Rare RNF213 variants in the C-terminal region encompassing the RING-finger domain are associated with moyamoya angiopathy in Caucasians

Association of Genetic Variants with Postoperative Donor Artery Development in Moyamoya Disease: RNF213 and Other Moyamoya Angiopathy-Related Gene Analysis

Robust postoperative bypass development is a characteristic of moyamoya disease (MMD); however, genetic factors mediating this phenomenon remain incompletely understood. Therefore, we aimed to elucidate the relationship between postoperative donor artery development and genetic variants. We retrospectively enrolled 63 patients (79 hemispheres) who underwent combined revascularization surgery. Postoperative development of the superficial temporal artery (STA), middle meningeal artery, and deep temporal artery (DTA) was assessed using the caliber-change ratio determined from magnetic resonance angiography measurements. We analyzed RNF213 and 36 other moyamoya angiopathy-related genes by whole-exome sequencing and extracted rare or damaging variants. Thirty-five participants carried RNF213 p.Arg4810Lys (all heterozygotes), whereas 5 had RNF213 rare variants (RVs). p.Arg4810Lys was significantly associated with postoperative DTA development, while age at surgery, hypertension, and hyperlipidemia were inversely associated. Multiple regression analysis revealed that age and p.Arg4810Lys held statistical significance (P = 0.044, coefficient - 0.015, 95% confidence interval (CI) - 0.029 to 0.000 and P = 0.001, coefficient 0.670, 95% CI 0.269 to 1.072, respectively). Those with RNF213 RV without p.Arg4810Lys exhibited a significant trend toward poor DTA development (P = 0.001). Hypertension demonstrated a significant positive association with STA development, which remained significant even after multiple regression analysis (P = 0.001, coefficient 0.303, 95% CI 0.123 to 0.482). Following Bonferroni correction for multiple comparisons, targeted analyses of RNF213 and 36 moyamoya angiopathy-related genes showed a significant association of only RNF213 p.Arg4810Lys with favorable DTA development (P = 0.001). A comprehensive analysis of RNF213, considering both p.Arg4810Lys and RVs, may provide a clearer prediction of postoperative DTA development.

Peripheral blood GATA2 expression impacts RNF213 mutation penetrance and clinical severity in moyamoya disease

BACKGROUND

The p.R4810K founder mutation in the RNF213 gene confers susceptibility to moyamoya disease (MMD) and non-MMD intracranial artery disease. However, penetrance is incomplete, and the underlying molecular mechanism remains unknown.

METHODS AND RESULTS

Transcriptome analysis of peripheral blood was conducted with nine MMD patients and five unaffected mutation carriers from four familial MMD pedigrees. Bayesian network analysis identified upregulated gene modules associated with lipid metabolism and leucocyte development (including GATA2 and SLC45A3), and epidermal growth factor receptor (EGFR) signalling (UBTD1). It also identified downregulated gene modules related to mitochondrial ribosomal proteins (RPS3A and RPL26), and cytotoxic T cell immunity (GZMA and TRGC1). The GATA2 network was replicated through weighted gene co-expression network analysis and further examined in a case-control study, comprising 43 MMD patients, 16 non-MMD patients, 19 unaffected carriers and 35 healthy controls. GATA2 exhibited a significant linear correlation with SLC45A3 and was significantly higher in MMD patients compared with age-matched and sex-matched unaffected carriers or wild-type controls. Among patients with the p.R4810K mutation, higher GATA2 expression was associated with an earlier age of onset, bilateral involvement and symptomatic disease onset.

CONCLUSIONS

Peripheral blood GATA2 expression was associated with increased penetrance of the RNF213 mutation and more severe clinical manifestations in MMD.

The role of the RING finger protein 213 gene in Moyamoya disease

Moyamoya Disease (MMD) represents a chronic and progressive cerebrovascular disorder characterized by the gradual occlusion of the terminal portions of the bilateral internal carotid arteries and their major branches, accompanied by the formation of abnormal vascular networks at the base of the skull. In adolescents, particularly in pediatric populations, MMD is a significant cause of stroke, posing a severe challenge to human health and imposing a heavy burden on healthcare systems. Ring Finger Protein 213 (RNF213), as the primary susceptibility gene for MMD, plays a crucial regulatory role in the initiation, progression, and prognosis of the disease. Despite extensive research on the role of RNF213 in the pathogenesis of MMD, the underlying molecular mechanisms remain incompletely understood and represent a pressing scientific challenge requiring further exploration. This review aims to synthesize the latest research findings and systematically elucidate the multifaceted roles of RNF213 in MMD, including genetic susceptibility, immune-inflammatory responses, blood-brain barrier(BBB) disruption, and angiogenesis. By integrating these findings, this study seeks to provide new insights and theoretical support for a comprehensive and in-depth understanding of the pathophysiological processes of MMD. This research not only contributes to further unraveling the complex pathogenesis of MMD but also lays a solid theoretical foundation for the development of targeted preventive and therapeutic strategies.

Shigella flexneri evades LPS ubiquitylation through IpaH1.4-mediated degradation of RNF213

Pathogens have evolved diverse strategies to counteract host immunity. Ubiquitylation of lipopolysaccharide (LPS) on cytosol-invading bacteria by the E3 ligase RNF213 creates 'eat me' signals for antibacterial autophagy, but whether and how cytosol-adapted bacteria avoid LPS ubiquitylation remains poorly understood. Here, we show that the enterobacterium Shigella flexneri actively antagonizes LPS ubiquitylation through IpaH1.4, a secreted effector protein with ubiquitin E3 ligase activity. IpaH1.4 binds to RNF213, ubiquitylates it and targets it for proteasomal degradation, thus counteracting host-protective LPS ubiquitylation. To understand how IpaH1.4 recognizes RNF213, we determined the cryogenic electron microscopy structure of the IpaH1.4-RNF213 complex. The specificity of the interaction is achieved through the leucine-rich repeat of IpaH1.4, which binds the RING domain of RNF213 by hijacking the conserved RING interface required for binding to ubiquitin-charged E2 enzymes. IpaH1.4 also targets other E3 ligases involved in inflammation and immunity through binding to the E2-interacting face of their RING domains, including the E3 ligase LUBAC that is required for the synthesis of M1-linked ubiquitin chains on cytosol-invading bacteria downstream of RNF213. We conclude that IpaH1.4 has evolved to antagonize multiple antibacterial and proinflammatory host E3 ligases.

Relationship Between RNF213 p.R4810K and Echocardiographic Findings in Patients with Cerebrovascular Diseases: A Multicenter Prospective Cohort Study

BACKGROUND

RING finger protein 213 (RNF213) p.R4810K is an established risk factor for moyamoya disease and intracranial artery stenosis in East Asian people. Recent evidence suggests its potential association with extracranial cardiovascular diseases, including pulmonary hypertension. We hypothesized that insidious abnormal cardiac functions are detected in RNF213 p.R4810K carriers with cerebrovascular diseases.

METHODS AND RESULTS

We investigated patients registered in the National Cerebral and Cardiovascular Center Genome Registry between May 2017 and August 2021 who underwent echocardiography. All patients had cerebrovascular diseases. Patients with a medical history of chronic heart or pulmonary diseases were excluded. RNF213 p.R4810K was genotyped in all the patients. Of 2089 patients registered in the registry, 71 carriers and 1241 noncarriers were eligible for our analyses. The carriage of RNF213 p.R4810K emerged as a significant predictor for longer right ventricular outflow tract acceleration time in multivariable linear regression analysis (β=8.33 [95% CI, 0.92-15.74]; P=0.028). Additionally, the carriers showed increased odds of having right ventricular outflow tract acceleration time values ≥150 milliseconds (odds ratio, 2.22 [95% CI, 1.18-4.18]; P=0.014) in multivariable logistic regression analysis.

CONCLUSIONS

A longer right ventricular outflow tract acceleration time may reflect an increased pulmonary vascular bed induced by abnormal vascular collateral networks and dilation of capillary vessels in peripheral pulmonary arteries in the preclinical stage of RNF213-related pulmonary hypertension. Thus, the right ventricular outflow tract acceleration time marker in RNF213 p.R4810K carriers suggests a biphasic course from the presymptomatic to symptomatic phase. Furthermore, vascular neurologists should carefully examine multiple organs because RNF213-related vasculopathy covers systemic cardiovascular diseases.

REGISTRATION

URL: https://www.umin.ac.jp; Unique identifier: UMIN000050750.

Advances in moyamoya disease: pathogenesis, diagnosis, and therapeutic interventions

Moyamoya disease (MMD) is a type of cerebrovascular disease characterized by occlusion of the distal end of the internal carotid artery and the formation of collateral blood vessels. Over the past 20 years, the landscape of research on MMD has significantly transformed. In this review, we provide insights into the pathogenesis, diagnosis, and therapeutic interventions in MMD. The development of high-throughput sequencing technology has expanded our understanding of genetic susceptibility, identifying MMD-related genes beyond RNF213, such as ACTA2, DIAPH1, HLA, and others. The genetic susceptibility of MMD to its pathological mechanism was summarized and discussed. Based on the second-hit theory, the influences of inflammation, immunity, and environmental factors on MMD were also appropriately summarized. Despite these advancements, revascularization surgery remains the primary treatment for MMD largely because of the lack of effective in vivo and in vitro models. In this study, 16 imaging diagnostic methods for MMD were summarized. Regarding therapeutic intervention, the influences of drugs, endovascular procedures, and revascularization surgeries on patients with MMD were discussed. Future research on the central MMD vascular abnormalities and peripheral circulating factors will provide a more comprehensive understanding of the pathogenic mechanisms of MMD.

Exploring RNF213 in Ischemic Stroke and Moyamoya Disease: From Cellular Models to Clinical Insights

Advances in stroke genetics have highlighted the critical role of rare genetic variants in cerebrovascular diseases, with RNF213 emerging as a key player in ischemic stroke and Moyamoya disease (MMD). Initially identified as the primary susceptibility gene for MMD, RNF213-notably the p.R4810K variant-has been strongly linked to intracranial artery stenosis (ICAS) and various ischemic stroke subtypes, particularly in East Asian populations. This gene encodes an E3 ubiquitin ligase with diverse roles in angiogenesis, vascular remodeling, lipid metabolism, and cerebral blood flow regulation, yet its exact mechanisms in cerebrovascular pathology remain incompletely understood. This review synthesizes findings from genetic studies, as well as cellular and animal models, to provide a holistic understanding of RNF213's involvement in cerebrovascular diseases. Key mechanisms by which RNF213 variants contribute to disease pathogenesis are explored, alongside discussions on their clinical utility as biomarkers and therapeutic targets. Additionally, we address the gene's implications for disease prediction, risk assessment, and cascade screening. By integrating evidence across disciplines, this review identifies critical knowledge gaps, including the biological pathways underlying RNF213's pathogenicity. These insights lay the groundwork for future research and underscore the potential of RNF213 in driving personalized approaches to cerebrovascular disease management.

Difference in Clinical Phenotype, Mutation Position, and Structural Change of RNF213 Rare Variants Between Pediatric and Adult Japanese Patients with Moyamoya Disease

It is unclear how rare RNF213 variants, other than the p.R4810K founder variant, affect the clinical phenotype or the function of RNF213 in moyamoya disease (MMD). This study included 151 Japanese patients with MMD. After performing targeted resequencing for all coding exons in RNF213, we investigated the clinical phenotype and statistically analyzed the genotype-phenotype correlation. We mapped RNF213 variants on a three-dimensional (3D) model of human RNF213 and analyzed the structural changes due to variants. The RNF213 p.R4810K homozygous variant, p.R4810K heterozygous variant, and wild type were detected in 10 (6.6%), 111 (73.5%), and 30 (19.9%) MMD patients, respectively. In addition, 15 rare variants were detected in 16 (10.6%) patients. In addition to the influence of the p.R4810K homozygous variant, the frequency of cerebral infarction at disease onset was higher in pediatric patients with other rare variants (3/6, 50.0%, P = 0.006) than in those with only the p.R4810K heterozygous variant or with no variants (2/51, 3.9%). Furthermore, on 3D modelling of RNF213, the majority of rare variants found in pediatric patients were located in the E3 module and associated with salt bridge loss, contrary to the results for adult patients. The clinical phenotype of rare RNF213 variants, mapped mutation position, and their predicted structural change differed between pediatric and adult patients with MMD. Rare RNF213 variants, in addition to the founder p.R4810K homozygous variant, can influence MMD clinical phenotypes or structural change which may contribute to the destabilization of RNF213.

RNF213 p.Arg4810Lys Variant Is Associated with Higher Stenosis Progression in Asymptomatic Intracranial Artery Stenosis

Intracranial artery stenosis (ICAS) is a significant contributor to ischemic stroke, with the RNF213 p.Arg4810Lys variant identified as a related genetic factor. We explored the clinical outcomes of the RNF213 genotype in patients with asymptomatic ICAS. Between November 2011 and March 2019, 139 patients with asymptomatic ICAS were enrolled in this study. Genotyping for RNF213 p.Arg4810Lys was performed using Sanger sequencing. A comprehensive analysis was conducted to compare the RNF213 genotype with background characteristics and clinical outcomes such as ipsilateral ischemic cerebrovascular events and stenosis progression. RNF213 p.Arg4810Lys was found in 25% of cases, revealing distinct clinical features between carriers and non-carriers. The incidence of ipsilateral ischemic cerebrovascular events was 4.3% (6/139 cases), and stenosis progression was observed in 13% (18/139 cases) during a mean follow-up period of 58 months. Stenosis progression rates were notably higher in the RNF213 variant group (25.7%; 9/35 cases) than in the RNF213 wild-type group (8.7%; 9/104 cases). Cumulative stenosis progression rate was significantly higher in the RNF213 variant group than in the RNF213 wild-type group (log-rank test, P = 0.0004). Multivariate Cox regression analysis indicated a significant association between the RNF213 p.Arg4810Lys variant and an increased risk of stenosis progression (P = 0.03, odds ratio 3.2; 95% confidence interval, 1.1-9.0). The RNF213 p.Arg4810Lys variant exhibits clinical disparities in asymptomatic ICAS and is notably linked to a heightened risk of stenosis progression. These results suggest a distinct difference in the vascular stenosis mechanism associated with this variant, warranting further investigation into its clinical implications and potential mechanistic insights.

RNF213 in moyamoya disease: Genotype-phenotype association and the underlying mechanism

ABSTRACT

Moyamoya disease (MMD) is a cerebrovascular disorder characterized by a steno-occlusive internal carotid artery and compensatory vascular network formation. Although the precise pathogenic mechanism remains elusive, genetic association studies have identified RNF213 as the principal susceptibility gene for MMD, with the single nucleotide polymorphism p.R4810K recognized as the founder variant predominantly in the Asian populations. Distinct genotype-phenotype correlations are observable in RNF213 -related MMD. The clinical manifestations linked to p.R4810K bear commonalities within Asian cohort, including familial predisposition, earlier age of onset, ischemic episodes, and involvement of the posterior cerebral artery (PCA). However, despite these shared phenotypic characteristics, there is significant heterogeneity in RNF213 -related MMD presentations. This diversity manifests as variations across ethnic groups, inconsistent clinical symptoms and prognosis, and occurrence of other vasculopathies involving RNF213 . This heterogeneity, in conjunction with the observed low disease penetrance of RNF213 mutations, suggests that the presence of these mutations may not be sufficient to cause MMD, underscoring the potential influence of other genetic or environmental factors. Although the current research might not have fully identified these additional contributors, experimental evidence points toward the involvement of RNF213 in angiogenesis, lipid metabolism, and the immune response. Future research is required to unveil the molecular mechanisms and identify the factors that synergize with RNF213 in the pathogenesis of MMD.

CXCL12/CXCR4 pathway as a novel therapeutic target for RNF213-associated pulmonary arterial hypertension

Genetic backgrounds of patients with pulmonary arterial hypertension (PAH) were not fully investigated. A variant of c.14429G > A (p.Arg4810Lys) in the ring finger protein 213 gene (RNF213) was recently identified as a risk allele for poor treatment response and poor clinical prognosis in patients with PAH. However, the molecular mechanisms of the RNF213 p.Arg4810Lys variant in development of PAH are unknown. We investigated the underlying molecular mechanisms of RNF213-associated vasculopathy using an in vivo mouse model. RNF213+/p.Arg4828Lys mice, harboring the heterozygous RNF213 p.Arg4828Lys variant corresponding to the p.Arg4810Lys variant in humans, were created using the CRISPR-Cas9 system to recapitulate the genetic status of PAH patients. RNF213+/p.Arg4828Lys mice had a significant elevation of the right ventricular systolic pressure, hypertrophy of the right ventricle, and increased thickness of the pulmonary arterial medial wall compared with wild-type mice after 3 months of exposure to a hypoxic environment. C-X-C motif chemokine ligand 12 (CXCL12), a C-X-C chemokine receptor type 4 (CXCR4) ligand, was significantly elevated in the lungs of RNF213+/p.Arg4828Lys mice, and PAH was ameliorated by the administration of a CXCR4 antagonist. CXCL12-CXCR4 is an angiogenic chemokine axis, and immunohistochemistry demonstrated an increase in CXCR4 in vimentin-positive spindle-shaped cells in adventitia and interstitial lesions in RNF213+/p.Arg4828Lys mice and lung specimens from severe PAH patients with the RNF213 p.Arg4810Lys variant. We confirmed a cause-and-effect relationship between the RNF213 p.Arg4810Lys variant and PAH via the CXCL12-CXCR4 pathway. The findings in this study suggest that targeting this pathway might be a novel therapeutic strategy for RNF213-associated vasculopathy.

Recognition of phylogenetically diverse pathogens through enzymatically amplified recruitment of RNF213

Innate immunity senses microbial ligands known as pathogen-associated molecular patterns (PAMPs). Except for nucleic acids, PAMPs are exceedingly taxa-specific, thus enabling pattern recognition receptors to detect cognate pathogens while ignoring others. How the E3 ubiquitin ligase RNF213 can respond to phylogenetically distant pathogens, including Gram-negative Salmonella, Gram-positive Listeria, and eukaryotic Toxoplasma, remains unknown. Here we report that the evolutionary history of RNF213 is indicative of repeated adaptation to diverse pathogen target structures, especially in and around its newly identified CBM20 carbohydrate-binding domain, which we have resolved by cryo-EM. We find that RNF213 forms coats on phylogenetically distant pathogens. ATP hydrolysis by RNF213's dynein-like domain is essential for coat formation on all three pathogens studied as is RZ finger-mediated E3 ligase activity for bacteria. Coat formation is not diffusion-limited but instead relies on rate-limiting initiation events and subsequent cooperative incorporation of further RNF213 molecules. We conclude that RNF213 responds to evolutionarily distant pathogens through enzymatically amplified cooperative recruitment.

Association between idiopathic hypersomnia and a genetic variant in the PER3 gene

We aim to identify genetic markers associated with idiopathic hypersomnia, a disabling orphan central nervous system disorder of hypersomnolence that is still poorly understood. In our study, DNA was extracted from 79 unrelated patients diagnosed with idiopathic hypersomnia with long sleep time at the National Reference Center for Narcolepsy-France according to very stringent diagnostic criteria. Whole exome sequencing on the first 30 patients with idiopathic hypersomnia (25 females and 5 males) allowed the single nucleotide variants to be compared with a control population of 574 healthy subjects from the French Exome project database. We focused on the identification of genetic variants among 182 genes related to the regulation of sleep and circadian rhythm. Candidate variants obtained by exome sequencing analysis were then validated in a second sample of 49 patients with idiopathic hypersomnia (37 females and 12 males). Our study characterised seven variants from six genes significantly associated with idiopathic hypersomnia compared with controls. A targeted sequencing analysis of these seven variants on 49 other patients with idiopathic hypersomnia confirmed the relative over-representation of the A➔C variant of rs2859390, located in a potential splicing-site of PER3 gene. Our findings support a genetic predisposition and identify pathways involved in the pathogeny of idiopathic hypersomnia. A variant of the PER3 gene may predispose to idiopathic hypersomnia with long sleep time.

Insights into the regulatory role of epigenetics in moyamoya disease: Current advances and future prospectives

Moyamoya disease (MMD) is a progressive steno-occlusive cerebrovascular disorder that predominantly affecting East Asian populations. The intricate interplay of distinct and overlapping mechanisms, including genetic associations such as the RNF213-p.R4810K variant, contributes to the steno-occlusive lesions and moyamoya vessels. However, genetic mutations alone do not fully elucidate the occurrence of MMD, suggesting a potential role for epigenetic factors. Accruing evidence has unveiled the regulatory role of epigenetic markers, including DNA methylation, histone modifications, and non-coding RNAs (ncRNAs), in regulating pivotal cellular and molecular processes implicated in the pathogenesis of MMD by modulating endothelial cells and smooth muscle cells. The profile of these epigenetic markers in cerebral vasculatures and circulation has been determined to identify potential diagnostic biomarkers and therapeutic targets. Furthermore, in vitro studies have demonstrated the multifaceted effects of modulating specific epigenetic markers on MMD pathogenesis. These findings hold great potential for the discovery of novel therapeutic targets, translational studies, and clinical applications. In this review, we comprehensively summarize the current understanding of epigenetic mechanisms, including DNA methylation, histone modifications, and ncRNAs, in the context of MMD. Furthermore, we discuss the potential challenges and opportunities that lie ahead in this rapidly evolving field.

RNF213 p.Arg4810Lys Wild Type is Associated with De Novo Hemorrhage in Asymptomatic Hemispheres with Moyamoya Disease

Clinical implications of RNF213 genetic variants, other than p.Arg4810Lys, in moyamoya disease (MMD), remain unclear. This study aimed to investigate the association of RNF213 variants with clinical phenotypes in MMD. This retrospective cohort study collected data regarding the clinical characteristics of 139 patients with MMD and evaluated the angioarchitectures of 253 hemispheres using digital subtraction angiography at diagnosis. All RNF213 exons were sequenced, and the associations of clinical characteristics and angiographical findings with p.Arg4810Lys, p.Ala4399Thr, and other rare variants (RVs) were examined. Among 139 patients, 100 (71.9%) had p.Arg4810Lys heterozygote (GA) and 39 (28.1%) had the wild type (GG). Fourteen RVs were identified and detetcted in 15/139 (10.8%) patients, and p.Ala4399Thr was detected in 17/139 (12.2%) patients. Hemispheres with GG and p.Ala4399Thr presented with significantly less ischemic events and more hemorrhagic events at diagnosis (p = 0.001 and p = 0.028, respectively). In asymptomatic hemispheres, those with GG were more susceptible to de novo hemorrhage than those with GA (adjusted hazard ratio [aHR] 5.36) with an increased risk when accompanied by p.Ala4399Thr or RVs (aHR 15.22 and 16.60, respectively). Within the choroidal anastomosis-positive hemispheres, GG exhibited a higher incidence of de novo hemorrhage than GA (p = 0.004). The GG of p. Arg4810Lys was a risk factor for de novo hemorrhage in asymptomatic MMD hemispheres. This risk increased with certain other variants and is observed in choroidal anastomosis-positive hemispheres. A comprehensive evaluation of RNF213 variants and angioarchitectures is essential for predicting the phenotype of asymptomatic hemispheres in MMD.

Risk Factors for Preoperative Cerebral Infarction in Infants with Moyamoya Disease

There have been few reports on the risk factors for preoperative cerebral infarction in childhood moyamoya disease (MMD) in infants under 4 years. The aim of this retrospective study is to identify clinical and radiological risk factors for preoperative cerebral infarction in infants under 4 years old with MMD, and the optimal timing for EDAS was also considered. We retrospectively analyzed the risk factors for preoperative cerebral infarction, confirmed by magnetic resonance angiography (MRA), in pediatric patients aged ˂4 years who underwent encephaloduroarteriosynangiosis between April 2005 and July 2022. The clinical and radiological outcomes were determined by two independent reviewers. In addition, potential risk factors for preoperative cerebral infarction, including infarctions at diagnosis and while awaiting surgery, were analyzed using a univariate model and multivariate logistic regression to identify independent predictors of preoperative cerebral infarction. A total of 160 hemispheres from 83 patients aged <4 years with MMD were included in this study. The mean age of all surgical hemispheres at diagnosis was 2.17±0.831 years (range 0.380-3.81 years). In the multivariate logistic regression model, we included all variables with P<0.1 in the univariate analysis. The multivariate logistic regression analysis indicated that preoperative MRA grade (odds ratio [OR], 2.05 [95% confidence interval [CI], 1.3-3.25], P=0. 002), and age at diagnosis (OR, 0.61 [95% CI, 0.4-0.92], P=0. 018) were predictive factors of infarction at diagnosis. The analysis further indicated that the onset of infarction (OR, 0.01 [95% CI, 0-0.08], P<0.001), preoperative MRA grade (OR, 1.7 [95% CI, 1.03-2.8], P=0.037), and duration from diagnosis to surgery (Diag-Op) (OR, 1.25 [95% CI, 1.11-1.41], P<0.001) were predictive factors for infarction while awaiting surgery. Moreover, the regression analysis indicated that family history (OR, 8.88 [95% CI, 0.91-86.83], P=0.06), preoperative MRA grade (OR, 8.72 [95% CI, 3.44-22.07], P<0.001), age at diagnosis (OR, 0.36 [95% CI, 0.14-0.91], P=0.031), and Diag-Op (OR, 1.38 [95% CI, 1.14-1.67], P=0.001) were predictive factors for total infarction. Therefore, during the entire treatment process, careful observation, adequate risk factor management, and optimal operation time are required to prevent preoperative cerebral infarction, particularly in pediatric patients with a family history, higher preoperative MRA grade, duration from diagnosis to operation longer than 3.53 months, and aged ˂3 years at diagnosis.

Angiopoietin-2 associates with poor prognosis in Moyamoya angiopathy

OBJECTIVE

Moyamoya angiopathy (MA) is a rare cerebrovascular disorder characterized by recurrent ischemic/hemorrhagic strokes due to progressive occlusion of the intracranial carotid arteries. The lack of reliable disease severity biomarkers led us to investigate molecular features of a Caucasian cohort of MA patients.

METHODS

The participants consisted of 30 MA patients and 40 controls. We measured cerebrospinal fluid (CSF) levels of angiogenic/inflammatory factors (ELISA). We then applied quantitative real-time PCR on cerebral artery specimens for expression analyses of angiogenic factors. By an immunoassay based on microfluidic technology, we examined the potential correlations between plasma protein expression and MA clinical progression. A RNA interference approach toward Ring Finger Protein 213 (RNF213) and a tube formation assay were applied in cellular model.

RESULTS

We detected a statistically significant (p < 0.000001) up-regulation of Angiopoietin-2 (Ang-2) in CSF and stenotic middle cerebral arteries (RQ >2) of MA patients compared to controls. A high Ang-2 plasma concentration (p = 0.018) was associated with unfavorable outcome in a subset of MA patients. ROC curve analyses indicated Ang-2 as diagnostic CSF biomarker (>3741 pg/mL) and prognostic plasma biomarker (>1162 pg/mL), to distinguish stable-from-progressive MA. Consistently, MA cellular model showed a significant up-regulation (RQ >2) of Ang-2 in RNF213 silenced condition.

INTERPRETATION

Our results pointed out Ang-2 as a reliable biomarker mirroring arterial steno-occlusion and vascular instability of MA in CSF and blood, providing a candidate factor for patient stratification. This pilot study may pave the way to the validation of a biomarker to identify progressive MA patients deserving a specific treatment path.

RNF213 Polymorphisms in Intracranial Artery Dissection

The ring finger protein 213 gene (RNF213) is involved in several vascular diseases, both intracranial and systemic ones. Some variants are common in the Asian population and are reported as a risk factor for moyamoya disease, intracranial stenosis and intracranial aneurysms. Among intracranial vascular diseases, both moyamoya disease and intracranial artery dissection are more prevalent in the Asian population. We performed a systematic review of the literature, aiming to assess the rate of RNF213 variants in patients with spontaneous intracranial dissections. Four papers were identified, providing data on 53 patients with intracranial artery dissection. The rate of RNF213 variants is 10/53 (18.9%) and it increases to 10/29 (34.5%), excluding patients with vertebral artery dissection. All patients had the RNF213 p.Arg4810Lys variant. RNF213 variants seems to be involved in intracranial dissections in Asian cohorts. The small number of patients, the inclusion of only patients of Asian descent and the small but non-negligible coexistence with moyamoya disease familiarity might be limiting factors, requiring further studies to confirm these preliminary findings and the embryological interpretation.

Molecular structure and function of mysterin/RNF213

Mysterin is a large intracellular protein harboring a RING finger ubiquitin ligase domain and is also referred to as RING finger protein 213 (RNF213). The author performed the first molecular cloning of the mysterin gene as the final step in genetic exploration of cerebrovascular moyamoya disease (MMD) and initiated the next round of exploration to understand its molecular and cellular functions. Although much remains unknown, accumulating findings suggest that mysterin functions in cells by targeting massive intracellular structures, such as lipid droplets (LDs) and various invasive pathogens. In the latter case, mysterin appears to directly surround and ubiquitylate the surface of pathogens and stimulate cell-autonomous antimicrobial reactions, such as xenophagy and inflammatory response. To date, multiple mutations causing MMD have been identified within and near the RING finger domain of mysterin; however, their functional relevance remains largely unknown. Besides the RING finger, mysterin harbors a dynein-like ATPase core and an RZ finger, another ubiquitin ligase domain unique to mysterin, while functional exploration of these domains has also just commenced. In this review, the author attempts to summarize the core findings regarding the molecular structure and function of the mysterin protein, with an emphasis on the perspective of MMD research.

Yield of genetic evaluation in non-syndromic pediatric moyamoya patients

PURPOSE

Few guidelines exist for genetic testing of patients with moyamoya arteriopathy. This study aims to characterize the yield of genetic testing of non-syndromic moyamoya patients given the current pre-test probability.

METHODS

All pediatric moyamoya patients who received revascularization surgery at one institution between 2018 and 2022 were retrospectively reviewed. Patients with previously diagnosed moyamoya syndromes or therapeutic cranial radiation were excluded.

RESULTS

Of 117 patients with moyamoya, 74 non-syndromic patients (44 females, 59%) were eligible. The median age at surgery was 8.1 years. Neurosurgeons referred 18 (24%) patients for neurogenetic evaluation. Eleven (61%) patients subsequently underwent genetic testing. Eight (73%) patients had available testing results. Five (62.5%) of these patients had developmental delay compared to 16 (22%) of the entire cohort. Six (75%) patients who underwent genetic testing were found to have at least one genetic variant. These results led to diagnosis of a new genetic disorder for 1 (12.5%) patient and screening recommendations for 2 (25%) patients. An RNF213 variant in one patient led to recommendations for family member screening and pulmonary hypertension screening. Another patient was diagnosed with CBL disorder and referred for cancer screening. The median age at surgery in patients with clinically actionable findings was 4.6 years compared to 9.2 years in those who were referred for genetic testing. All 3 patients who had an actionable finding had developmental delay.

CONCLUSION

It may be beneficial to refer moyamoya patients under 5 for genetic screening given the high likelihood of discovering actionable mutations.

De novo variants in RNF213 are associated with a clinical spectrum ranging from Leigh syndrome to early-onset stroke

PURPOSE

RNF213, encoding a giant E3 ubiquitin ligase, has been recognized for its role as a key susceptibility gene for moyamoya disease. Case reports have also implicated specific variants in RNF213 with an early-onset form of moyamoya disease with full penetrance. We aimed to expand the phenotypic spectrum of monogenic RNF213-related disease and to evaluate genotype-phenotype correlations.

METHODS

Patients were identified through reanalysis of exome sequencing data of an unselected cohort of unsolved pediatric cases and through GeneMatcher or ClinVar. Functional characterization was done by proteomics analysis and oxidative phosphorylation enzyme activities using patient-derived fibroblasts.

RESULTS

We identified 14 individuals from 13 unrelated families with (de novo) missense variants in RNF213 clustering within or around the Really Interesting New Gene (RING) domain. Individuals presented either with early-onset stroke (n = 11) or with Leigh syndrome (n = 3). No genotype-phenotype correlation could be established. Proteomics using patient-derived fibroblasts revealed no significant differences between clinical subgroups. 3D modeling revealed a clustering of missense variants in the tertiary structure of RNF213 potentially affecting zinc-binding suggesting a gain-of-function or dominant negative effect.

CONCLUSION

De novo missense variants in RNF213 clustering in the E3 RING or other regions affecting zinc-binding lead to an early-onset syndrome characterized by stroke or Leigh syndrome.

Fatal brainstem injury following proton radiation in a patient with medulloblastoma and a germline variant in RNF213

Brainstem injury occurs secondary to radiation to the posterior fossa in up to 2% of pediatric patients. It may occur after months to years after treatment. It has been associated with age less than 5 years and with comorbid conditions such as cerebrovascular disease, diabetes mellitus, and hypertension. Radiation necrosis is often symptomatic and can be fatal. A pathogenic variant in RNF213 was found in a patient who suffered fatal radiation necrosis. This mutation has been associated with moyamoya disease and may predispose to radiation necrosis.

RNF213-Related Vasculopathy: Various Systemic Vascular Diseases Involving RNF213 Gene Mutations: Review

Moyamoya disease (MMD) is a cerebrovascular disorder that is predominantly observed in women of East Asian descent, and is characterized by progressive stenosis of the internal carotid artery, beginning in early childhood, and a distinctive network of collateral vessels known as "moyamoya vessels" in the basal ganglia. Additionally, a prevalent genetic variant found in most MMD cases is the p.R4810K polymorphism of RNF213 on chromosome 17q25.3. Recent studies have revealed that RNF213 mutations are associated not only with MMD, but also with other systemic vascular disorders, including intracranial atherosclerosis and systemic vascular abnormalities such as pulmonary artery stenosis and coronary artery diseases. Therefore, the concept of "RNF213-related vasculopathy" has been proposed. This review focuses on polymorphisms in the RNF213 gene and describes a wide range of clinical and genetic phenotypes associated with RNF213-related vasculopathy. The RNF213 gene has been suggested to play an important role in the pathogenesis of vascular diseases and developing new therapies. Therefore, further research and knowledge sharing through collaboration between clinicians and researchers are required.

Arg4810Lys mutation in RNF213 among Eastern Indian non-MMD ischemic stroke patients: a genotype-phenotype correlation

INTRODUCTION

RNF213 mutations have been reported mostly in moyamoya disease (MMD) with varying frequencies across different ethnicities. However, its prevalence in non-MMD adult-onset ischemic stroke is still not well explored.

AIMS AND OBJECTIVES

This present study thus aims to screen the most common RNF213 variant (Arg4810Lys, among East Asians) in the Eastern Indian non-MMD ischemic stroke patients and correlate it with long-term progression and prognosis of the patients. The subjects were analyzed for this variant using PCR-RFLP and confirmed using Sanger sequencing method.

RESULT AND CONCLUSION

We have identified Arg4810Lys variant among eleven young-onset familial ischemic stroke patients in heterozygous manner. A positive correlation of the variant with positive family history (P = 0.001), earlier age at onset (P = 0.002), and history of recurrent stroke (P = 0.015) was observed. However, the carriers showed better cognitive performances in memory (P = 0.042) and executive function (P = 0.004). Therefore, we can conclude that Arg4810Lys/RNF213 - a pathogenic variant for young-onset familial ischemic stroke with higher incidence of recurrent events unlike in MMD cases, have no additional impact on cognition among Eastern Indians.

The Progression of Pathophysiology of Moyamoya Disease

Moyamoya disease (MMD) is a chronic steno-occlusive cerebrovascular disease that often leads to hemorrhagic and ischemic strokes; however, its etiology remains elusive. Surgical revascularization by either direct or indirect bypass techniques to restore cerebral hypoperfusion is the treatment of choice to date. This review aims to provide an overview of the current advances in the pathophysiology of MMD, including the genetic, angiogenic, and inflammatory factors related to disease progression. These factors may cause MMD-related vascular stenosis and aberrant angiogenesis in complex manners. With a better understanding of the pathophysiology of MMD, nonsurgical approaches that target the pathogenesis of MMD may be able to halt or slow the progression of this disease.

Ravages: An R package for the simulation and analysis of rare variants in multicategory phenotypes

Current software packages for the analysis and the simulations of rare variants are only available for binary and continuous traits. Ravages provides solutions in a single R package to perform rare variant association tests for multicategory, binary and continuous phenotypes, to simulate datasets under different scenarios and to compute statistical power. Association tests can be run in the whole genome thanks to C++ implementation of most of the functions, using either RAVA-FIRST, a recently developed strategy to filter and analyse genome-wide rare variants, or user-defined candidate regions. Ravages also includes a simulation module that generates genetic data for cases who can be stratified into several subgroups and for controls. Through comparisons with existing programmes, we show that Ravages complements existing tools and will be useful to study the genetic architecture of complex diseases. Ravages is available on the CRAN at https://cran.r-project.org/web/packages/Ravages/ and maintained on Github at https://github.com/genostats/Ravages.

The emerging role of E3 ubiquitin ligase RNF213 as an antimicrobial host determinant

Ring finger protein 213 (RNF213) is a large E3 ubiquitin ligase with a molecular weight of 591 kDa that is associated with moyamoya disease, a rare cerebrovascular disease. It is located in the cytosol and perinuclear space. Missense mutations in this gene have been found to be more prevalent in patients with moyamoya disease compared with that in healthy individuals. Understanding the molecular function of RNF213 could provide insights into moyamoya disease. RNF213 contains a C3HC4-type RING finger domain with an E3 ubiquitin ligase domain and six AAA+ adenosine triphosphatase (ATPase) domains. It is the only known protein with both AAA+ ATPase and ubiquitin ligase activities. Recent studies have highlighted the role of RNF213 in fighting against microbial infections, including viruses, parasites, bacteria, and chlamydiae. This review aims to summarize the recent research progress on the mechanisms of RNF213 in pathogenic infections, which will aid researchers in understanding the antimicrobial role of RNF213.

Amplified Risk of Intracranial Artery Stenosis/Occlusion Associated With RNF213 p.R4810K in Familial Hypercholesterolemia

Background

The RNF213 p.R4810K variant is associated with moyamoya disease in East Asian individuals and increases the risk of developing intracranial major artery stenosis/occlusion (ICASO) that affects anterior circulation. Meanwhile, 0.5% to 2.5% of asymptomatic East Asian individuals also carry this variant. As such, additional factors are likely required to develop ICASO in variant carriers. Familial hypercholesterolemia (FH) is a common genetic disorder in Japan that has a significant associated risk of developing premature coronary atherosclerosis; however, the relationship between ICASO and FH remains unknown.

Objectives

This study aimed to determine if FH facilitates RNF213 p.R4810K carriers to develop ICASO.

Methods

We enrolled patients with FH who had undergone brain magnetic resonance angiography at our hospital from May 2005 to March 2020. The RNF213 p.R4810K variant, and LDLR and PCSK9 mutations were genotyped. ICASO lesions in the brain magnetic resonance angiogram were analyzed.

Results

Six RNF213 p.R4810K variant carriers were identified among 167 patients with FH (LDLR, n = 104; PCSK9, n = 22). Five of the carriers (83.3%) exhibited ICASO in the anterior circulation; a significant difference in ICASO frequency was observed between the variant carriers and noncarriers (P = 0.025). The median number of stenotic or occluded arteries in the anterior circulation was also significantly larger in the variant carriers (3 vs 1, P = 0.01); however, did not differ between patients with FH with LDLR and PCSK9 mutations.

Conclusions

Patients with FH exhibit increased prevalence and severity of ICASO associated with RNF213 p.R4810K. Gene mutations for FH may confer an increased risk of ICASO in RNF213 p.R4810K carriers.

The genetic landscape and clinical implication of pediatric Moyamoya angiopathy in an international cohort

Pediatric Moyamoya Angiopathy (MMA) is a progressive intracranial occlusive arteriopathy that represents a leading cause of transient ischemic attacks and strokes in childhood. Despite this, up to now no large, exclusively pediatric MMA cohort has been subjected to systematic genetic investigation. In this study, we performed molecular karyotyping, exome sequencing and automated structural assessment of missense variants on a series of 88 pediatric MMA patients and correlated genetic, angiographic and clinical (stroke burden) findings. The two largest subgroups in our cohort consisted of RNF213 and neurofibromatosis type 1 (NF1) patients. While deleterious RNF213 variants were associated with a severe MMA clinical course with early symptom onset, frequent posterior cerebral artery involvement and higher stroke rates in multiple territories, NF1 patients had a similar infarct burden compared to non-NF1 individuals and were often diagnosed incidentally during routine MRIs. Additionally, we found that MMA-associated RNF213 variants have lower predicted functional impact compared to those associated with aortic disease. We also raise the question of MMA as a feature of recurrent as well as rare chromosomal imbalances and further support the possible association of MMA with STAT3 deficiency. In conclusion, we provide a comprehensive characterization at the genetic and clinical level of a large exclusively pediatric MMA population. Due to the clinical differences found across genetic subgroups, we propose genetic testing for risk stratification as part of the routine assessment of pediatric MMA patients.

Whole-exome sequencing in moyamoya patients of Northern-European origin identifies gene variants involved in Nitric Oxide metabolism: A pilot study

Introduction

Moyamoya disease (MMD) is a chronic cerebrovascular steno-occlusive disease of largely unknown etiology. Variants in the RNF213 gene are strongly associated with MMD in East-Asia. In MMD patients of Northern-European origin, no predominant susceptibility variants have been identified so far.

Research question

Are there specific candidate genes associated with MMD of Northern-European origin, including the known RNF213 gene? Can we establish a hypothesis for MMD phenotype and associated genetic variants identified for further research?

Material and methods

Adult patients of Northern-European origin, treated surgically for MMD at Oslo University Hospital between October 2018 to January 2019 were asked to participate. WES was performed, with subsequent bioinformatic analysis and variant filtering. The selected candidate genes were either previously reported in MMD or known to be involved in angiogenesis. The variant filtering was based on variant type, location, population frequency, and predicted impact on protein function.

Results

Analysis of WES data revealed nine variants of interest in eight genes. Five of those encode proteins involved in nitric oxide (NO) metabolism: NOS3, NR4A3, ITGAV, GRB7 and AGXT2. In the AGXT2 gene, a de novo variant was detected, not previously described in MMD. None harboured the p.R4810K missense variant in the RNF213 gene known to be associated with MMD in East-Asian patients.

Discussion and conclusion

Our findings suggest a role for NO regulation pathways in Northern-European MMD and introduce AGXT2 as a new susceptibility gene. This pilot study warrants replication in larger patient cohorts and further functional investigations.

Moyamoya Vasculopathy in Neurofibromatosis Type 1 Pediatric Patients: The Role of Rare Variants of RNF213

Neurofibromatosis type 1 (NF1) is a neurocutaneous disorder caused by mutations in NF1 gene, coding for neurofibromin 1. NF1 can be associated with Moyamoya disease (MMD), and this association, typical of paediatric patients, is referred to as Moyamoya syndrome (MMS). MMD is a cerebral arteriopathy characterized by the occlusion of intracranial arteries and collateral vessel formation, which increase the risk of ischemic and hemorrhagic events. RNF213 gene mutations have been associated with MMD, so we investigated whether rare variants of RNF213 could act as genetic modifiers of MMS phenotype in a pediatric cohort of 20 MMS children, 25 children affected by isolated MMD and 47 affected only by isolated NF1. By next-generation re-sequencing (NGS) of patients' DNA and gene burden tests, we found that RNF213 seems to play a role only for MMD occurrence, while it does not appear to be involved in the increased risk of Moyamoya for MMS patients. We postulated that the loss of neurofibromin 1 can be enough for the excessive proliferation of vascular smooth muscle cells, causing Moyamoya arteriopathy associated with NF1. Further studies will be crucial to support these findings and to elucidate the possible role of other genes, enhancing our knowledge about pathogenesis and treatment of MMS.

Biallelic variants in NOS3 and GUCY1A3, the two major genes of the nitric oxide pathway, cause moyamoya cerebral angiopathy

BACKGROUND

Moyamoya angiopathy (MMA) is a rare cerebrovascular condition leading to stroke. Mutations in 15 genes have been identified in Mendelian forms of MMA, but they explain only a very small proportion of cases. Our aim was to investigate the genetic basis of MMA in consanguineous patients having unaffected parents in order to identify genes involved in autosomal recessive MMA.

METHODS

Exome sequencing (ES) was performed in 6 consecutive consanguineous probands having MMA of unknown etiology. Functional consequences of variants were assessed using western blot and protein 3D structure analyses.

RESULTS

Causative homozygous variants of NOS3, the gene encoding the endothelial nitric oxide synthase (eNOS), and GUCY1A3, the gene encoding the alpha1 subunit of the soluble guanylate cyclase (sGC) which is the major nitric oxide (NO) receptor in the vascular wall, were identified in 3 of the 6 probands. One NOS3 variant (c.1502 + 1G > C) involves a splice donor site causing a premature termination codon and leads to a total lack of eNOS in endothelial progenitor cells of the affected proband. The other NOS3 variant (c.1942 T > C) is a missense variant located into the flavodoxine reductase domain; it is predicted to be destabilizing and shown to be associated with a reduction of eNOS expression. The GUCY1A3 missense variant (c.1778G > A), located in the catalytic domain of the sGC, is predicted to disrupt the tridimensional structure of this domain and to lead to a loss of function of the enzyme. Both NOS3 mutated probands suffered from an infant-onset and severe MMA associated with posterior cerebral artery steno-occlusive lesions. The GUCY1A3 mutated proband presented an adult-onset MMA associated with an early-onset arterial hypertension and a stenosis of the superior mesenteric artery. None of the 3 probands had achalasia.

CONCLUSIONS

We show for the first time that biallelic loss of function variants in NOS3 is responsible for MMA and that mutations in NOS3 and GUCY1A3 are causing fifty per cent of MMA in consanguineous patients. These data pinpoint the essential role of the NO pathway in MMA pathophysiology.

Increasing precision in the management of pediatric neurosurgical cerebrovascular diseases with molecular genetics

Recent next-generation DNA and RNA sequencing studies of congenital and pediatric cerebrovascular anomalies such as moyamoya disease, arteriovenous malformations, vein of Galen malformations, and cavernous malformations have shed new insight into the genetic regulation of human cerebrovascular development by implicating multiple novel disease genes and signaling pathways in the pathogenesis of these disorders. These diseases are now beginning to be categorized by molecular disruptions in canonical signaling pathways that impact the differentiation and proliferation of specific venous, capillary, or arterial cells during the hierarchical development of the cerebrovascular system. Here, the authors discuss how the continued study of these and other congenital cerebrovascular conditions has the potential to replace the current antiquated, anatomically based disease classification systems with a molecular taxonomy that has the potential to increase precision in genetic counseling, prognostication, and neurosurgical and endovascular treatment stratification. Importantly, the authors also discuss how molecular genetic data are already informing clinical trials and catalyzing the development of targeted therapies for these conditions historically considered as exclusively neurosurgical lesions.

European Stroke Organisation (ESO) Guidelines on Moyamoya angiopathy: Endorsed by Vascular European Reference Network (VASCERN)

The European Stroke Organisation (ESO) guidelines on Moyamoya Angiopathy (MMA), developed according to ESO standard operating procedure and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology, were compiled to assist clinicians in managing patients with MMA in their decision making. A working group involving neurologists, neurosurgeons, a geneticist and methodologists identified nine relevant clinical questions, performed systematic literature reviews and, whenever possible, meta-analyses. Quality assessment of the available evidence was made with specific recommendations. In the absence of sufficient evidence to provide recommendations, Expert Consensus Statements were formulated. Based on low quality evidence from one RCT, we recommend direct bypass surgery in adult patients with haemorrhagic presentation. For ischaemic adult patients and children, we suggest revascularization surgery using direct or combined technique rather than indirect, in the presence of haemodynamic impairment and with an interval of 6–12 weeks between the last cerebrovascular event and surgery. In the absence of robust trial, an Expert Consensus was reached recommending long-term antiplatelet therapy in non-haemorrhagic MMA, as it may reduce risk of embolic stroke. We also agreed on the utility of performing pre- and post- operative haemodynamic and posterior cerebral artery assessment. There were insufficient data to recommend systematic variant screening of RNF213 p.R4810K. Additionally, we suggest that long-term MMA neuroimaging follow up may guide therapeutic decision making by assessing the disease progression. We believe that this guideline, which is the first comprehensive European guideline on MMA management using GRADE methods will assist clinicians to choose the most effective management strategy for MMA.

Increase of Circulating Endothelial Progenitor Cells and Released Angiogenic Factors in Children with Moyamoya Arteriopathy

Moyamoya arteriopathy (MMA) is a rare cerebrovascular disorder that causes recurrent ischemic and hemorrhagic strokes, leading young patients to severe neurological deficits. The pathogenesis of MMA is still unknown. The disease onset in a wide number of pediatric cases raises the question of the role of genetic factors in the disease's pathogenesis. In these patients, MMA's clinical course, or progression, is largely unclear. By performing a comprehensive molecular and cellular profile in the plasma and CSF, respectively, of MMA pediatric patients, our study is aimed at assessing the levels of circulating endothelial progenitor cells (cEPC) and the release of selected proteins at an early disease stage to clarify MMA pathogenesis and progression. We employed cytofluorimetric methods and immunoassays in pediatric MMA patients and matched control subjects by age and sex. We detected increased levels of cEPC in peripheral blood and an upregulation of angiogenic markers in CSF (i.e., angiopoietin-2 and VEGF-A). This finding is probably associated with deregulated angiogenesis, as stated by the moderate severity of collateral vessel network development (Suzuki III-IV). The absence of significant modulation of neurofilament light in CSF led us to rule out the presence of substantial neuronal injury in MMA children. Despite the limited cohort of pediatric patients, we found some peculiar cellular and molecular characteristics in their blood and CSF samples. Our findings may be confirmed by wider and perspective studies to identify predictive or prognostic circulating biomarkers and potential therapeutic targets for personalized care of MMA pediatric patients.

Testing for association with rare variants in the coding and non-coding genome: RAVA-FIRST, a new approach based on CADD deleteriousness score

Rare variant association tests (RVAT) have been developed to study the contribution of rare variants widely accessible through high-throughput sequencing technologies. RVAT require to aggregate rare variants in testing units and to filter variants to retain only the most likely causal ones. In the exome, genes are natural testing units and variants are usually filtered based on their functional consequences. However, when dealing with whole-genome sequence (WGS) data, both steps are challenging. No natural biological unit is available for aggregating rare variants. Sliding windows procedures have been proposed to circumvent this difficulty, however they are blind to biological information and result in a large number of tests. We propose a new strategy to perform RVAT on WGS data: “RAVA-FIRST” (RAre Variant Association using Functionally-InfoRmed STeps) comprising three steps. (1) New testing units are defined genome-wide based on functionally-adjusted Combined Annotation Dependent Depletion (CADD) scores of variants observed in the gnomAD populations, which are referred to as “CADD regions”. (2) A region-dependent filtering of rare variants is applied in each CADD region. (3) A functionally-informed burden test is performed with sub-scores computed for each genomic category within each CADD region. Both on simulations and real data, RAVA-FIRST was found to outperform other WGS-based RVAT. Applied to a WGS dataset of venous thromboembolism patients, we identified an intergenic region on chromosome 18 enriched for rare variants in early-onset patients. This region that was missed by standard sliding windows procedures is included in a TAD region that contains a strong candidate gene. RAVA-FIRST enables new investigations of rare non-coding variants in complex diseases, facilitated by its implementation in the R package Ravages.

Mystery(n) Phenotypic Presentation in Europeans: Report of Three Further Novel Missense RNF213 Variants Leading to Severe Syndromic Forms of Moyamoya Angiopathy and Literature Review

Moyamoya angiopathy (MMA) is a rare cerebral vasculopathy in some cases occurring in children. Incidence is higher in East Asia, where the heterozygous p.Arg4810Lys variant in RNF213 (Mysterin) represents the major susceptibility factor. Rare variants in RNF213 have also been found in European MMA patients with incomplete penetrance and are today a recognized susceptibility factor for other cardiovascular disorders, from extracerebral artery stenosis to hypertension. By whole exome sequencing, we identified three rare and previously unreported missense variants of RNF213 in three children with early onset of bilateral MMA, and subsequently extended clinical and radiological investigations to their carrier relatives. Substitutions all involved highly conserved residues clustered in the C-terminal region of RNF213, mainly in the E3 ligase domain. Probands showed a de novo occurring variant, p.Phe4120Leu (family A), a maternally inherited heterozygous variant, p.Ser4118Cys (family B), and a novel heterozygous variant, p.Glu4867Lys, inherited from the mother, in whom it occurred de novo (family C). Patients from families A and C experienced transient hypertransaminasemia and stenosis of extracerebral arteries. Bilateral MMA was present in the proband’s carrier grandfather from family B. The proband from family C and her carrier mother both exhibited annular figurate erythema. Our data confirm that rare heterozygous variants in RNF213 cause MMA in Europeans as well as in East Asian populations, suggesting that substitutions close to positions 4118–4122 and 4867 of RNF213 could lead to a syndromic form of MMA showing elevated aminotransferases and extracerebral vascular involvement, with the possible association of peculiar skin manifestations.

Transcriptomic Profiling of Intracranial Arteries in Adult Patients With Moyamoya Disease Reveals Novel Insights Into Its Pathogenesis

Moyamoya disease (MMD) is a rare, progressively steno-occlusive cerebrovascular disorder of unknown etiology. Here, we revealed the gene expression profile of the intracranial arteries in MMD via the RNA-sequencing (RNA-seq). We identified 556 differentially expressed genes (DEGs) for MMD, including 449 and 107 significantly upregulated or downregulated genes. Compared with atherosclerosis-associated intracranial artery stenosis/occlusion (AS-ICASO) controls, upregulated genes were mainly involved in extracellular matrix (ECM) organization, whereas downregulated genes were primarily associated with mitochondrial function and oxidative phosphorylation in MMD. Moreover, we found that a separate sex analysis uncovers more DEGs (n = 1.022) compared to an combined sex analysis in MMD. We identified 133 and 439 sex-specific DEGs for men and women in MMD, respectively. About 95.6% of sex-specific DEGs were protein-coding genes and 3% of the genes belonged to long non-coding RNAs (lncRNA). Sex-specific DEGs were observed on all chromosomes, of which 95.49 and 96.59% were autosomal genes in men and women, respectively. These sex-specific DEGs, such as aquaporin-4 (AQP4), superoxide dismutase 3 (SOD3), and nuclear receptor subfamily 4 group A member 1 (NR4A1), may contribute to sex differences in MMD. This transcriptomic study highlighted that ECM and mitochondrial function are the central molecular mechanisms underlying MMD, and revealed sex differences in the gene expression in the intracranial arteries, thereby providing new insights into the pathogenesis of MMD.

Association of RNF213 Variants With Periventricular Anastomosis in Moyamoya Disease

BACKGROUND

The pathogenic mechanisms of periventricular anastomosis (PA) in moyamoya disease remain unknown. Here, we aimed to describe the angiographic profiles of PA and their relationships with really interesting new gene (RING) finger protein 213 (RNF213) genotypes.

METHODS

We conducted a retrospective cohort study of moyamoya disease patients consecutively recruited between June 2019 and January 2021 in Beijing Tiantan Hospital, Capital Medical University, China. C-terminal region of RNF213 was sequenced. Angiographic characteristics of PA vessels (lenticulostriate artery, thalamotuberal artery, thalamoperforating artery, anterior choroidal artery, and posterior choroidal artery) were compared between different groups of RNF213 genotypes. The dilatation and extension of PA vessels were measured by using PA score (positive, score 1-5; negative, score 0). Multivariate regression analysis was conducted to assess variables associated with PA score. In addition, gene expression of RNF213 in human brain regions was evaluated from the Allen Human Brain Atlas.

RESULTS

Among 260 patients (484 hemispheres), 71.2% carried no RNF213 rare and novel variants, 20.0% carried p.R4810K heterozygotes, and 8.8% carried other rare and novel variants. PA scores in patients with p.R4810K and other rare and novel variants were significantly higher than in wild-type patients (P<0.001). Age (odds ratio [OR], 0.958 [95% CI, 0.942-0.974]; P<0.001), platelet count (OR, 0.996 [95% CI, 0.992-0.999]; P=0.027), p.R4810K variant (OR, 2.653 [95% CI, 1.514-4.649]; P=0.001), other rare and novel variants (OR, 3.197 [95% CI, 1.012-10.094]; P=0.048), Suzuki stage ≥4 (OR, 1.941 [95% CI, 1.138-3.309]; P=0.015), and posterior cerebral artery involvement (OR, 1.827 [95% CI, 1.020-3.271]; P=0.043) were significantly correlated with PA score. High expression of RNF213 was detected in the periventricular area.

CONCLUSIONS

RNF213 variants were confirmed to be associated with PA in moyamoya disease. Individuals with RNF213 p.R4810K heterozygotes and other C-terminal region rare variants exhibited different angiographic phenotypes, compared with wild-type patients.

Novel Multifaceted Roles for RNF213 Protein

Ring Finger Protein 213 (RNF213), also known as Mysterin, is the major susceptibility factor for Moyamoya Arteriopathy (MA), a progressive cerebrovascular disorder that often leads to brain stroke in adults and children. Although several rare RNF213 polymorphisms have been reported, no major susceptibility variant has been identified to date in Caucasian patients, thus frustrating the attempts to identify putative therapeutic targets for MA treatment. For these reasons, the investigation of novel biochemical functions, substrates and unknown partners of RNF213 will help to unravel the pathogenic mechanisms of MA and will facilitate variant interpretations in a diagnostic context in the future. The aim of the present review is to discuss novel perspectives regarding emerging RNF213 roles in light of recent literature updates and dissect their relevance for understanding MA and for the design of future research studies. Since its identification, RNF213 involvement in angiogenesis and vasculogenesis has strengthened, together with its role in inflammatory signals and proliferation pathways. Most recent studies have been increasingly focused on its relevance in antimicrobial activity and lipid metabolism, highlighting new intriguing perspectives. The last area could suggest the main role of RNF213 in the proteasome pathway, thus reinforcing the hypotheses already previously formulated that depict the protein as an important regulator of the stability of client proteins involved in angiogenesis. We believe that the novel evidence reviewed here may contribute to untangling the complex and still obscure pathogenesis of MA that is reflected in the lack of therapies able to slow down or halt disease progression and severity.

RAVAQ: An integrative pipeline from quality control to region-based rare variant association analysis

Next-generation sequencing technologies have opened up the possibility to sequence large samples of cases and controls to test for association with rare variants. To limit cost and increase sample sizes, data from controls could be used in multiple studies and might thus be generated on different sequencing platforms. This could pose some problems of comparability between cases and controls due to batch effects that could be confounding factors, leading to false-positive association signals. To limit batch effects and ensure comparability of datasets, stringent quality controls are required. We propose an integrative five-steps pipeline, RAVAQ, that (a) performs a specific three-step quality control taking into account the case-control status to ensure data comparability, (b) selects qualifying variants as defined by the user, and (c) performs rare variant association tests per genomic region. The RAVAQ pipeline is wrapped in an R package. It is user-friendly and flexible in its arguments to adapt to the specificity of each research project. We provide examples showing how RAVAQ improves rare variant association tests. The default RAVAQ quality control outperformed the widely used Variant Quality Score Recalibration method, removing inflation due to spurious signals. RAVAQ is open source and freely available at https://gitlab.com/gmarenne/ravaq.

RNF213-Associated Vascular Disease: A Concept Unifying Various Vasculopathies

The ring finger protein 213 gene (RNF213) encodes a 590 kDa protein that is thought to be involved in angiogenesis. This gene was first recognized as a vasculopathy-susceptibility locus through genome-wide association studies undertaken in a Japanese population, demonstrating that heterozygotes for RNF213 p.Arg4810Lys (c.14429G>A, rs112735431) had a greatly increased risk of moyamoya disease. The association of RNF213 p.Arg4810Lys as a susceptibility variant of moyamoya disease was reproduced in Korean and Chinese individuals and, later, in Caucasians. Variants of the RNF213 gene have been linked to a number of vascular diseases such as moyamoya disease, intracranial major artery stenosis, pulmonary arterial hypertension, and peripheral pulmonary artery stenosis, and have also been associated with co-occurrent diseases and vascular disease in different organs. Based on the findings that we have reported to date, our paper proposes a new concept of “RNF213-associated vascular disease” to unify these conditions with the aim of capturing patients with multiple diseases but with a common genetic background. This concept will be highly desirable for clarifying all of the diseases in the RNF213-associated vascular disease category by means of global epidemiological investigations because of the possibility of such diseases appearing asymptomatically in some patients.

MMD-associated RNF213 SNPs encode dominant-negative alleles that globally impair ubiquitylation

MMD-associated SNPs of RNF213 encode dominant-negative alleles that globally impair ubiquitylation by RNF213-UBE2D2.

Single-nucleotide polymorphisms (SNPs) in RNF213, which encodes a 591-kD protein with AAA+ ATPase and RING E3 domains, are associated with a rare, autosomal dominant cerebrovascular disorder, moyamoya disease (MMD). MMD-associated SNPs primarily localize to the C-terminal region of RNF213, and some affect conserved residues in the RING domain. Although the autosomal dominant inheritance of MMD could most easily explained by RNF213 gain-of-function, the type of ubiquitylation catalyzed by RNF213 and the effects of MMD-associated SNPs on its E3 ligase activity have remained unclear. We found that RNF213 uses the E2-conjugating enzymes UBE2D2 and UBE2L3 to catalyze distinct ubiquitylation events. RNF213-UBED2 catalyzes K6 and, to a lesser extent, K48-dependent poly-ubiquitylation in vitro, whereas RNF213-UBE2L3 catalyzes K6-, K11-, and K48-dependent poly-ubiquitylation events. MMD-associated SNPs encode proteins with decreased E3 activity, and the most frequent MMD allele, RNF213^R4810K, is a dominant-negative mutant that decreases ubiquitylation globally. By contrast, MMD-associated RNF213 SNPs do not affect ATPase activity. Our results suggest that decreased RNF213 E3 ligase activity is central to MMD pathogenesis.

Macrohistory of Moyamoya Disease Analyzed Using Artificial Intelligence

INTRODUCTION

Moyamoya disease is characterized by progressive stenotic changes in the terminal segment of the internal carotid artery and the development of abnormal vascular networks called moyamoya vessels. The objective of this review was to provide a holistic view of the epidemiology, etiology, clinical findings, treatment, and pathogenesis of moyamoya disease. A literature search was performed in PubMed using the term "moyamoya disease," for articles published until 2021.

RESULTS

Artificial intelligence (AI) clustering was used to classify the articles into 5 clusters: (1) pathophysiology (23.5%); (2) clinical background (37.3%); (3) imaging (13.2%); (4) treatment (17.3%); and (5) genetics (8.7%). Many articles in the "clinical background" cluster were published from the 1970s. However, in the "treatment" and "genetics" clusters, the articles were published from the 2010s through 2021. In 2011, it was confirmed that a gene called Ringin protein 213 (RNF213) is a susceptibility gene for moyamoya disease. Since then, tremendous progress in genomic, transcriptomic, and epigenetic profiling (e.g., methylation profiling) has resulted in new concepts for classifying moyamoya disease. Our literature survey revealed that the pathogenesis involves aberrations of multiple signaling pathways through genetic mutations and altered gene expression.

CONCLUSION

We analyzed the content vectors in abstracts using AI, and reviewed the pathophysiology, clinical background, radiological features, treatments, and genetic peculiarity of moyamoya disease.

Plasma Lipid Profiling Contributes to Untangle the Complexity of Moyamoya Arteriopathy

Moyamoya arteriopathy (MA) is a rare cerebrovascular disorder characterized by ischemic/hemorrhagic strokes. The pathophysiology is unknown. A deregulation of vasculogenic/angiogenic/inflammatory pathways has been hypothesized as a possible pathophysiological mechanism. Since lipids are implicated in modulating neo-vascularization/angiogenesis and inflammation, their deregulation is potentially involved in MA. Our aim is to evaluate angiogenic/vasculogenic/inflammatory proteins and lipid profile in plasma of MA patients and control subjects (healthy donors HD or subjects with atherosclerotic cerebrovascular disease ACVD). Angiogenic and inflammatory protein levels were measured by ELISA and a complete lipidomic analysis was performed on plasma by mass spectrometry. ELISA showed a significant decrease for MMP-9 released in plasma of MA. The untargeted lipidomic analysis showed a cumulative depletion of lipid asset in plasma of MA as compared to HD. Specifically, a decrease in membrane complex glycosphingolipids peripherally circulating in MA plasma with respect to HD was observed, likely suggestive of cerebral cellular recruitment. The quantitative targeted approach demonstrated an increase in free sphingoid bases, likely associated with a deregulated angiogenesis. Our findings indicate that lipid signature could play a central role in MA and that a detailed biomarker profile may contribute to untangle the complex, and still obscure, pathogenesis of MA.

Proteome Profiling of RNF213 Depleted Cells Reveals Nitric Oxide Regulator DDAH1 Antilisterial Activity

RNF213 is a large, poorly characterized interferon-induced protein. Mutations in RNF213 are associated with predisposition for Moyamoya disease (MMD), a rare cerebrovascular disorder. Recently, RNF213 was found to have broad antimicrobial activity in vitro and in vivo, yet the molecular mechanisms behind this function remain unclear. Using mass spectrometry-based proteomics and validation by real-time PCR we report here that knockdown of RNF213 leads to transcriptional upregulation of MVP and downregulation of CYR61, in line with reported pro- and anti-bacterial activities of these proteins. Knockdown of RNF213 also results in downregulation of DDAH1, which we discover to exert antimicrobial activity against Listeria monocytogenes infection. DDAH1 regulates production of nitric oxide (NO), a molecule with both vascular and antimicrobial effects. We show that NO production is reduced in macrophages from RNF213 KO mice, suggesting that RNF213 controls Listeria infection through regulation of DDAH1 transcription and production of NO. Our findings propose a potential mechanism for the antilisterial activity of RNF213 and highlight NO as a potential link between RNF213-mediated immune responses and the development of MMD.

Preoperative clinical symptomatology and stroke burden in pediatric moyamoya angiopathy: Defining associated risk variables

OBJECTIVE

To evaluate the preoperative clinical and magnetic resonance imaging and angiography (MRI-MRA) characteristics in pediatric moyamoya patients.

METHODS

Analysis included 100 children with moyamoya angiopathy referred to our moyamoya center for preoperative evaluation. Clinical symptoms, neurological status using Pediatric Stroke Outcome Measurement (PSOM) and degree of disability on modified Rankin scale score (mRS) were evaluated. MRI-MRA evaluation included the assessment of ischemic lesions and involvement of posterior circulation. Data were analyzed for moyamoya disease (MMD), moyamoya syndrome (MMS) and age at disease onset.

RESULTS

Stroke was a common presentation in both MMD and MMS patients. TIAs and headaches/migraine were more frequent in MMD. There was no evidence of a difference in stroke burden on MRI as well as in PCA involvement between the two subgroups. Children <2 years had higher odds of having a stroke (OR 15.5, 95% CI 3.8-62.4, p < 0.001), recurrent stroke (OR 11.8, 95%CI 2.9-46.7, p < 0.001) and unfavorable mRS (≥2) (OR 4.2, 95% CI 1.3-13.7, p = 0.01) when compared to those >5 years of age. There was some evidence of association of PCA involvement with recurrent strokes (OR 3.1, CI 1.0-9.6, p = 0.05), a poor PSOM (OR 3.0, 95% CI 1.1-8.2, p = 0.04) and mRS (OR 3.1, 95% CI 1.2-8.3, p = 0.02).

CONCLUSION

Stroke seems to be a common presentation in both MMD and MMS patients. Early age at symptom onset and involvement of posterior circulation seem to be important risk factors for a high stroke burden and an unfavorable PSOM and mRS.

Moyamoya disease associated with pediatric pulmonary hypertension-a case report

Moyamoya disease (MD) is a rare vaso-occlusive disorder that primarily affects intracranial cerebral arteries. The involvement of extracranial vessels is unusual. However, there are previous reports suggesting MD to be a systemic disorder, causing disease manifestations in vessels of other parts of the body. We report the case of a female patient with MD and multiple episodes of ischemic strokes followed by bypass surgery of cerebral arteries during infancy. Due to corresponding ischemic lesions the girl showed global retardation of psychomotor development and central right sided movement disorder. At the age of 10 years the girl was admitted to our hospital with recurrent syncope. While cranial MRI excluded any newly added ischemic lesions, electrocardiography revealed evidence of right ventricular hypertrophy, and subsequent echocardiography then indicated pulmonary hypertension, which was confirmed by cardiac catheterization. Despite an upfront combination pulmonary vasodilating therapy, the pulmonary vascular disease appeared to be progressive. Genetic analysis showed heterozygous c.12341C>T mutation in the RNF213 gene. This case presentation demonstrates that pulmonary arterial hypertension is a rare comorbidity in patients with MD, especially in patients with genetic predictors such as the RNF213 mutation. Thus, regular echocardiographic screening for early signs of pulmonary arterial hypertension in patients with MD should be part of regular clinical work-up. Early detection and treatment of pulmonary arterial hypertension in MD might help to improve the long-term outcome in the individual patient.