Cyclo-oxygenase 2, a putative mediator of vessel remodeling, is expressed in the brain AVM vessels and associates with inflammation.

BACKGROUND: Brain arteriovenous malformations (bAVM) may rupture causing disability or death. BAVM vessels are characterized by abnormally high flow that in general triggers expansive vessel remodeling mediated by cyclo-oxygenase-2 (COX2), the target of non-steroidal anti-inflammatory drugs. We investigated whether COX2 is expressed in bAVMs and whether it associates with inflammation and haemorrhage in these lesions. METHODS: Tissue was obtained from surgery of 139 bAVMs and 21 normal Circle of Willis samples. The samples were studied with immunohistochemistry and real-time quantitative polymerase chain reaction (RT-PCR). Clinical data was collected from patient records. RESULTS: COX2 expression was found in 78% (109/139) of the bAVMs and localized to the vessels' lumen or medial layer in 70% (95/135) of the bAVMs. Receptors for prostaglandin E2, a COX2-derived mediator of vascular remodeling, were found in the endothelial and smooth muscle cells and perivascular inflammatory cells of bAVMs. COX2 was expressed by infiltrating inflammatory cells and correlated with the extent of inflammation (r = .231, p = .007, Spearman rank correlation). COX2 expression did not associate with haemorrhage. CONCLUSION: COX2 is induced in bAVMs, and possibly participates in the regulation of vessel wall remodelling and ongoing inflammation. Role of COX2 signalling in the pathobiology and clinical course of bAVMs merits further studies.

Genome-wide association study of sporadic brain arteriovenous malformations.

BACKGROUND: The pathogenesis of sporadic brain arteriovenous malformations (BAVMs) remains unknown, but studies suggest a genetic component. We estimated the heritability of sporadic BAVM and performed a genome-wide association study (GWAS) to investigate association of common single nucleotide polymorphisms (SNPs) with risk of sporadic BAVM in the international, multicentre Genetics of Arteriovenous Malformation (GEN-AVM) consortium. METHODS: The Caucasian discovery cohort included 515 BAVM cases and 1191 controls genotyped using Affymetrix genome-wide SNP arrays. Genotype data were imputed to 1000 Genomes Project data, and well-imputed SNPs (>0.01 minor allele frequency) were analysed for association with BAVM. 57 top BAVM-associated SNPs (51 SNPs with p<10(-05) or p<10(-04) in candidate pathway genes, and 6 candidate BAVM SNPs) were tested in a replication cohort including 608 BAVM cases and 744 controls. RESULTS: The estimated heritability of BAVM was 17.6% (SE 8.9%, age and sex-adjusted p=0.015). None of the SNPs were significantly associated with BAVM in the replication cohort after correction for multiple testing. 6 SNPs had a nominal p<0.1 in the replication cohort and map to introns in EGFEM1P, SP4 and CDKAL1 or near JAG1 and BNC2. Of the 6 candidate SNPs, 2 in ACVRL1 and MMP3 had a nominal p<0.05 in the replication cohort. CONCLUSIONS: We performed the first GWAS of sporadic BAVM in the largest BAVM cohort assembled to date. No GWAS SNPs were replicated, suggesting that common SNPs do not contribute strongly to BAVM susceptibility. However, heritability estimates suggest a modest but significant genetic contribution.

The ACVRL1 c.314-35A>G polymorphism is associated with organ vascular malformations in hereditary hemorrhagic telangiectasia patients with ENG mutations, but not in patients with ACVRL1 mutations.

Hereditary hemorrhagic telangiectasia (HHT) is characterized by vascular malformations (VMs) and caused by mutations in TGFß/BMP9 pathway genes, most commonly ENG or ACVRL1. Patients with HHT have diverse manifestations related to skin and mucosal telangiectases and organ VMs, including arteriovenous malformations (AVM). The clinical heterogeneity of HHT suggests a role for genetic modifiers. We hypothesized that the ACVRL1 c.314-35A>G and ENG c.207G>A polymorphisms, previously associated with sporadic brain AVM, are associated with organ VM in HHT. We genotyped these variants in 716 patients with HHT and evaluated association of genotype with presence of any organ VM, and specifically with brain VM, liver VM and pulmonary AVM, by multivariate logistic regression analyses stratified by HHT mutation. Among all patients with HHT, neither polymorphism was significantly associated with presence of any organ VM; ACVRL1 c.314-35A>G showed a trend toward association with pulmonary AVM (OR = 1.48, P = 0.062). ACVRL1 c.314-35A>G was significantly associated with any VM among patients with HHT with ENG (OR = 2.66, P = 0.022), but not ACVRL1 (OR = 0.79, P = 0.52) mutations. ACVRL1 c.314-35A>G was also associated with pulmonary AVM and liver VM among ENG mutation heterozygotes. There were no significant associations between ENG c.207G>A and any VM phenotype. These results suggest that common polymorphisms in HHT genes other than the mutated gene modulate phenotype severity of HHT disease, specifically presence of organ VM.

Common variants on 9p21.3 are associated with brain arteriovenous malformations with accompanying arterial aneurysms.

OBJECTIVE: To investigate whether previously reported 9p21.3 single nucleotide polymorphisms (SNPs) are associated with risk of brain arteriovenous malformations (BAVM), which often have accompanying arterial aneurysms. Common variants in the 9p21.3 locus have been reported to be associated with multiple cardiovascular phenotypes, including coronary artery disease and intracranial aneurysms (rs10757278 and rs1333040). METHODS: We used data from 338 BAVM cases participating in the University of California, San Francisco (UCSF)-Kaiser Brain AVM Study Project and 504 healthy controls to evaluate genotypes for seven common SNPs (minor allele frequency>0.05) that were imputed using 1000 Genomes Phase 1 European data (R(2)>0.87). Association with BAVM was tested using logistic regression adjusting for age, sex and the top three principal components of ancestry. Subgroup analysis included 205 BAVM cases with aneurysm data: 74 BAVM with aneurysm versus 504 controls and 131 BAVM without aneurysm versus 504 controls. RESULTS: We observed suggestive association with BAVM and rs10757278-G (OR=1.23, 95% CI 0.99 to 1.53, p=0.064) and rs1333040-T (OR=1.27, 95% CI 1.01 to 1.58, p=0.04). For rs10757278-G, the association was stronger in BAVM cases with aneurysm (OR=1.52, 95% CI 1.03 to 2.22, p=0.032) than in BAVM without aneurysm (OR=0.98, 95% CI 0.72 to 1.34, p=0.91). Similar patterns of effects were observed for rs1333040 and for other SNPs in linkage disequilibrium (r(2)>0.8) with rs10757278. CONCLUSIONS: Common 9p21.3 variants showed similar effect sizes for association with BAVM as previously reported for aneurysmal disease. The association with BAVM appears to be explained by known associations with aneurysms, suggesting that BAVM-associated aneurysms share similar vascular pathology mechanisms with other aneurysm types.

Association of cardiovascular risk factors with disease severity in cerebral cavernous malformation type 1 subjects with the common Hispanic mutation.

BACKGROUND: Cerebral cavernous malformations (CCM) are enlarged vascular lesions affecting 0.1-0.5% of the population worldwide and causing hemorrhagic strokes, seizures, and neurological deficits. Familial CCM type 1 (CCM1) is an autosomal dominant disease caused by mutations in the Krev Interaction Trapped 1 (KRIT1/CCM1) gene, and is characterized by multiple brain lesions whose number and size increase with age. The number of lesions varies widely for unknown reasons, even among carriers of similar ages with the same mutation. The purpose of this study was to investigate whether cardiovascular (CV) risk factors influence potential markers of familial CCM1 disease severity, such as lesion count and history of intracerebral hemorrhage. METHODS: We analyzed baseline data from 185 Hispanic subjects, enrolled in the Brain Vascular Malformation Consortium study between June 2010 and March 2013. All subjects were carriers of the founder Q455X 'Common Hispanic Mutation' (CHM) in the KRIT1 gene, and had a clinical diagnosis of CCM or had an affected first- or second-degree relative with CCM. We performed a cross-sectional study, collecting detailed clinical information of CCM1-CHM subjects and cerebral susceptibility-weighted magnetic resonance imaging to assess lesion count. Linear or logistic regression analysis of log-lesion count or history of intracerebral hemorrhage and CV risk factors (age, gender, obesity, diabetes, hypertension, hyperlipidemia and smoking status) and related quantitative traits (body mass index, glycosylated hemoglobin levels, blood pressure, lipids levels and pack-years of cigarette smoking) was performed accommodating familial clustering. RESULTS: CCM1-CHM subjects were mainly female (63.8%) and symptomatic at presentation (63.2%). Lesion count was highly variable (mean ± SD: 57.7 ± 110.6; range: 0-713); 90% of CCM1-CHM subjects had multiple lesions at enrollment. Age (p < 0.001) was positively correlated with lesion count and male gender (p = 0.035) was associated with a greater number of lesions. Obesity (p = 0.001) and higher body mass index (p = 0.002) were associated with fewer lesions. No association with hypertension was detected, however, systolic blood pressure (p = 0.002) was associated with fewer lesions. No significant association with lesion count was observed for diabetes, hyperlipidemia, smoking status or for related quantitative traits. History of intracerebral hemorrhage was not significantly associated with any CV risk factors, however, we found borderline associations of hemorrhage with obesity (p = 0.062), systolic blood pressure (p = 0.083) and pack-years of cigarette smoking (p = 0.055). After correction for multiple testing, age and obesity remained significantly associated with lesion count in CCM1-CHM subjects. CONCLUSIONS: These results suggest that several CV risk factors explain some of the variability in lesion count in Hispanic CCM1-CHM subjects. Although age, gender, obesity, body mass index and systolic blood pressure may influence familial CCM1 disease severity, further longitudinal studies in larger sample sizes are essential to confirm these findings.

Polymorphisms in inflammatory and immune response genes associated with cerebral cavernous malformation type 1 severity.

BACKGROUND: Familial cerebral cavernous malformation type 1 (CCM1) is an autosomal dominant disease caused by mutations in the Krev Interaction Trapped 1 (KRIT1/CCM1) gene, and characterized by multiple brain lesions that often result in intracerebral hemorrhage (ICH), seizures, and neurological deficits. Carriers of the same genetic mutation can present with variable symptoms and severity of disease, suggesting the influence of modifier factors. Evidence is emerging that inflammation and immune response play a role in the pathogenesis of CCM. The purpose of this study was to investigate whether common variants in inflammatory and immune response genes influence the severity of familial CCM1 disease, as manifested by ICH and greater brain lesion count. METHODS: Hispanic CCM1 patients (n=188) harboring the founder Q455X 'common Hispanic mutation' (CHM) in the KRIT1 gene were analyzed at baseline. Participants were enrolled between June 2010 and March 2014 either through the Brain Vascular Malformation Consortium (BVMC) study or through the Angioma Alliance organization. Clinical assessment and cerebral susceptibility-weighted magnetic resonance imaging were performed to determine ICH as well as total and large (≥5 mm in diameter) lesion counts. Samples were genotyped on the Affymetrix Axiom Genome-Wide LAT1 Human Array. We analyzed 830 variants in 56 inflammatory and immune response genes for association with ICH and residuals of log-transformed total or large lesion count adjusted for age at enrollment and gender. Variants were analyzed individually or grouped by sub-pathways or whole pathways. RESULTS: At baseline, 30.3% of CCM1-CHM subjects had ICH, with a mean ± standard deviation (SD) of 60.1±115.0 (range 0-713) for total lesions and 4.9±8.7 (range 0-104) for large lesions. The heritability estimates explained by all autosomal variants were 0.20 (SE=0.31), 0.81 (SE=0.17), and 0.48 (SE=0.19), for ICH, total lesion count, and large lesion count, respectively. TGFBR2 rs9823731 was significantly associated with ICH as well as with the total and large lesion counts (p≤0.017). Further, IL-4 rs9327638, CD14 rs778588, IL-6R rs114660934 and MSR1 rs62489577 were associated with two markers of disease severity. Finally, the whole pathway was associated with total lesion count (p=0.005) with TLR-4 rs10759930, CD14 rs778588, IL-6R rs114660934 and IGH rs57767447 mainly bearing this association. Eicosanoid signaling, extracellular pattern recognition, and immune response sub-pathways were also associated with the total lesion count. CONCLUSIONS: These results suggest that polymorphisms in inflammatory and immune response pathways contribute to variability in CCM1 disease severity and might be used as predictors of disease severity. In particular, TGFBR2 rs9823731 was associated with all three markers of CCM1 disease severity tested, suggesting that TGFBR2 might be a key participant in the mechanism underlying CCM1 disease severity and phenotype variability. However, further longitudinal studies in larger sample sizes are needed to confirm these findings.

Mitochondrial DNA sequence variation is associated with free-living activity energy expenditure in the elderly.

The decline in activity energy expenditure underlies a range of age-associated pathological conditions, neuromuscular and neurological impairments, disability, and mortality. The majority (90%) of the energy needs of the human body are met by mitochondrial oxidative phosphorylation (OXPHOS). OXPHOS is dependent on the coordinated expression and interaction of genes encoded in the nuclear and mitochondrial genomes. We examined the role of mitochondrial genomic variation in free-living activity energy expenditure (AEE) and physical activity levels (PAL) by sequencing the entire (~16.5 kilobases) mtDNA from 138 Health, Aging, and Body Composition Study participants. Among the common mtDNA variants, the hypervariable region 2 m.185G>A variant was significantly associated with AEE (p=0.001) and PAL (p=0.0005) after adjustment for multiple comparisons. Several unique nonsynonymous variants were identified in the extremes of AEE with some occurring at highly conserved sites predicted to affect protein structure and function. Of interest is the p.T194M, CytB substitution in the lower extreme of AEE occurring at a residue in the Qi site of complex III. Among participants with low activity levels, the burden of singleton variants was 30% higher across the entire mtDNA and OXPHOS complex I when compared to those having moderate to high activity levels. A significant pooled variant association across the hypervariable 2 region was observed for AEE and PAL. These results suggest that mtDNA variation is associated with free-living AEE in older persons and may generate new hypotheses by which specific mtDNA complexes, genes, and variants may contribute to the maintenance of activity levels in late life.

Brain-derived neurotrophic factor Val66Met polymorphism predicts worse functional outcome after surgery in patients with unruptured brain arteriovenous malformation.

BACKGROUND AND PURPOSE: The Val66Met polymorphism of brain-derived neurotrophic factor is associated with decreased brain-derived neurotrophic factor secretion and poor outcome after acute neurological injury. We hypothesized that the Met allele is associated with worsening of functional outcome after brain arteriovenous malformation resection. METHODS: Three hundred forty-one surgically treated patients with brain arteriovenous malformation with outcome data were genotyped for Val66Met. Outcome was change in modified Rankin Scale preoperatively versus postoperatively, dichotomized into poor (change >0) or good outcome (change ≤0). Likelihood ratio tests for interactions and logistic regression analysis were performed. RESULTS: A significant interaction (P=0.03) of Val66Met genotype and hemorrhagic presentation existed; thus, ruptured and unruptured patients were considered separately. The Met allele was associated with increased risk of poor outcome among patients presenting unruptured (OR, 2.15; 95% CI, 1.02-4.55; P=0.045) but not ruptured (OR, 0.54; 95% CI, 0.19-1.53; P=0.25), adjusting for covariates. CONCLUSIONS: The Val66Met polymorphism is associated with worsened surgical outcome in patients with unruptured brain arteriovenous malformation, a group that currently has no good risk predictors. Further studies replicating these findings are needed.

Brain arteriovenous malformation multiplicity predicts the diagnosis of hereditary hemorrhagic telangiectasia: quantitative assessment.

BACKGROUND AND PURPOSE: The purpose of this study was to quantitatively estimate the relationship between multiplicity of brain arteriovenous malformations (bAVMs) and the diagnosis of hereditary hemorrhagic telangiectasia (HHT). METHODS: We combined databases from 2 large North American bAVM referral centers, including demographics, clinical presentation, and angiographic characteristics, and compared patients with HHT with non-HHT patients. Logistic regression analysis was performed to quantify the association between bAVM multiplicity and odds of HHT diagnosis. Sensitivity, specificity, positive and negative predictive value, and positive and negative likelihood ratios were calculated to determine accuracy of bAVM multiplicity for screening HHT. RESULTS: Prevalence of HHT was 2.8% in the combined group. bAVM multiplicity was present in 39% of patients with HHT and was highly associated with diagnosis of HHT in univariate (OR, 83; 95% CI, 40-173; P<0.0001) and multivariable (OR, 86; 95% CI, 38-195; P<0.001) models adjusting for age at presentation (P=0.013), symptomatic presentation (P=0.029), and cohort site (P=0.021). bAVM multiplicity alone was associated with high specificity (99.2%; 95% CI, 98.7%-99.6%) and negative predictive value (98.3%; 95% CI, 97.6%-98.8%) and low sensitivity (39.3%; 95% CI, 26.5%-53.2%) and positive predictive value (59.5%; 95% CI, 42.1%-75.2%). Positive and negative likelihood ratio was 51 and 0.61, respectively, for diagnosis of HHT. HHT bAVMs were also more often smaller in size (<3 cm), noneloquent in location, and associated with superficial venous drainage compared with non-HHT bAVMs. CONCLUSIONS: Multiplicity of bAVMs is highly predictive of the diagnosis of HHT. The presence of multiple bAVMs should alert the clinician to the high probability of HHT and lead to comprehensive investigation for this diagnosis.

Admixture mapping of 15,280 African Americans identifies obesity susceptibility loci on chromosomes 5 and X.

The prevalence of obesity (body mass index (BMI) > or =30 kg/m(2)) is higher in African Americans than in European Americans, even after adjustment for socioeconomic factors, suggesting that genetic factors may explain some of the difference. To identify genetic loci influencing BMI, we carried out a pooled analysis of genome-wide admixture mapping scans in 15,280 African Americans from 14 epidemiologic studies. Samples were genotyped at a median of 1,411 ancestry-informative markers. After adjusting for age, sex, and study, BMI was analyzed both as a dichotomized (top 20% versus bottom 20%) and a continuous trait. We found that a higher percentage of European ancestry was significantly correlated with lower BMI (rho = -0.042, P = 1.6x10(-7)). In the dichotomized analysis, we detected two loci on chromosome X as associated with increased African ancestry: the first at Xq25 (locus-specific LOD = 5.94; genome-wide score = 3.22; case-control Z = -3.94); and the second at Xq13.1 (locus-specific LOD = 2.22; case-control Z = -4.62). Quantitative analysis identified a third locus at 5q13.3 where higher BMI was highly significantly associated with greater European ancestry (locus-specific LOD = 6.27; genome-wide score = 3.46). Further mapping studies with dense sets of markers will be necessary to identify the alleles in these regions of chromosomes X and 5 that may be associated with variation in BMI.

Somatic mosaicism in the MAPK pathway in sporadic brain arteriovenous malformation and association with phenotype.

OBJECTIVE: Sporadic brain arteriovenous malformation (BAVM) is a tangled vascular lesion characterized by direct artery-to-vein connections that can cause life-threatening intracerebral hemorrhage (ICH). Recently, somatic mutations in KRAS have been reported in sporadic BAVM, and mutations in other mitogen-activated protein kinase (MAPK) signaling pathway genes have been identified in other vascular malformations. The objectives of this study were to systematically evaluate somatic mutations in MAPK pathway genes in patients with sporadic BAVM lesions and to evaluate the association of somatic mutations with phenotypes of sporadic BAVM severity. METHODS: The authors performed whole-exome sequencing on paired lesion and blood DNA samples from 14 patients with sporadic BAVM, and 295 genes in the MAPK signaling pathway were evaluated to identify genes with somatic mutations in multiple patients with BAVM. Digital droplet polymerase chain reaction was used to validate KRAS G12V and G12D mutations and to assay an additional 56 BAVM samples. RESULTS: The authors identified a total of 24 candidate BAVM-associated somatic variants in 11 MAPK pathway genes. The previously identified KRAS G12V and G12D mutations were the only recurrent mutations. Overall, somatic KRAS G12V was present in 14.5% of BAVM lesions and G12D was present in 31.9%. The authors did not detect a significant association between the presence or allelic burden of KRAS mutation and three BAVM phenotypes: lesion size (maximum diameter), age at diagnosis, and age at ICH. CONCLUSIONS: The authors confirmed the high prevalence of somatic KRAS mutations in sporadic BAVM lesions and identified several candidate somatic variants in other MAPK pathway genes. These somatic variants may contribute to understanding of the etiology of sporadic BAVM and the clinical characteristics of patients with this condition.

Reduced expression of integrin alphavbeta8 is associated with brain arteriovenous malformation pathogenesis.

Brain arteriovenous malformations (BAVMs) are a rare but potentially devastating hemorrhagic disease. Transforming growth factor-beta signaling is required for proper vessel development, and defective transforming growth factor-beta superfamily signaling has been implicated in BAVM pathogenesis. We hypothesized that expression of the transforming growth factor-beta activating integrin, alphavbeta8, is reduced in BAVMs and that decreased beta8 expression leads to defective neoangiogenesis. We determined that beta8 protein expression in perivascular astrocytes was reduced in human BAVM lesional tissue compared with controls and that the angiogenic response to focal vascular endothelial growth factor stimulation in adult mouse brains with local Cre-mediated deletion of itgb8 and smad4 led to vascular dysplasia in newly formed blood vessels. In addition, common genetic variants in ITGB8 were associated with BAVM susceptibility, and ITGB8 genotypes associated with increased risk of BAVMs correlated with decreased beta8 immunostaining in BAVM tissue. These three lines of evidence from human studies and a mouse model suggest that reduced expression of integrin beta8 may be involved in the pathogenesis of sporadic BAVMs.

Angiopoietin-like 4 (ANGPTL4) gene polymorphisms and risk of brain arteriovenous malformations.

BACKGROUND: Brain arteriovenous malformations (BAVM) are high-flow vascular lesions prone to intracranial hemorrhage (ICH). Abnormal angiogenesis is a key characteristic of BAVM tissue. Angiopoietin-like 4 (ANGPTL4), a secreted glycoprotein, is thought to be involved in angiogenesis and required for proper postnatal blood vessel partitioning. We investigated whether common single nucleotide polymorphisms (SNPs) in ANGPTL4 were associated with risk of BAVM or ICH. METHODS AND RESULTS: We conducted a case-control study of 216 Caucasian BAVM cases and 246 healthy controls, and a secondary case-only analysis, comparing 83 ruptured (ICH) with 133 unruptured BAVM cases at presentation. Four tagSNPs in ANGPTL4 captured variation over a 10-kb region (rs2278236, rs1044250, rs11672433, and rs1808536) and were tested for association with BAVM or ICH. The minor allele (A) of rs11672433 (exon 6, Pro389Pro) was associated with an increased risk of BAVM (p = 0.006), which persisted after adjusting for multiple comparisons (p = 0.03). After adjustments for age and sex, carriers of the minor allele (A) remained at higher risk for BAVM compared to noncarriers (odds ratio, OR = 1.56; 95% confidence interval, CI = 1.01-2.41; p = 0.046) and risk of BAVM was increased with increasing copy of the minor A allele (OR = 1.49, 95% CI = 1.03-2.15; p(trend) = 0.03). Five common haplotypes (frequency >1%) were inferred; overall haplotype distribution differed between BAVM cases and controls (χ(2) = 12.2, d.f. = 4, p = 0.02). Neither SNPs (p > 0.05) nor haplotype distribution (χ(2) = 1.1, d.f. = 4, p = 0.89) were associated with risk of ICH among BAVM cases. CONCLUSION: A synonymous SNP in ANGPTL4 and haplotypes carrying it are associated with risk of BAVM but not with ICH presentation in BAVM cases.

GWAS for discovery and replication of genetic loci associated with sudden cardiac arrest in patients with coronary artery disease.

BACKGROUND: Epidemiologic evidence suggests a heritable component to risk for sudden cardiac arrest independent of risk for myocardial infarction. Recent candidate gene association studies for community sudden cardiac arrests have focused on a limited number of biological pathways and yielded conflicting results. We sought to identify novel gene associations for sudden cardiac arrest in patients with coronary artery disease by performing a genome-wide association study. METHODS: Tagging SNPs (n = 338,328) spanning the genome were typed in a case-control study comparing 89 patients with coronary artery disease and sudden cardiac arrest due to ventricular tachycardia or ventricular fibrillation to 520 healthy controls. RESULTS: Fourteen SNPs including 7 SNPs among 7 genes (ACYP2, AP1G2, ESR1, DGES2, GRIA1, KCTD1, ZNF385B) were associated with sudden cardiac arrest (all p < 1.30 × 10(-7)), following Bonferroni correction and adjustment for population substructure, age, and sex; genetic variation in ESR1 (p = 2.62 × 10(-8); Odds Ratio [OR] = 1.43, 95% confidence interval [CI]:1.277, 1.596) has previously been established as a risk factor for cardiovascular disease. In tandem, the role of 9 genes for monogenic long QT syndrome (LQT1-9) was assessed, yielding evidence of association with CACNA1C (LQT8; p = 3.09 × 10(-4); OR = 1.18, 95% CI:1.079, 1.290). We also assessed 4 recently published gene associations for sudden cardiac arrest, validating NOS1AP (p = 4.50 × 10(-2), OR = 1.15, 95% CI:1.003, 1.326), CSMD2 (p = 6.6 × 10(-3), OR = 2.27, 95% CI:1.681, 2.859), and AGTR1 (p = 3.00 × 10(-3), OR = 1.13, 95% CI:1.042, 1.215). CONCLUSION: We demonstrate 11 gene associations for sudden cardiac arrest due to ventricular tachycardia/ventricular fibrillation in patients with coronary artery disease. Validation studies in independent cohorts and functional studies are required to confirm these associations.

Brain arteriovenous malformation pathogenesis: a response-to-injury paradigm.

Brain arteriovenous malformations (AVMs) are a rare but important cause of intracranial hemorrhage (ICH) in young adults. In this paper, we review both human and animal studies of brain AVM, focusing on the: (1) natural history of AVM hemorrhage, (2) genetic and expression studies of AVM susceptibility and hemorrhage, and (3) strategies for development of a brain AVM model in adult mice. These data target various mechanisms that must act in concert to regulate normal angiogenic response to injury. Based on the various lines of evidence reviewed in this paper, we propose a "response-to-injury" model of brain AVM pathogenesis.

Assessing the association of common genetic variants in EPHB4 and RASA1 with phenotype severity in familial cerebral cavernous malformation.

BACKGROUND: To investigate whether common variants in EPHB4 and RASA1 are associated with cerebral cavernous malformation (CCM) disease severity phenotypes, including intracranial hemorrhage (ICH), total and large lesion counts. METHODS: Familial CCM cases enrolled in the Brain Vascular Malformation Consortium were included (n = 338). Total lesions and large lesions (≥5 mm) were counted on MRI; clinical history of ICH at enrollment was assessed by medical records. Samples were genotyped on the Affymetrix Axiom Genome-Wide LAT1 Human Array. We tested the association of seven common variants (three in EPHB4 and four in RASA1) using multivariable logistic regression for ICH (odds ratio, OR) and multivariable linear regression for total and large lesion counts (proportional increase, PI), adjusting for age, sex, and three principal components. Significance was based on Bonferroni adjustment for multiple comparisons (0.05/7 variants = 0.007). RESULTS: EPHB4 variants were not significantly associated with CCM severity phenotypes. One RASA1 intronic variant (rs72783711 A>C) was significantly associated with ICH (OR = 1.82, 95% CI = 1.21-2.37, p = 0.004) and nominally associated with large lesion count (PI = 1.17, 95% CI = 1.03-1.32, p = 0.02). CONCLUSION: A common RASA1 variant may be associated with ICH and large lesion count in familial CCM. EPHB4 variants were not associated with any of the three CCM severity phenotypes.

Seizure Incidence Rates in Children and Adults With Familial Cerebral Cavernous Malformations.

BACKGROUND AND OBJECTIVES: Seizure incidence rates related to Familial Cerebral Cavernous Malformation (FCCM) are not well described, especially for children. To measure the seizure incidence rate, examine seizure predictors and characterize epilepsy severity, we studied a cohort of children and adults with FCCM enrolled in the Brain Vascular Malformation Consortium (BVMC). METHODS: Seizure data were collected from participants with FCCM in the BVMC at enrollment and during follow-up. We estimated seizure probability by age, and tested whether cerebral cavernous malformation (CCM) counts or genotype were associated with earlier seizure onset. RESULTS: The study cohort included 479 FCCM cases. Median age at enrollment was 42.5 years (Interquartile Range [IQR] 22.5-55.0) and 19% were children (<18 years old). Median large CCM count was 3 (IQR: 1-5). Among 393 with genotyping, mutations were: CCM1-Common Hispanic Mutations (88%), another CCM1 mutation (5%), CCM2 mutations (5%), and CCM3 mutations (2%). Prior to or during the study, 202 (42%) had a seizure. The cumulative incidence of a childhood seizure was 20.3% (95% CI 17.0 - 23.4) and by age 80 years was 60.4% (95% CI 54.2-65.7). More total CCMs (Hazard Ratio [HR] 1.24 per SD unit increase, 95% CI 1.1 - 1.4) or more large CCMs (HR=1.5 per SD unit increase, 95% CI 1.2-1.9) than expected for age and sex increased seizure risk. A CCM3 mutation also increased risk compared to other mutations (HR 3.11, 95% CI 1.15-8.45). Individuals with a seizure prior to enrollment had increased hospitalization rates during follow-up (Incidence Rate Ratio 10.9, 95% CI 2.41 - 49.32) compared to patients without a seizure history. DISCUSSION: Individuals with FCCM have a high seizure incidence, and those with more CCMs or CCM3 genotype are at greater risk. Seizures increase health care utilization in FCCM.

Pilot investigation of circulating angiogenic and inflammatory biomarkers associated with vascular malformations.

BACKGROUND: Vascular malformations in the central nervous system are difficult to monitor and treat due to their inaccessible location. Angiogenic and inflammatory proteins are secreted into the bloodstream and may serve as useful biomarkers for identifying patients at risk for complications or with certain disease phenotypes. METHODS: A validated multiplex protein array consisting of 26 angiogenic and inflammatory biomarkers (Angiome) was assessed in plasma isolated from healthy controls and patients with either sporadic brain arteriovenous malformation (BAVM), familial cerebral cavernous malformation (CCM), or hereditary hemorrhagic telangiectasia (HHT). These samples were obtained from archives of ongoing research studies at the University of California San Francisco and through prospective collection at the Toronto HHT Centre at St. Michael's Hospital. RESULTS: We compared circulating biomarker levels from each patient group to healthy controls and analyzed each pairwise combination of patient groups for differences in biomarker levels. Additionally, we analyzed the HHT samples to determine the association between biomarker levels and the following HHT-specific phenotypes, BAVM, pulmonary arteriovenous malformation (PAVM), liver vascular malformation (LVM), and gastrointestinal (GI) bleeding. Compared to controls, levels of SDF1 were significantly elevated in HHT patients (Proportional Increase [PI] = 1.87, p < 0.001, q = 0.011). Levels of sENG were significantly reduced in HHT patients compared to controls (PI = 0.56, p < 0.001, q < 0.001), reflecting the prevalence of HHT1 patients in this cohort. Levels of IL6 (PI = 3.22, p < 0.001, q < 0.001) and sTGFßR3 (PI = 0.70, p = 0.001, q < 0.029) differed significantly in CCM patients compared to controls. Compared to controls, ten of the biomarkers were significantly different in sporadic BAVM patients (q-values < 0.05). Among the pairwise combinations of patient groups, a significant elevation was observed in TGFß1 in CCM patients compared to sporadic BAVM patients (PI = 2.30, p < 0.001, q = 0.034). When examining the association of circulating biomarker levels with HHT-specific phenotypes, four markers were significantly lower in HHT patients with BAVM (q-values < 0.05), and four markers were significantly higher in patients with LVM (q-values < 0.05). CONCLUSIONS: This pilot study suggests that the profile of circulating angiogenic and inflammatory biomarkers may be unique to each type of vascular malformation. Furthermore, this study indicates that circulating biomarkers may be useful for assessing phenotypic traits of vascular malformations.

Differences in presentation and progression between severe FIC1 and BSEP deficiencies.

BACKGROUND & AIMS: Progressive familial intrahepatic cholestasis (PFIC) with normal serum levels of gamma-glutamyltranspeptidase can result from mutations in ATP8B1 (encoding familial intrahepatic cholestasis 1 [FIC1]) or ABCB11 (encoding bile salt export pump [BSEP]). We evaluated clinical and laboratory features of disease in patients diagnosed with PFIC, who carried mutations in ATP8B1 (FIC1 deficiency) or ABCB11 (BSEP deficiency). Our goal was to identify features that distinguish presentation and course of these two disorders, thus facilitating diagnosis and elucidating the differing consequences of ATP8B1 and ABCB11 mutations. METHODS: A retrospective multi-center study was conducted, using questionnaires and chart review. Available clinical and biochemical data from 145 PFIC patients with mutations in either ATP8B1 (61 "FIC1 patients") or ABCB11 (84 "BSEP patients") were evaluated. RESULTS: At presentation, serum aminotransferase and bile salt levels were higher in BSEP patients; serum alkaline phosphatase values were higher, and serum albumin values were lower, in FIC1 patients. Elevated white blood cell counts, and giant or multinucleate cells at liver biopsy, were more common in BSEP patients. BSEP patients more often had gallstones and portal hypertension. Diarrhea, pancreatic disease, rickets, pneumonia, abnormal sweat tests, hearing impairment, and poor growth were more common in FIC1 patients. Among BSEP patients, the course of disease was less rapidly progressive in patients bearing the D482G mutation. CONCLUSIONS: Severe forms of FIC1 and BSEP deficiency differed. BSEP patients manifested more severe hepatobiliary disease, while FIC1 patients showed greater evidence of extrahepatic disease.

Brain arteriovenous malformation biology relevant to hemorrhage and implication for therapeutic development.

Brain arteriovenous malformations cause intracranial hemorrhage. Molecular characterization of lesional tissue implicates angiogenic (vascular endothelial growth factor, ANG-2, matrix metalloproteinase-9) and inflammatory (cytokines and chemokines) pathways, but the pathogenesis remain obscure and medical therapy is lacking. Macrophage and neutrophil invasion has also been observed in the absence of prior intracranial hemorrhage. Common polymorphisms in interleukin-1beta and activin receptor-like kinase-1 are associated with arteriovenous malformation susceptibility, and polymorphisms in interleukin-1beta, interleukin-6, tumor necrosis factor-alpha and APOE are associated with arteriovenous malformation rupture. These observations suggest that even without a complete understanding of the determinants of arteriovenous malformation development, the recent discoveries of downstream derangements in vascular function and integrity may offer potential targets for therapy development. Furthermore, biomarkers can be established for assessing intracranial hemorrhage risk. Finally, these data will aid in development of model systems for mechanistic testing by development of surrogate phenotypes (microvascular dysplasia) and/or models recapitulating the clinical syndrome of recurrent spontaneous intracranial hemorrhage.