimensions (median diameter in unruptured 6 mm; median in ruptured 7 mm; P =0.308). We identified 4 basic types of aneurysm wall that associated with rupture: (1) endothelialized wall with linearly organized SMCs (17/66; 42% ruptured), (2) thickened wall with disorganized SMCs (20/66; 55% ruptured), (3) hypocellular wall with either myointimal hyperplasia or organizing luminal thrombosis (14/66; 64% ruptured), and (4) an extremely thin thrombosis-lined hypocellular wall (15/66; 100% ruptured). Apoptosis, de-endothelialization, luminal thrombosis, SMC proliferation, and T-cell and macrophage infiltration associated with rupture. Furthermore, macrophage infiltration associated with SMC proliferation, and both were increased in ruptured aneurysms resected <12 hours from rupture, suggesting that these were not just reactive changes.

Conclusions— Before rupture, the wall of saccular cerebral artery aneurysm undergoes morphological changes associated with remodeling of the aneurysm wall. Some of these changes, like SMC proliferation and macrophage infiltration, likely reflect ongoing repair attempts that could be enhanced with pharmacological therapy.

Genome-wide linkage in a large Dutch consanguineous family maps a locus for intracranial aneurysms to chromosome 2p13

BACKGROUND AND PURPOSE

Familial occurrence of intracranial aneurysms suggests a genetic factor in the development of these aneurysms. In this study, we present the identification of a susceptibility locus for the development of intracranial aneurysms detected by a genome-wide linkage approach in a large consanguineous pedigree.

METHODS

Patients with clinical signs and symptoms of intracranial aneurysms, confirmed by radiological, surgical, or postmortem investigations, were included in the study. Magnetic resonance angiography was used to detect asymptomatic aneurysms in relatives.

RESULTS

Seven out of 20 siblings had an intracranial aneurysm. Genome-wide multipoint linkage analysis showed a significant logarithm of the odds score of 3.55.

CONCLUSIONS

In a large consanguineous pedigree intracranial aneurysms are linked to chromosome 2p13 in a region between markers D2S2206 and D2S2977.