Mapping of a familial moyamoya disease gene to chromosome 3p24.2-p26

Physiological and pathophysiological mechanisms of the molecular and cellular biology of angiogenesis and inflammation in moyamoya angiopathy and related vascular diseases

Rationale

The etiology and pathophysiological mechanisms of moyamoya angiopathy (MMA) remain largely unknown. MMA is a progressive, occlusive cerebrovascular disorder characterized by recurrent ischemic and hemorrhagic strokes; with compensatory formation of an abnormal network of perforating blood vessels that creates a collateral circulation; and by aberrant angiogenesis at the base of the brain. Imbalance of angiogenic and vasculogenic mechanisms has been proposed as a potential cause of MMA. Moyamoya vessels suggest that aberrant angiogenic, arteriogenic, and vasculogenic processes may be involved in the pathophysiology of MMA. Circulating endothelial progenitor cells have been hypothesized to contribute to vascular remodeling in MMA. MMA is associated with increased expression of angiogenic factors and proinflammatory molecules. Systemic inflammation may be related to MMA pathogenesis.

Objective

This literature review describes the molecular mechanisms associated with cerebrovascular dysfunction, aberrant angiogenesis, and inflammation in MMA and related cerebrovascular diseases along with treatment strategies and future research perspectives.

Methods and results

References were identified through a systematic computerized search of the medical literature from January 1, 1983, through July 29, 2022, using the PubMed, EMBASE, BIOSIS Previews, CNKI, ISI web of science, and Medline databases and various combinations of the keywords "moyamoya," "angiogenesis," "anastomotic network," "molecular mechanism," "physiology," "pathophysiology," "pathogenesis," "biomarker," "genetics," "signaling pathway," "blood-brain barrier," "endothelial progenitor cells," "endothelial function," "inflammation," "intracranial hemorrhage," and "stroke." Relevant articles and supplemental basic science articles almost exclusively published in English were included. Review of the reference lists of relevant publications for additional sources resulted in 350 publications which met the study inclusion criteria. Detection of growth factors, chemokines, and cytokines in MMA patients suggests the hypothesis of aberrant angiogenesis being involved in MMA pathogenesis. It remains to be ascertained whether these findings are consequences of MMA or are etiological factors of MMA.

Conclusions

MMA is a heterogeneous disorder, comprising various genotypes and phenotypes, with a complex pathophysiology. Additional research may advance our understanding of the pathophysiology involved in aberrant angiogenesis, arterial stenosis, and the formation of moyamoya collaterals and anastomotic networks. Future research will benefit from researching molecular pathophysiologic mechanisms and the correlation of clinical and basic research results.

The Genetic Landscape of Ischemic Stroke in Children - Current Knowledge and Future Perspectives

Stroke in childhood has multiple etiologies, which are mostly distinct from those in adults. Genetic discoveries over the last decade pointed to monogenic disorders as a rare but significant cause of ischemic stroke in children and young adults, including small vessel and arterial ischemic stroke. These discoveries contributed to the understanding that stroke in children may be a sign of an underlying genetic disease. The identification of these diseases requires a detailed medical and family history collection, a careful clinical evaluation for the detection of systemic symptoms and signs, and neuroimaging assessment. Establishing an accurate etiological diagnosis and understanding the genetic risk factors for stroke are essential steps to decipher the underlying mechanisms, optimize the design of tailored prevention strategies, and facilitate the identification of novel therapeutic targets in some cases. Despite the increasing recognition of monogenic causes of stroke, genetic disorders remain understudied and therefore under-recognized in children with stroke. Increased awareness among healthcare providers is essential to facilitate accurate diagnosis in a timely manner. In this review, we provide a summary of the main single-gene disorders which may present as ischemic stroke in childhood and describe their clinical manifestations. We provide a set of practical suggestions for the diagnostic work up of these uncommon causes of stroke, based upon the stroke subtype and imaging characteristics that may suggest a monogenic diagnosis of ischemic stroke in children. Current hurdles in the genetic analyses of children with ischemic stroke as well as future prospectives are discussed.

Cerebral Hemorrhage: Pathophysiology, Treatment, and Future Directions

Intracerebral hemorrhage (ICH) is a devastating form of stroke with high morbidity and mortality. This review article focuses on the epidemiology, cause, mechanisms of injury, current treatment strategies, and future research directions of ICH. Incidence of hemorrhagic stroke has increased worldwide over the past 40 years, with shifts in the cause over time as hypertension management has improved and anticoagulant use has increased. Preclinical and clinical trials have elucidated the underlying ICH cause and mechanisms of injury from ICH including the complex interaction between edema, inflammation, iron-induced injury, and oxidative stress. Several trials have investigated optimal medical and surgical management of ICH without clear improvement in survival and functional outcomes. Ongoing research into novel approaches for ICH management provide hope for reducing the devastating effect of this disease in the future. Areas of promise in ICH therapy include prognostic biomarkers and primary prevention based on disease pathobiology, ultra-early hemostatic therapy, minimally invasive surgery, and perihematomal protection against inflammatory brain injury.

Moyamoya disease with Sjogren disease and autoimmune thyroiditis presenting with left intracranial hemorrhage after messenger RNA-1273 vaccination: A case report

RATIONALE

The new vaccines are emergently authorized and currently approved for use to protect against the coronavirus disease 2019 (COVID-19) pandemic and serious adverse events are uncommon. Moyamoya disease (MMD) with autoimmune disease is a rare entity and usually presents with intracranial hemorrhage in adults.

PATIENT CONCERNS

We reported a 40-year-old female patient with Sjogren disease and autoimmune thyroiditis, who had received the second dose of Moderna (mRNA-1273) vaccination. Three days later, she presented with left intraventricular and intracerebral hemorrhage as a complication.

DIAGNOSIS

After a series of diagnostic workups, left intracranial hemorrhage was associated with MMD.

INTERVENTIONS

Emergent external ventricular drainage and subsequent stereotactic evacuation of hematoma with insertion of intracranial pressure monitoring were performed.

OUTCOMES

Under the care of the neurocritical care team, her physical condition improved gradually. The neurological sequelae was noted by defects of cognitive function, apraxia, agnosia, and impaired executive function. She was discharged after eight weeks with a follow-up in the vascular neurology clinic planning for performing revascularization.

LESSONS

To the best of our knowledge, no similar case has been reported before, and this is the first case of MMD complicated with intracerebral and intraventricular hemorrhage after mRNA-1273 vaccination. It is noticeable to assess the vaccine safety surveillance and raise the alertness about moyamoya in patients with autoimmune diseases during the COVID-19 pandemic. Further studies for risk evaluation of COVID-19 vaccines in patients with autoimmune diseases might be required in the future.

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.

Moyamoya Disease in a Young Female With Neurofibromatosis Type 1

Moyamoya disease (MMD) is a rare cerebrovascular disease characterized by progressive stenosis of the terminal portions of the internal carotid arteries (ICAs) and the development of a network of abnormal collateral vessels. This case depicts a 25-year-old African American female patient with neurofibromatosis type 1 (NF-1), whose initial hospital presentation occurred in a hypertensive emergency setting. Surveillance studies with magnetic resonance imaging (MRI) revealed multiple asymptomatic right cortical strokes. Genetic testing evidenced a novel, unique pathogenic variant on the NF-1 gene. The patient underwent combined bypass surgery first and then was placed on aspirin and a blood pressure control regimen. Our case illustrates the need for clinicians to include moyamoya disease in the list of differential diagnoses when encountering a young patient, without major risk factors, presenting with ischemic stroke. It should be considered even with no known history of previously diagnosed MMD or NF-1, as these pathologies may have yet to be evaluated in subclinical cases.

The Genetic Basis of Moyamoya Disease

Moyamoya disease (MMD) is a rare cerebrovascular disease characterized by progressive spontaneous bilateral occlusion of the intracranial internal cerebral arteries (ICA) and their major branches with compensatory capillary collaterals resembling a “puff of smoke” (Japanese: Moyamoya) on cerebral angiography. These pathological alterations of the vessels are called Moyamoya arteriopathy or vasculopathy and a further distinction is made between primary and secondary MMD. Clinical presentation depends on age and population, with hemorrhage and ischemic infarcts in particular leading to severe neurological dysfunction or even death. Although the diagnostic suspicion can be posed by MRA or CTA, cerebral angiography is mandatory for diagnostic confirmation. Since no therapy to limit the stenotic lesions or the development of a collateral network is available, the only treatment established so far is surgical revascularization. The pathophysiology still remains unknown. Due to the early age of onset, familial cases and the variable incidence rate between different ethnic groups, the focus was put on genetic aspects early on. Several genetic risk loci as well as individual risk genes have been reported; however, few of them could be replicated in independent series. Linkage studies revealed linkage to the 17q25 locus. Multiple studies on the association of SNPs and MMD have been conducted, mainly focussing on the endothelium, smooth muscle cells, cytokines and growth factors. A variant of the RNF213 gene was shown to be strongly associated with MMD with a founder effect in the East Asian population. Although it is unknown how mutations in the RNF213 gene, encoding for a ubiquitously expressed 591 kDa cytosolic protein, lead to clinical features of MMD, RNF213 has been confirmed as a susceptibility gene in several studies with a gene dosage-dependent clinical phenotype, allowing preventive screening and possibly the  development of new therapeutic approaches. This review focuses on the genetic basis of primary MMD only.

Increased Autoimmunity in Individuals With Down Syndrome and Moyamoya Disease

Objective: To determine if elevated rates of autoimmune disease are present in children with both Down syndrome and moyamoya disease given the high rates of autoimmune disease reported in both conditions and unknown etiology of angiopathy in this population. Methods: A multi-center retrospective case-control study of children with Down syndrome and moyamoya syndrome, idiopathic moyamoya disease, and Down syndrome without cerebrovascular disease was performed. Outcome measures included presence of autoimmune disease, presence of autoantibodies and angiopathy severity data. Comparisons across groups was performed using the Kruskal-Wallis, χ2 and multivariate Poisson regression. Results: The prevalence of autoimmune disease were 57.7, 20.3, and 35.3% in persons with Down syndrome and moyamoya syndrome, idiopathic moyamoya disease, and Down syndrome only groups, respectively (p < 0.001). The prevalence of autoimmune disease among children with Down syndrome and moyamoya syndrome is 3.2 times (p < 0.001, 95% CI: 1.82-5.58) higher than the idiopathic moyamoya group and 1.5 times (p = 0.002, 95% CI: 1.17-1.99) higher than the Down syndrome only group when adjusting for age and sex. The most common autoimmune diseases were thyroid disorders, type I diabetes and Celiac disease. No individuals with idiopathic moyamoya disease had more than one type of autoimmune disorder while 15.4% of individuals with Down syndrome and moyamoya syndrome and 4.8% of individuals with Down syndrome only had >1 disorder (p = 0.05, 95%CI: 1.08-6.08). Interpretation: This study reports elevated rates of autoimmune disease in persons with Down syndrome and moyamoya syndrome providing a nidus for study of the role of autoimmunity in angiopathy in this population.

RNF213 gene silencing upregulates transforming growth factor β1 expression in bone marrow-derived mesenchymal stem cells and is involved in the onset of Moyamoya disease

Moyamoya disease (MMD) is a chronic and progressive cerebrovascular occlusion disease, the precise etiology of which is poorly understood. Ring finger protein 213 (RNF213) has been previously identified as a susceptibility gene that serves an important role in angiogenesis, where it has been shown to be closely associated with the onset of MMD. Patients with MMD exhibit increased expression levels of various pro-inflammatory molecules and angiogenic factors. Under certain conditions, bone marrow mesenchymal stem cells (BMSCs) have the ability to differentiate to form neuron-like and microglia-like cells. In the present study, a total of 40 MMD patients and 40 healthy individuals were enrolled. ELISA assays revealed that the expression of serum vascular endothelial growth factor (VEGF) and transforming growth factor β1 (TGF-β1) were higher than that in healthy controls. Furthermore, rat BMSCs (rBMSCs) were isolated and cultured using the whole bone marrow adherence method, which were then phenotyped using flow cytometry. Osteogenic and adipogenic differentiation were determined by using Alizarin red and oil red O staining, respectively. RNF213 was knocked-down using a lentivirus-mediated short hairpin RNA system in passage three rBMSCs, and successful transfection of the RNF213 was confirmed by RT-qPCR and fluorescence imaging. The expression levels of VEGF and TGF-β1 in these rBMSCs were measured on days 7 and 14, respectively. The results demonstrated that RNF213 knockdown upregulated TGF-β1 at both protein and mRNA levels, but did not exert any effect on VEGF gene expression. In conclusion, these findings suggested that that RNF213 knockdown may contribute to aberrant TGF-β1 expression via a pathway that remains to be unidentified, indicating that quantitative changes in RNF213 gene expression may serve an important role in the pathogenesis of MMD.

Progression in Moyamoya Disease: Clinical Feature, Neuroimaging Evaluation and Treatment

Moyamoya disease (MMD) is a chronic cerebrovascular disease characterized by progressive stenosis of the arteries of the circle of Willis, with the formation of collateral vascular network at the base of the brain. Its clinical manifestations are complicated. Numerous studies have attempted to clarify the clinical features of MMD, including its epidemiology, genetic characteristics, and pathophysiology. With the development of neuroimaging techniques, various neuroimaging modalities with different advantages have deepened the understanding of MMD in terms of structural, functional, spatial, and temporal dimensions. At present, the main treatment for MMD focuses on neurological protection, cerebral blood flow reconstruction, and neurological rehabilitation, such as pharmacological treatment, surgical revascularization, and cognitive rehabilitation. In this review, we discuss recent progress in understanding the clinical features, in the neuroimaging evaluation and treatment of MMD.

Association of HLA-DQA2 and HLA-B With Moyamoya Disease in the Chinese Han Population

Objective

An HLA imputation was conducted to explore the relationship between HLA and patients with moyamoya disease (MMD) in the Chinese Han population.

Methods

In this study, we performed an association analysis of the major histocompatibility complex region in 2,786 individuals of Chinese Han ancestry (2,031 controls and 755 patients with MMD), through a widely used HLA imputation method.

Results

We identified that the variant rs3129731 (odds ratio [OR] = 1.79, p = 3.69 × 10⁻¹⁶) located between the MTCO3P1 and HLA-DQA2 is a major genetic risk factor for MMD. In addition to this variant, found in the conditional association analysis, we also detected another independent signal, rs1071817 (OR = 0.62, p = 1.20 × 10⁻¹¹), in HLA-B.

Conclusions

Our research suggests that the genetic polymorphism of HLA-DQA2 and HLA-B could be a genetic predisposing factor for MMD in Chinese Han. This may provide some evidence for further HLA-related studies of patients with MMD of Chinese Han ethnicity and indicates that MMD is an immune-related disease.

An analysis of the demographic history of the risk allele R4810K in RNF213 of moyamoya disease

BACKGROUND

Ring finger protein 213 (RNF213) is a susceptibility gene of moyamoya disease (MMD). A previous case-control study and a family analysis demonstrated a strong association of the East Asian-specific variant, R4810K (rs112735431), with MMD. Our aim is to uncover evolutionary history of R4810K in East Asian populations.

METHODS

The RNF213 locus of 24 MMD patients in Japan were sequenced using targeted-capture sequencing. Based on the sequence data, we conducted population genetic analysis and estimated the age of R4810K using coalescent simulation.

RESULTS

The diversity of the RNF213 gene was higher in Africans than non-Africans, which can be explained by bottleneck effect of the out-of-Africa migration. Coalescent simulation showed that the risk variant was born in East Asia 14,500-5100 years ago and came to the Japanese archipelago afterward, probably in the period when the known migration based on archaeological evidences occurred.

CONCLUSIONS

Although clinical data show that the symptoms varies, all sequences harboring the risk allele are almost identical with a small number of exceptions, suggesting the MMD phenotypes are unaffected by the variants of this gene and rather would be more affected by environmental factors.

The Top-100 most cited articles on Moyamoya disease: A bibliometric analysis

OBJECTIVE

Moyamoya disease (MMD) is a progressive steno-occlusive cerebrovascular phenomenon with unknown pathogenesis. Considering the abundance of articles addressing Moyamoya disease, a detailed analysis concerning the publication trends is of paramount importance. The aim of the study is to report the current knowledge of the top-100 most cited articles on Moyamoya disease in the literature.

METHODS

A non-time restricted keyword-based search was performed in June 2020 using the Scopus database. The search keywords included the following: "Moyamoya", "Moyamoya disease", and "Moyamoya syndrome". The search result was used to rank the articles based on their citation count. The top-100 most-cited articles were obtained and classified into seven categories.

RESULTS

A total of 3,543 articles on Moyamoya disease were published between 1955 and 2020. The Top-100 articles were published between 1977 and 2016 with a total of 16,119 citations, per year, and 7.23% rate of self-citation. The 1990s was the most productive decade (N=42). The most contributing country to the list was Japan (N=60). Stroke was the most active journal (N=23). Houkin, K., a Japanese neurosurgeon, was the most prolific author (N=15).

CONCLUSIONS

Moyamoya disease has been extensively investigated in the literature throughout the years. The majority of articles published in the literature were addressing the surgical management and clinical outcome. Authors from neurosurgical backgrounds were the most active contributors to the field of Moyamoya disease.

Disparities in the symptomatic presentation of Moyamoya disease in the United States: A nationwide all-payer analysis

BACKGROUND

Moyamoya disease is a chronic occlusive cerebrovascular disease that can present with either hemorrhagic or ischemic symptoms. The objective of this study was to evaluate whether the symptomatology of Moyamoya disease differs according to patient demographic groups.

METHODS

In this study, we used the Nationwide Inpatient Sample (NIS) to investigate differences in the presentation of Moyamoya disease by age group, gender, and ethnicity from 2012 to 2016. After propensity score matching was utilized to control for overall comorbidity, the matched cohorts for each symptomatology were compared using a Chi-square test with respect to the potential risk factors of interest (i.e. age, sex, ethnicity) in order to generate multivariate reported P-values.

RESULTS

A total of 4,474 patients met inclusion criteria. Patients presenting with ischemic stroke were more likely to be 65 years and older (p < 0.001); patients presenting with intracranial hemorrhage (ICH) were more likely to be 65 years and older (p < 0.001), male (p = 0.027), and Asian (p = 0.007); those presenting with seizure were more likely to be less than 10 years old (p = 0.002) and African American (p < 0.001); and those presenting with headache were more likely to be between 10 and 19 years old (p = 0.008).

CONCLUSIONS

Our findings demonstrate that the distinct presentations of Moyamoya are associated with patient age, gender, and race. This is the largest study of its kind and adds to the collective understanding of this rare but life-threatening condition.

Genetic and Proteomic Contributions to the Pathophysiology of Moyamoya Angiopathy and Related Vascular Diseases

Rationale

This literature review describes the pathophysiological mechanisms of the current classes of proteins, cells, genes, and signaling pathways relevant to moyamoya angiopathy (MA), along with future research directions and implementation of current knowledge in clinical practice.

Objective

This article is intended for physicians diagnosing, treating, and researching MA.

Methods and Results

References were identified using a PubMed/Medline systematic computerized search of the medical literature from January 1, 1957, through August 4, 2020, conducted by the authors, using the key words and various combinations of the key words “moyamoya disease,” “moyamoya syndrome,” “biomarker,” “proteome,” “genetics,” “stroke,” “angiogenesis,” “cerebral arteriopathy,” “pathophysiology,” and “etiology.” Relevant articles and supplemental basic science articles published in English were included. Intimal hyperplasia, medial thinning, irregular elastic lamina, and creation of moyamoya vessels are the end pathologies of many distinct molecular and genetic processes. Currently, 8 primary classes of proteins are implicated in the pathophysiology of MA: gene-mutation products, enzymes, growth factors, transcription factors, adhesion molecules, inflammatory/coagulation peptides, immune-related factors, and novel biomarker candidate proteins. We anticipate that this article will need to be updated in 5 years.

Conclusion

It is increasingly apparent that MA encompasses a variety of distinct pathophysiologic conditions. Continued research into biomarkers, genetics, and signaling pathways associated with MA will improve and refine our understanding of moyamoya’s complex pathophysiology. Future efforts will benefit from multicenter studies, family-based analyses, comparative trials, and close collaboration between the clinical setting and laboratory research.

Clinical Presentation and Stroke Incidence Differ by Moyamoya Etiology

INTRODUCTION

Moyamoya arteriopathy, which can be idiopathic or associated with sickle cell disease, neurofibromatosis, Down syndrome, or cranial radiation therapy, is a progressive cerebral arteriopathy associated with high rates of incident and recurrent stroke. Little is known about how these subgroups differ with respect to clinical presentation, radiographic findings, stroke risk, and functional outcomes.

METHODS

Using ICD codes, we identified children ages 28 days to 18 years treated for moyamoya arteriopathy at our tertiary care center between 2003 and 2019. Demographic, clinical, and radiographic data were extracted from the medical record. The Pediatric Stroke Recurrence and Recovery Questionnaire was administered to consenting participants.

RESULTS

Sixty-nine patients met inclusion criteria (33 idiopathic, 18 sickle cell disease, 11 neurofibromatosis, 6 Down syndrome, 1 cranial radiation therapy). Median follow-up time was 7.7 years; 24 patients had at least 5 years of follow-up data. Frequency of stroke at presentation differed by subgroup (P < .001). Of patients with at least 2 years of follow-up, 33 (55%) experienced stroke. The proportion of patients experiencing stroke differed by subgroup (50% of idiopathic cases, 72% of sickle cell disease, 11% of neurofibromatosis, and 100% of Down syndrome, P = .003). The frequency of bilateral versus unilateral disease (P = .001) and stroke-free survival following presentation (P = .01) also differed by subgroup.

CONCLUSIONS

In this single-center cohort, moyamoya subgroups differed with respect to clinical and radiographic characteristics, with neurofibromatosis-associated moyamoya syndrome having a milder phenotype and Down syndrome-associated moyamoya portending a more aggressive course. These findings need confirmation in a larger, multi-center cohort with longer duration of follow-up.

Familial Risk for Moyamoya Disease Among First-Degree Relatives, Based on a Population-Based Aggregation Study in Korea

BACKGROUND AND PURPOSE

Genetic factors have been known to play a role in the etiology of moyamoya disease (MMD); however, population-level studies quantifying familial risk estimates are unavailable. We aimed to quantify familial incidence and risk for MMD in first-degree relatives (FDR) in the general population of Korea.

METHODS

By using the Korean National Health Insurance database which has complete population coverage and confirmed FDR information, we constructed a cohort of 21 940 795 study subjects constituting 12 million families with blood-related FDR and followed them for a familial occurrence of MMD from 2002 to 2017. Incidence risk ratios were calculated as MMD incidence in individuals with affected FDR compared with those without affected FDR, according to age, sex, and family relationships.

RESULTS

Among total study subjects, there were 22 459 individuals with affected FDR, of whom 712 familial cases developed MMD with an incidence of 21.8/10⁴ person-years. Overall, the familial risk for MMD was 132-fold higher in individuals with versus without affected FDR. Familial risk (incidence risk ratio; incidence/10⁴ person-years) increased with the degree of genetic relatedness, being highest in individuals with an affected twin (1254.1; 230.0), followed by a sibling (212.4; 35.6), then mother (87.7; 14.4) and father (62.5; 10.4). Remarkably, there was no disease concordance between spouses. The risks were age-dependent and were particularly high in younger age groups. Familial risks were similar in males and females, and the risk of disease transmission was higher in same-sex parent-offspring and sibling pairs.

CONCLUSIONS

Our study indicates that genetic predisposition is the predominant driver in MMD pathogenesis, with minimal contribution of environmental factors. These results could be utilized to direct future genetic studies and clinical risk counseling.

Vessel wall MR imaging for the detection of intracranial inflammatory vasculopathies

Intracranial vasculopathies are routinely investigated by lumen-based modalities such as magnetic resonance angiography (MRA), computed tomography angiography (CTA), and digital subtraction angiography (DSA). These techniques are useful to analyze the vessel lumen, allowing to detect vessel stenosis or occlusion. However, the primum movins of the disease, i.e., an abnormal thickening of the vessel wall, remains within the arterial wall. The vasculopathy can moreover be present without always narrowing the lumen or modifying its regularity. Hence, there is a need to detect directly and analyze vessel wall abnormalities. Development of 3D high-resolution black blood sequences for intracranial vessel wall MR imaging (VW-MRI) enabled routine clinical applications not only vasculitis, but also of intracranial atherosclerotic disease (ICAD), intracranial dissections, reversible intracranial dissections, reversible cerebral vasoconstriction syndrome (RCVS), Moyamoya disease, and intracranial aneurysms. This high-resolution intracranial VW- MRI approach is increasingly used on a clinical basis at many centers to solve diagnostic problems, especially in patients with ischemic stroke or intracranial hemorrhage. An expert consensus Guideline from the American Society of Neuroradiology provides recommendations for clinical implementation of intracranial vessel wall MRI. There are several technical aspects needed to be considered when implementing VW-MRI in intracranial vessels, including flow suppression, both in blood and cerebrospinal fluid (CSF), spatial resolution and signal-to-noise ratio (SNR). In this article, we review the technical aspects of VW-MRI, and recommend applications for vascular diseases including non-occlusive intracranial vasculopathies, Moyamoya disease, and identifying culprit plaques. We also give a focus on the utility of VW-MRI for determining stroke etiology in adults and in children and young adults.

Association of Genetic Variants With Moyamoya Disease in 13 000 Individuals: A Meta-Analysis

Background and Purpose- A growing body of evidence indicates genetic components play critical roles in moyamoya disease (MMD). Firm conclusions from studies of this disease have been stymied by small sample sizes and a lack of replicative results. This meta-analysis was conducted to determine whether these genetic polymorphisms are associated with MMD. Methods- PubMed, Google Scholar, Embase, Wanfang, Web of Science, and China National Knowledge Infrastructure databases were used to identify potentially relevant studies published until January 2020. The Review Manager 5.2 and Stata 15.0 software programs were used to perform the statistical analysis. Heterogeneity was assessed using the Cochran Q test and quantified using the I² test. Results- Four thousand seven hundred eleven MMD cases and 8704 controls in 24 studies were included, evaluating 7 polymorphisms in 6 genes. The fixed-effect odds ratios (95% CI) in allelic model of MMP-2 rs243865 were 0.60 (0.41-0.88) (P=0.008). In the country-based subgroup analysis, the fixed-effect odds ratios (95% CI) of RNF213 rs112735431 in allelic model were China, 39.74 (26.63-59.31), Japan, 74.65 (42.79-130.24) and Korea, 50.04 (28.83-86.88; all P<0.00001). In the sensitivity analysis, the fixed-effect odds ratios (95% CI) of allelic and dominant models were the RNF213 rs148731719 variant, 2.17 (1.36-3.48; P=0.001), 2.20 (1.35-3.61; P=0.002), the TIMP-2 rs8179090 variant, 0.33 (0.25-0.43; P<0.00001), 0.88 (0.65-1.21; P=0.440) and the MMP-3 rs3025058 variant, 0.61 (0.47-0.79; P=0.0002), 0.55 (0.41-0.75; P=0.0001), respectively. Conclusions- RNF213 rs112735431 and rs148731719 were positively, and TIMP-2 rs8179090, MMP-2 rs243865, and MMP-3 rs3025058 were inversely associated with MMD using multiple pathophysiologic pathways. Studies in larger population should be conducted to clarify whether and how these variants are associated with MMD.

PHACTR1 is associated with disease progression in Chinese Moyamoya disease

Moyamoya disease (MMD) is a progressive stenosis at the terminal portion of internal carotid artery and frequently occurs in East Asian countries. The etiology of MMD is still largely unknown. We performed a case-control design with whole-exome sequencing analysis on 31 sporadic MMD patients and 10 normal controls with matched age and gender. Patients clinically diagnosed with MMD was determined by digital subtraction angiography (DSA). Twelve predisposing mutations on seven genes associated with the sporadic MMD patients of Chinese ancestry (CCER2, HLA-DRB1, NSD-1, PDGFRB, PHACTR1, POGLUT1, and RNF213) were identified, of which eight single nucleotide variants (SNVs) were deleterious with CADD PHRED scaled score > 15. Sanger sequencing of nine cases with disease progression and 22 stable MMD cases validated that SNV (c.13185159G>T, p.V265L) on PHACTR1 was highly associated with the disease progression of MMD. Finally, we knocked down the expression of PHACTR1 by transfection with siRNA and measured the cell survival of human coronary artery endothelial cell (HCAEC) cells. PHACTR1 silence reduced the cell survival of HCAEC cells under serum starvation cultural condition. Together, these data identify novel predisposing mutations associated with MMD and reveal a requirement for PHACTR1 in mediating cell survival of endothelial cells.

Moyamoya syndrome in a male pseudohermaphrodite patient with congenital adrenal hyperplasia - a rare association. Case report and review of literature

Background and importance: Moyamoya syndrome causes progressive stenosis of intracranial internal carotid arteries and may be associated with genetic disorders like Down's or Turner's syndromes. We treated a male pseudohermaphrodite patient with congenital adrenal hyperplasia (CAH) with clinical and radiological features of moyamoya vasculopathy. To our knowledge, this association has not been reported. Clinical presentation: The 42-year-old patient presented with an intraventicular bleed. Cerebral angiography revealed moyamoya vasculopathy. He was hypertensive and had primary amenorrhea. Secondary sexual characteristics were poorly developed and he had ambiguous genitalia. Breast development was Tanner stage 3. Investigation revealed hypokalemia. With primary amenorrhea, persistent hypokalemia, hypertension and ambiguous genitalia, CAH was considered as a possibility and confirmed on hormone profile. Karyotyping revealed 46XY pattern. Abdominal ultrasound revealed hyperplasia of the adrenal glands, absent uterus and ovaries and ectopic testicles in inguinal canals. He was put on steroids and his blood pressure controlled. Conclusions: To the best of our knowledge we report the first case of moyamoya syndrome occurring in association with CAH.

RATIONALIZATION OF SURGICAL TREATMENT FOR HEMORRHAGIC MOYAMOYA DISEASE: FROM LABORATORY BENCH RESEARCH, BIOMECHANICS TO META-ANALYSIS

Background and purpose: Surgery is recommended as the treatment of choice for hemorrhagic Moyamoya disease (MMD). The rationale of surgery and the choice of procedure are poorly understood. The aim of this paper is to present latest evidence, from cellular, biomechanical and population data, surgical treatment options and their effect on the outcome of hemorrhagic MMD.

Methods: We systematically reviewed the latest evidence from cellular, biomechanical and populational studies including our own meta-analysis for rationalization of management of MMD. We searched major databases from inception to latest articles available till October 2018. All major breakthroughs including basic research to randomized controlled trials (RCTs) and human case–control studies related to hemorrhagic MMD were included. Our meta-analysis was performed in accordance to the standard Cochrane.

Result: Evidence at cellular, biomechanical and RCT levels was presented. For our meta-analysis, we included eight studies, totaling at 632 patients. Our results rationalized the use of surgical methods in support of surgical management of MMD. We showed that surgery in MMD resulted in a significant lower risk of future stroke ([Formula: see text], 95% [Formula: see text]–0.38). Among different surgical methods, the indirect bypass group had a lower risk for sedentary stroke risk reduction compared with the direct bypass group (RR[Formula: see text]=[Formula: see text]3.36, 95% CI[Formula: see text]=[Formula: see text]1.53–7.36). No significant differences were observed in perioperative complications between the two methods.

Conclusion: Surgery remains a mainstay for the management of MMD. We concluded that current evidence in biomechanical and our own meta-analysis is in support of surgery being an effective management of hemorrhagic MMD. We deduced insights into research for early detection, characterization and follow up of patients with MMD.

Multiple Burr-Hole Surgery for the Treatment of Moyamoya Disease and Quasi-Moyamoya Disease in Children: Preliminary Surgical and Imaging Results

OBJECTIVE

Moyamoya disease (MMD) is characterized by a progressive spontaneous occlusion of distal internal carotid arteries and its main branches. It is necessary to promptly diagnose and treat this condition, especially in children, because of the high risk of stroke and consequent severe disability. In this study, we examine the role of multiple burr-hole surgery (MBHS) in the treatment of pediatric patients with MMD and quasi-MMD and the role of perfusion magnetic resonance imaging (MRI) in the surgical indication and during follow-up.

METHODS

We reviewed preoperative, early postoperative, and late postoperative MRI perfusion and digital subtraction angiography images together with clinical and surgical outcomes in 10 children with MMD treated by MBHS.

RESULTS

Fourteen MBHS procedures (6 unilateral, 2 bilateral, and 2 single-setting bilateral) were performed in 10 children. Clinical and radiologic follow-up for all patients ranges from 16 months to 7 years. No ischemic events (transient ischemic attacks or stroke) occurred during the follow-up period. Postoperative digital subtraction angiography showed good revascularization around the burr-hole sites in all patients. The functional efficacy of the surgery was confirmed by dynamic susceptibility contrast perfusion MRI studies in 8 patients.

CONCLUSIONS

Our data underline the good rate of success of MBHS in pediatric MMD and quasi-MMD. This technique results in good collateral revascularization, improved cerebral perfusion and excellent short and long-term symptoms control, with low perioperative risk. Postoperative changes of perfusion parameters and ivy sign MRI finding seem to show a positive correlation and mainly occur in posterior middle cerebral artery territory.

Childhood Moyamoya: Looking Back to the Future

Moyamoya is a chronic, progressive steno-occlusive arteriopathy that typically affects the anterior circulation arteries of the circle of Willis. A network of deep thalamoperforating and lenticulostriate collaterals develop to by-pass the occlusion giving rise to the characteristic angiographic "puff of smoke" appearance. Moyamoya confers a lifelong risk of stroke and neurological demise, with peak age of presentation in childhood ranging between five and 10 years. Moyamoya disease refers to patients who do not have a comorbid condition, whereas moyamoya syndrome refers to patients in whom moyamoya occurs in association with an acquired or inherited disorder such as sickle cell disease, neurofibromatosis type-1 or trisomy 21. The incidence of moyamoya disease and moyamoya syndrome demonstrates geographic and ethnic variation, with a predominance of moyamoya disease in East-Asian populations. Antiplatelet therapy and surgical revascularization procedures are the mainstay of management, as there are no available treatments to slow the progression of the arteriopathy. Future research is required to address the major gaps that remain in our understanding of the pathologic basis, optimal timing for surgery, and determinants of outcome in this high-stroke risk condition of childhood.

Epidemiology, diagnosis and treatment of moyamoya disease

Moyamoya disease (MMD) is a type of chronic cerebrovascular occlusion disease, which frequently occurs in East Asian populations, including pediatric and adult patients, and may lead to ischemic or hemorrhagic stroke, headache, epilepsy or transient ischemic attack. To date, the underlying mechanisms of MMD have remained to be fully elucidated, but certain studies have indicated that genetic factors may be an important component of its development. Cerebral angiography is the best approach for diagnosing MMD. However, with technological advances, non-invasive techniques are increasingly used to accurately evaluate MMD. MMD is commonly treated via surgery, and an increasing number of patients are benefitting from the intra- and extra-cranial revascularization. The present article provides a comprehensive review of MMD on the basis of previous research.

RNF213 Variant Diversity Predisposes Distinct Populations to Dissimilar Cerebrovascular Diseases

In recent years, the ring finger protein 213 gene (RNF213) has gradually attracted attention, mainly because it has been found that RNF213 c.14429 G>A is associated with moyamoya disease (MMD) in East Asian populations. Recent studies have revealed that RFN213 is not only associated with MMD but is also connected with intracranial major artery stenosis/occlusion (ICASO) and intracranial aneurysm (IA). However, only the relationship between RNF213 c.14429 G>A and ICASO has been confirmed, and whether RNF213 has other mutations related to ICASO remains unclear. RNF213 and IA are currently only confirmed to be correlated in French-Canadian Population and no correlation has been found in the Japanese population. This review summarizes the advances in the associations between RNF213 and different cerebrovascular diseases and highlights that variant diversity of RNF213 may predispose distinct populations to dissimilar cerebrovascular diseases.

Whole exome sequencing identifies MRVI1 as a susceptibility gene for moyamoya syndrome in neurofibromatosis type 1

Background and purpose

Moyamoya angiopathy is a progressive cerebral vasculopathy. The p.R4810K substitution in RNF213 has previously been linked to moyamoya disease in Asian populations. When associated with other medical conditions, such as neurofibromatosis type 1, this vasculopathy is frequently reported as moyamoya syndrome. Intriguingly, most cases of moyamoya-complicated neurofibromatosis type 1 have been described in Caucasians, inverting the population ratio observed in Asians, although prevalence of neurofibromatosis type 1 is constant worldwide. Our aim was to investigate whether, among Caucasians, additive genetic factors may contribute to the occurrence of moyamoya in neurofibromatosis type 1.

Methods

Whole exome sequencing was carried out on an Italian family with moyamoya-complicated neurofibromatosis type 1 to identify putative genetic modifiers independent of the NF1 locus and potentially involved in moyamoya pathogenesis. Results were validated in an unrelated family of German ancestry.

Results

We identified the p.P186S substitution (rs35857561) in MRVI1 that segregated with moyamoya syndrome in both the Italian and German family.

Conclusions

The rs35857561 polymorphism in MRVI1 may be a genetic susceptibility factor for moyamoya in European patients with neurofibromatosis type 1. MRVI1 is a functional partner of ITPR1, PRKG1 and GUCY1A3, which are involved in response to nitric oxide. Mutations in GUCY1A3 have been recently linked to a recessive syndromic form of moyamoya with esophageal achalasia.

Novel Susceptibility Loci for Moyamoya Disease Revealed by a Genome-Wide Association Study

Background and Purpose—

Moyamoya disease (MMD) is a rare cerebral vasculopathy characterized by bilateral internal carotid artery stenosis and often leads to stroke in children or young adults. Although familial inheritance is well recognized, the genetic basis of MMD remains poorly understood.

Methods—

A 2-stage genome-wide association study was conducted involving 1492 cases and 5084 controls. In the discovery stage, logistic regression was used to test associations, and imputation was conducted based on genotyped single-nucleotide polymorphisms (SNPs). In the validation stage, the top significant SNPs were again genotyped in an independent cohort. Fixed-effects inverse variance-weighted meta-analysis was used in the combined discovery and validation samples. Furthermore, association analysis was conducted in subgroups using patient clinical data.

Results—

The study identified 10 novel risk loci with genome-wide significance ( P <5×10 −8 ) and confirmed a previously reported locus on 17q25. No significant SNP showed evidence of heterogeneity between the 2 stages. Cumulatively, these SNPs explained 14.76% of disease risk variance—a substantial proportion of the 39.02% of risk variance explained by all genome-wide genotyped SNPs. One SNP, rs9916351 in RNF213 ( P combined =4.57×10 −54 ; odds ratio, 1.96), showed a stronger genetic effect on early-onset than late-onset MMD ( P =0.003). Two novel SNPs in genes regulating homocysteine metabolism, rs9651118 in MTHFR ( P combined =2.49×10 −19 ; odds ratio, 0.65) and rs117353193 in TCN2 ( P combined =6.15×10 −13 ; odds ratio, 1.43), were associated with high-serum homocysteine in MMD cases. Additionally, another SNP associated with MMD (rs2107595 in HDAC9 ; P combined =1.49×10 −29 ; odds ratio, 1.64) was previously implicated in large-vessel disease. Tissue enrichment analysis showed that the genes of associated loci were highly expressed in the immune system (false discovery rate, <0.05).

Conclusions—

This study identifies several novel susceptibility genes for MMD. The association with homocysteine metabolism and the immune system enrichment of susceptibility gene expression suggest that therapeutic interventions targeting these pathways may be effective approaches for MMD treatment.

The Role of RNF213 4810G>A and 4950G>A Variants in Patients with Moyamoya Disease in Korea

Although a founder variant of RNF213 4810G>A is a major genetic risk factor for moyamoya disease (MMD) in East Asians, the frequency and disease susceptibility of RNF213 variants remain largely unknown. This study investigated the mutation analysis of RNF213 (4448, 4810, 4863, and 4950) between Korean MMD and healthy controls. We performed a polymerase chain reaction-restriction fragment length polymorphism analysis. To identify the association between RNF213 gene polymorphisms and MMD disease, we performed statistical analyses such as multivariable logistic regression and Fisher’s exact test. Genetic data from 117 MMD patients were analyzed and compared with 253 healthy controls. We assessed and compared single nucleotide polymorphisms of RNF213 (4448, 4810, 4863, and 4950) between MMD and control groups. We performed genome-wide association studies to investigate the genetic pathophysiology of MMD. Among the RNF213 variants (4448G>A, 4810G>A, 4863G>A, and 4950G>A), RNF213 4810G>A and 4950G>A variants were more frequent in MMD patients. In a subgroup analysis, the RNF213 4810G>A was more frequent in moyamoya disease, and the comparison with GG+AA genotype was also significantly different in moyamoya patients. These results confirm that RNF213 4810G>A and RNF213 4950G>A were more frequent in MMD patients. We have confirmed that RNF213 4810G>A and 4950G>A are strongly associated with Korean MMD in children and adults as well as for the ischemic and hemorrhagic types.

Moyamoya Disease in Children: Results From the International Pediatric Stroke Study

This study aimed to describe children with moyamoya disease from an international multicenter stroke database, and explore risk factors for stroke recurrence. We reviewed data of children >28-days old with moyamoya disease enrolled in the International Pediatric Stroke Study from January 2003 to March 2013. A total of 174 children from 32 sites and 14 countries had moyamoya disease; median age 7.4 years, 49% male. Of these, 90% presented with ischemic stroke, 7.5% with transient ischemic attack, and 2.5% with hemorrhagic stroke. One-third of patients had moyamoya syndrome. Stroke recurrence was 20% over median follow-up of 13 months; 9% had multiple recurrences. Children treated with surgical revascularization were less likely to have stroke recurrence ( P = .046). Moyamoya disease accounted for 8% of arterial strokes in this international pediatric stroke registry. One-third of pediatric patients with moyamoya disease have an underlying syndromic condition. Surgical revascularization is effective at reducing the incidence of stroke recurrence.

Frequency and significance of rare RNF213 variants in patients with adult moyamoya disease

Purpose

Moyamoya disease (MMD) is a rare cerebrovascular disorder characterized by stenosis of the internal carotid arteries with compensatory development of collateral vessels. Although a founder variant of RNF213, p.Arg4810Lys (c.14429G>A, rs112735431), is a major genetic risk factor for MMD in East Asians, the frequency and disease susceptibility of other variants in this gene remain largely unknown. In the present study, we investigated the association of RNF213 variants with MMD in Korean patients and population controls.

Methods

For all RNF213 variants listed in the Human Gene Mutation Database (HGMD) as disease-causing or likely disease-causing mutations for MMD, genotyping was performed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Genetic data from 264 adult patients with MMD were analyzed and compared with two control populations comprised of 622 and 1,100 Korean individuals, respectively.

Results

Among the 30 RNF213 variants that were listed in the HGMD, p.Arg4810Lys was identified in 67.4% (178/264) of patients with MMD and showed a significantly higher allele frequency than in the controls, giving an odds ratio of 63.29 (95% confidence interval, 33.11–120.98) for the 622 controls and 48.55 (95% confidence interval, 31.00–76.03) for the 1100 controls. One additional variant, p.Ala5021Val (c.15062C>T, rs138130613), was identified in 0.8% (2/264) of patients; however, the allele frequencies were not significantly different from those in the controls.

Conclusions

These results suggest that, in our cohort of Korean patients, the p.Arg4810Lys is the only variant that is strongly associated with MMD among the 30 RNF213 variants listed in the HGMD.

De novo mutations in CBL causing early-onset paediatric moyamoya angiopathy

BACKGROUND

Moyamoya angiopathy (MMA) is characterised by a progressive stenosis of the terminal part of the internal carotid arteries and the development of abnormal collateral deep vessels. Its pathophysiology is unknown. MMA can be the sole manifestation of the disease (moyamoya disease) or be associated with various conditions (moyamoya syndrome) including some Mendelian diseases. We aimed to investigate the genetic basis of moyamoya using a whole exome sequencing (WES) approach conducted in sporadic cases without any overt symptom suggestive of a known Mendelian moyamoya syndrome.

METHODS

A WES was performed in four unrelated early-onset moyamoya sporadic cases and their parents (trios). Exome data were analysed under dominant de novo, autosomal recessive and X-linked hypotheses. A panel of 17 additional sporadic cases with early-onset moyamoya was available for mutation recurrence analysis.

RESULTS

We identified two germline de novo mutations in CBL in two out of the four trio probands, two girls presenting with an infancy-onset severe MMA. Both mutations were predicted to alter the ubiquitin ligase activity of the CBL protein that acts as a negative regulator of the RAS pathway. These two germline CBL mutations have previously been described in association with a developmental Noonan-like syndrome and susceptibility to juvenile myelomonocytic leukaemia (JMML). Notably, the two mutated girls never developed JMML and presented only subtle signs of RASopathy that did not lead to evoke this diagnosis during follow-up.

CONCLUSIONS

These data suggest that CBL gene screening should be considered in early-onset moyamoya, even in the absence of obvious signs of RASopathy.

Tuberous sclerosis complex and polycystic kidney disease contiguous gene syndrome with Moyamoya disease

Tuberous sclerosis complex (TSC) and autosomal dominant polycystic kidney disease (ADPKD) are two diseases sharing close genetic loci on chromosome 16. Due to contiguous gene syndrome, also known as contiguous gene deletion syndrome, the proximity of TSC2 and PKD1 genes increases the risk of co-deletion resulting in a shared clinical presentation. Furthermore, Moyamoya disease (MMD) is a rare vaso-occlusive disease in the circle of Willis. We present the first case of TSC2/PKD1 contiguous gene syndrome in a patient with MMD along with detailed histopathologic, radiologic, and cytogenetic analyses. We also highlight the clinical presentation and surgical complications in this case.

The Susceptibility Pathogenesis of Moyamoya Disease

Moyamoya disease (MMD) is a cerebrovascular disease characterized by progressive stenosis of the intracranial internal carotid arteries and their proximal branches. Epidemiologically, MMD is more prevalent in East Asia than any other region worldwide, and has been estimated at 0.94 per 100,000 in the Japanese and 0.43 per 100,000 in the Chinese population. The etiology of this rare disease, however, remains unknown. Regarding biomarkers, MMD is characterized by an increased expression of angiogenic factors and proinflammatory molecules such as vascular endothelial growth factors and matrix metalloproteinase-9, which may partly explain its clinical manifestations of the pathologic angiogenesis, spontaneous hemorrhage, and greater incidence of cerebral hyperperfusion after revascularization surgery. More recently, blockade of these proinflammatory molecules during the perioperative period is attempted to reduce the potential risk of surgical complications, including cerebral hyperperfusion syndrome. Recent genome-wide and locus-specific association studies identified RNF213 as an important susceptibility gene of MMD among the East Asian population. The exact mechanism by which the RNF213 abnormality relates to MMD remains unknown, whereas recently identified RNF213 encodes a 591-kDa protein containing enzymatically active P-loop ATPase and ubiquitin ligase domains and is involved in proper vascular development in zebrafish provide new insight for the pathogenesis of this rare entity. In this review article, we focused on the genetics and biomarkers of MMD and sought to discuss their clinical implication.

Etiology and pathogenesis of Moyamoya Disease: An update on disease prevalence

Moyamoya disease is a chronic cerebrovascular occlusive disease that is characterized by progressive stenosis of the terminal portion of the internal carotid artery and its main branches. The occurrence of Moyamoya disease is related to immune, genetic, and other factors. Though the research of Moyamoya disease has made great strides in the past 60 years, the etiology and pathogenesis are largely unknown. This review will focus on the genetic pathogenic and inflammation factors of Moyamoya disease.

RNF213 as the major susceptibility gene for Chinese patients with moyamoya disease and its clinical relevance

OBJECTIVE Moyamoya disease (MMD) is a rare, genetically heterogeneous cerebrovascular disease. The authors conducted a genetic study of really interesting new gene (RING) finger protein 213 ( RNF213); actin alpha 2 ( ACTA2); BRCA1/BRCA2-containing complex subunit 3 ( BRCC3); and guanylate cyclase 1, soluble, alpha 3 ( GUCY1A3) as well as a clinical phenotype analysis in Chinese MMD patients to determine whether genetic differences are responsible for the different clinical features that appear in MMD in different ethnicities. METHODS A panel was designed to identify disease-causing mutations in MMD genes and those involved in related disorders ( RNF213, ACTA2, BRCC3, and GUCY1A3). The panel was used to detect disease-causing mutations in 255 Chinese MMD patients. Genotype and allele frequencies were compared between patients and 300 controls. A mutation segregation analysis was performed in 34 families, and genotype-phenotype correlations were made. RESULTS Twenty-seven rare missense variants of RNF213 were identified and were not found in controls. Among them, p.R4810K was identified in 31.4% of patients (80 of 255) with MMD. Significantly higher frequencies of the A allele and G/A genotype of p.R4810K were observed in MMD patients compared with controls (χ² = 104.166, p < 0.000). Twenty-five rare variants were identified in 10.6% of patients (27 of 255) without p.R4810K variants. Segregation analysis supported an association between MMD and 3 variants. No possible disease-causing mutations were identified in ACTA2, BRCC3, or GUCY1A3. Compared with patients without the rare variants in RNF213, the p.R4810K heterozygous patients were younger at diagnosis (25 vs 29 years old, p = 0.049) and had more familial cases (24% vs 4.4%, p = 0.000), ischemic cases (81.3% vs 67.5%, p = 0.037), and involvement of the posterior cerebral artery (52% vs 32.5%, p = 0.007). CONCLUSIONS RNF213 is the major susceptibility gene in Chinese MMD patients. The spectrum of rare variants identified in Chinese MMD patients was diverse. Compared to patients without the rare variants in RNF213, the p.R4810K heterozygous patients exhibited different clinical features.

Significance of cyclooxygenase-2 elevation in middle cerebral artery for patients with hemorrhagic moyamoya disease

The etiology and pathogenesis of moyamoya disease (MMD) remain elusive. Some inflammatory proteins, such as cyclooxygenase (COX)-2, are believed to be implicated in the development of MMD. So far, the relationship between COX-2 and MMD is poorly understood and reports on the intracranial vessels of MMD patients are scanty. In this study, tiny pieces of middle cerebral artery (MCA) and superficial temporal artery (STA) from 13 MMD patients were surgically harvested. The MCA and STA samples from 5 control patients were also collected by using the same technique. The expression of COX-2 was immunohistochemically detected and the average absorbance (A) of positively-stained areas was measured. High-level COX-2 expression was found in all layers of the MCA samples from all 5 hemorrhagic MMD patients, while positive but weak expression of COX-2 was observed only in the endothelial layer of the MCA samples from most ischemic MMD patients (6/8, 75%). The average A values of COX-2 in the hemorrhagic MMD patients were substantially higher than those in their ischemic counterparts (t=4.632, P=0.001). There was no significant difference in the COX-2 expression among the "gender" groups, or "radiographic grade" groups, or "lesion location" groups (P>0.05 for all). The COX-2 expression was detected neither in the MCA samples from the controls nor in all STA specimens. Our results suggested that COX-2 was up-regulated in the MCA of MMD patients, especially in hemorrhagic MMD patients. We are led to speculate that COX-2 may be involved in the pathogenesis of MMD and even contribute to the hemorrhagic stroke of MMD patients.

The Pathophysiology of Moyamoya Disease: An Update

Moyamoya disease (MMD) is a unique cerebrovascular disease characterized by the progressive stenosis of large intracranial arteries and a hazy network of basal collaterals called moyamoya vessels. Because the etiology of MMD is unknown, its diagnosis is based on characteristic angiographic findings. Re-vascularization techniques (e.g., bypass surgery) are used to restore perfusion, and are the primary treatment for MMD. There is no specific treatment to prevent MMD progression. This review summarizes the recent advances in MMD pathophysiology, including the genetic and circulating factors related to disease development. Genetic and environmental factors may play important roles in the development of the vascular stenosis and aberrant angiogenesis in complex ways. These factors include the related changes in circulating endothelial/smooth muscle progenitor cells, cytokines related to vascular remodeling and angiogenesis, and endothelium, such as caveolin which is a plasma membrane protein. With a better understanding of MMD pathophysiology, nonsurgical approaches targeting MMD pathogenesis may be available to stop or slow the progression of this disease. The possible strategies include targeting growth factors, retinoic acid, caveolin-1, and stem cells.

Diagnosing moyamoya syndrome using ultrasound - a case report

Background

Moyamoya syndrome is a vasculopathy characterised by progressive occlusion of the cerebral arteries resulting in the development of abnormal collateral circulation. To diagnose this syndrome, imaging of the cerebral arteries is required including CT- or MR-angiography and conventional angiography. We present a case of moyamoya disease with typical findings detected in the sonography. The diagnosis was suspected after reviewing the initial ultrasound images of the cerebral arteries with evidence for obliterated intracranial arteries and the detection of an existing collateral circulation network.

Case presentation

A 62 years old male patient presented in the hospital’s emergency department with symptoms indicating a subacute cerebrovascular event. Immediate sonographic studies showed a right-sided pulsatile Doppler-signal in the common and internal carotid arteries, suggestive of distal stenoses. In addition, the transcranial examination indicated obliteration of both middle cerebral arteries. Numerous arterial vessels suggestive of leptomeningeal collateral arteries revealed a strong arterial leptomeningeal flow. At this stage of the diagnostic work-up, the collateral circulation network, characteristic of moyamoya disease, was indicated by sonography. Moyamoya syndrome was verified by conventional angiography. The aetiological work remained empty, so the diagnosis of moyamoya disease was established.

Conclusion

Our case report indicates that sonography can be a useful tool for detecting the vaculopathy in moyamoya syndrome. In case routine procedures, such as the CT- or MR-angiography, with evidence for obliterated intracerebral arteries, ultrasound studies might provide important information regarding an existing collateral network in the scope of a moyamoya syndrome.

A new horizon of moyamoya disease and associated health risks explored through RNF213

The cerebrovascular disorder moyamoya disease (MMD) was first described in 1957 in Japan, and is typically considered to be an Asian-specific disease. However, it is globally recognized as one of the major causes of childhood stroke. Although several monogenic diseases are known to be complicated by Moyamoya angiopathy, the ring finger protein 213 gene (RNF213) was identified as a susceptibility gene for MMD. RNF213 is unusual, because (1) it induces MMD with no other recognizable phenotypes, (2) the RNF213 p.R4810K variant is an Asian founder mutation common to Japanese, Korean and Chinese with carrier rates of 0.5–2 % of the general population but a low penetrance, and (3) it encodes a relatively largest proteins with a dual AAA+ ATPase and E3 Ligase activities. In this review, we focus on the genetics and genetic epidemiology of RNF213, the pathology of RNF213 R4810K, and the molecular functions of RNF213, and also address the public health contributions to current unresolved issues of MMD. We also emphasize the importance of a more updated definition for MMD, of qualified cohort studies based on genetic epidemiology and an awareness of the ethical issues associated with genetic testing of carriers.

Disease Variant Landscape of a Large Multiethnic Population of Moyamoya Patients by Exome Sequencing

Moyamoya disease (MMD) is a rare disorder characterized by cerebrovascular occlusion and development of hemorrhage-prone collateral vessels. Approximately 10-12% of cases are familial, with a presumed low penetrance autosomal dominant pattern of inheritance. Diagnosis commonly occurs only after clinical presentation. The recent identification of the RNF213 founder mutation (p.R4810K) in the Asian population has made a significant contribution, but the etiology of this disease remains unclear. To further develop the variant landscape of MMD, we performed high-depth whole exome sequencing of 125 unrelated, predominantly nonfamilial, ethnically diverse MMD patients in parallel with 125 internally sequenced, matched controls using the same exome and analysis platform. Three subpopulations were established: Asian, Caucasian, and non-RNF213 founder mutation cases. We provided additional support for the previously observed RNF213 founder mutation (p.R4810K) in Asian cases (P = 6.01×10(-5)) that was enriched among East Asians compared to Southeast Asian and Pacific Islander cases (P = 9.52×10(-4)) and was absent in all Caucasian cases. The most enriched variant in Caucasian (P = 7.93×10(-4)) and non-RNF213 founder mutation (P = 1.51×10(-3)) cases was ZXDC (p.P562L), a gene involved in MHC Class II activation. Collapsing variant methodology ranked OBSCN, a gene involved in myofibrillogenesis, as most enriched in Caucasian (P = 1.07×10(-4)) and non-RNF213 founder mutation cases (P = 5.31×10(-5)). These findings further support the East Asian origins of the RNF213 (p.R4810K) variant and more fully describe the genetic landscape of multiethnic MMD, revealing novel, alternative candidate variants and genes that may be important in MMD etiology and diagnosis.

Moyamoya angiopathy - Is there a Western phenotype?

Moyamoya disease (MMD) is a chronic cerebrovascular disease involving progressive bilateral stenosis of the intracranial segments of the internal carotid arteries. It results in the development of a rich, but friable collateral supply, prone to rupture. The disease is well described in Japanese literature and was originally thought to be a predozminantly Eastern disease. However, the recent literature describes a Western phenotype that may present with a different clinical course. This review aims to describe the variations in the epidemiology of the MMD between Eastern and Western populations, the possible reasons for them and highlight their implications for clinical practise and future research.

Importance of RNF213 polymorphism on clinical features and long-term outcome in moyamoya disease

OBJECT Moyamoya disease (MMD) is an idiopathic cerebrovascular occlusive disorder prevalent in East Asia. In the pathogenesis of MMD, the important role of genetic factors is being elucidated, and RNF213 has recently been identified as a susceptibility gene for MMD. The aim of this retrospective study was to investigate the RNF213 genotype in patients with MMD and to determine their genotype-phenotype associations. METHODS The study involved 165 Korean MMD patients from 155 unrelated families who were diagnosed with MMD at a single center from 1995 to 2013. Their demographic, radiological, and clinical findings were evaluated. Direct sequencing of the major RNF213 single nucleotide polymorphisms was performed. The association of the common RNF213 variant with MMD risk was evaluated using historical controls for comparison. Correlations between RNF213 genotype and phenotype were statistically analyzed. RESULTS The c.14429G>A (p.R4810K) variant was identified in 125 (75.8%) of 165 MMD patients. Most patients (112) were heterozygous, and 13 patients had 2 copies of the c.14429G>A variant. A novel heterozygous variant, c.12086A>G (p.Q4029R), was found in 1 additional patient. The minor allele frequency of the c.14429G>A variant was significantly higher in the MMD group (138 [41.8%] of 330 patients) than in the control group (8 [1.36%] of 588 subjects; p < 0.001). The c.14429G>A (p.R4810K) variant significantly increased the risk of MMD in Korean patients, with an OR of 52.11 (p < 0.001) compared with controls. Moreover, c.14429G>A (p.R4810K) genotypes occurred more frequently in patients with a family history of MMD. The homozygous variant was highly associated with early-onset MMD (age at onset < 5 years), cerebral infarction at diagnosis, and cognitive impairment in long-term outcome. CONCLUSIONS The findings indicate that the c.14429G>A (p.R4810K) allele of RNF213 is strongly associated with Korean patients with MMD. The homozygous c.14429G>A (p.R4810K) variant is particularly related to early-onset MMD, severe symptomatic manifestations at diagnosis, and poor prognosis. This genotypic variant may be a useful biomarker for early-onset MMD or unstable MMD with cerebral infarction, which requires early diagnosis and revascularization treatment.

Moyamoya disease susceptibility gene RNF213 links inflammatory and angiogenic signals in endothelial cells

Moyamoya disease (MMD) is a cerebrovascular disorder characterized by occlusive lesions of the circle of Willis. To date, both environmental and genetic factors have been implicated for pathogenesis of MMD. Allelic variations in RNF213 are known to confer the risk of MMD; however, functional roles of RNF213 remain to be largely elusive. We herein report that pro-inflammatory cytokines, IFNG and TNFA, synergistically activated transcription of RNF213 both in vitro and in vivo. Using various chemical inhibitors, we found that AKT and PKR pathways contributed to the transcriptional activation of RNF213. Transcriptome-wide analysis and subsequent validation with quantitative PCR supported that endogenous expression of cell cycle-promoting genes were significantly decreased with knockdown of RNF213 in cultured endothelial cells. Consistently, these cells showed less proliferative and less angiogenic profiles. Chemical inhibitors for AKT (LY294002) and PKR (C16) disrupted their angiogenic potentials, suggesting that RNF213 and its upstream pathways cooperatively organize the process of angiogenesis. Furthermore, RNF213 down-regulated expressions of matrix metalloproteases in endothelial cells, but not in fibroblasts or other cell types. Altogether, our data illustrate that RNF213 plays unique roles in endothelial cells for proper gene expressions in response to inflammatory signals from environments.