Moyamoya disease in Southeast Asians: genetic and autopsy data, new cases, systematic review, and meta-analysis of all patients from the literature.

BACKGROUND: Moyamoya disease (MMD) is a rare disorder causing ischemic and hemorrhagic juvenile stroke. It is associated with the founder susceptibility variant p.R4810K in the RNF213 gene in East Asia. Our aim was to enhance understanding of MMD in so far poorly characterized Southeast Asians and exploring differences with Caucasian Europeans. METHODS: By retrospective analysis of medical records and systematic database search on PubMed for all published cases, we identified Southeast Asian patients with MMD. We extracted and pooled proportions using fixed-effects models. Our own cohort was tested for the East Asian RNF213 founder variant p.R4810K. One of our Southeast Asian patients underwent post-mortem histopathological examination. RESULTS: The study cohort comprised 32 Southeast Asians. Mean age at onset in the entire cohort was 32.5 ± 20.3 years (n = 24), 43.4 ± 8.7 years in patients admitted to our center (n = 11), and 23.4 ± 22.4 years in patients from the international literature (n = 13). Female-to-male ratio was 1.6:1. MMD predominantly affected bilateral anterior intracranial vessels. Cerebral ischemia outnumbered transient ischemic attacks (TIAs) and intracranial hemorrhage. TIAs, arterial hypertension and obesity were significantly less frequent in Southeast Asian patients compared to Caucasian Europeans. p.R4810K was absent in all examined Southeast Asians despite of typical histopathological signs of MMD in one autopsy case. CONCLUSION: Clinical and histopathological manifestations of MMD in Southeast Asians are similar to those in Caucasian Europeans. The genotype of MMD in Southeast Asians differs from that of most East Asian patients.

First Report: Rare RNF213 Variant Associated with Familial Moyamoya Disease in an African American Family.

OBJECTIVE: To investigate potential genetic susceptibility for moyamoya disease (MMD) in an African American family. MATERIALS AND METHODS: Neurovascular imaging and analyses of MMD susceptibility genes RNF213 and/or ACTA2 in a young proband with MMD and two first-degree relatives. RESULTS: The proband presented with pseudobulbar affect and chorea, then had a right hemispheric ischaemic stroke and rapidly fatal course. One relative had a mild haemorrhagic thalamic stroke and clinically silent ischaemic infarct. Despite evidence of slowly progressive disease, he remained clinically stable. Another relative was neurologically intact with normal cerebrovascular imaging to date. All three have the rare R4131C (p.Arg4131Cys or p.R4131C, c.12391C>T) variant of the RNF213 gene. They are the first Black people and only the 5th family worldwide known to harbour this variant. MMD was confirmed in both of the patients with neurological events. CONCLUSIONS: Our report provides compelling evidence that MMD is a clinically complex, heritable genetic disease. It supports the probable pathogenicity of R4131C. Furthermore, it illustrates the wide phenotypic spectrum of R4131C, from asymptomatic carrier to late presenting, mild disease to catastrophic, rapidly fatal childhood disease. To our knowledge, this is also the first report of heritable MMD in a Black family. Finally, this study highlights the importance of racially and ethnically diverse participants in biomedical research.

Role of the RNF213 Variant in Vascular Outcomes in Patients With Intracranial Atherosclerosis.

Background The RNF213 (ring finger protein 213 gene) variant R4810K is a susceptibility allele not only for Moyamoya disease (MMD) but also for intracranial atherosclerosis (ICAS) in East Asian populations. We hypothesized that this variant would affect the distribution of ICAS and recurrence of cerebrovascular events. Methods and Results We conducted a prospective study of patients with ICAS and MMD using high-resolution magnetic resonance imaging and RNF213 R4810K genotyping. Patients were included in the ICAS group when relevant plaques existed on high-resolution magnetic resonance imagingand in the MMD group when they carried the variant and high-resolution magnetic resonance imaging showed no plaques but characteristic features of MMD. We compared clinical and neuroimaging features of patients with ICAS-RNF213+ with patients with ICAS-RNF213- and of patients with MMD. Of 477 patients, 238 patients were in the ICAS group and 239 were in the MMD group. Among patients with ICAS, 79 patients (33.2%) were in the ICAS-RNF213+ group and 159 (66.8%) in the ICAS-RNF213- group. Tandem lesions were significantly more common in the ICAS-RNF213+ group than in the ICAS-RNF213- group (40.3% versus 72.2%, P<0.001), and their distributions were similar between the ICAS-RNF213+ and MMD groups. The presence of the R4810K variant (hazard ratio [HR], 3.203; 95% CI, 1.149-9.459; P=0.026) and tandem lesions (≥3) (HR, 8.315; 95% CI, 1.930-39.607; P=0.005) were independently associated with recurrent cerebrovascular events. Conclusions Patients with ICAS carrying the RNF213 R4810K variant showed clinical and imaging features distinct from patients with ICAS without the variant, suggesting that the R4810K variant plays a role in intracranial atherosclerosis in East Asian patients.

Moyamoya vasculopathy shows a genetic mutational gradient decreasing from East to West.

BACKGROUND: Moyamoya disease (MMD) is a chronic, occlusive cerebrovascular disease characterized by bilateral steno-occlusive changes at the terminal portion of the internal carotid arteries and an abnormal vascular network at the base of the brain determining stroke in children. Patients with a similar vasculopathy and associated conditions are affected by the moyamoya syndrome (MMS). Most of the studies focused on MMD were carried out on East-Asian population. Ring Finger 213 (RNF213) has been identified as the strongest susceptibility gene for MMD in East-Asian people. Overall, 74.5% of the East-Asian patients carry the founder variant p.Arg4810Lys of RNF213 never reported in Caucasians. A different genetic landscape among the diverse ethnic populations seems to exist. METHODS: We sequenced the coding sequence region of RNF213, TGFB1 and PDGFRB in 21 ethnically homogeneous Italian children with moyamoya; comprehensive sequencing data are available from parents of eight of them. The analyses were carried out by NGS on Thermo-fisher PGM platform. We also performed a comprehensive review of the literature about the variations of these three genes in Caucasian patients. RESULTS: Several new variants of RNF213 gene were detected, in particular, two new pathogenic mutations on RNF213 (p.Trp4677Leu and p.Cys4017Ser) were identified in one MMS case and in one MMD case, respectively. Moreover, in a MMS case a new probably causing disease mutation p.Pro1063Thr of PDGFRB was detected. CONCLUSIONS: The genetic susceptibility of Asian moyamoya vasculopathy seems to differ from the Caucasian disease. No additional differences seem to exist between MMD and MMS.

Differences in the Genotype Frequency of the RNF213 Variant in Patients with Familial Moyamoya Disease in Kyushu, Japan.

The p.R4810K (rs11273543, c.14429G > A) variant of the RNF213 gene is associated with increased risk of Moyamoya disease (MMD), which is an idiopathic progressive intracranial vascular steno-occlusive disease, in Asian populations. Numerous variant association studies for this MMD variant have been performed in Japan to date. Since another genetic study that utilized approximately 140,000 single nucleotide polymor (SNPs) has indicated that there still are genetic differences among mainland Japanese, there is a possibility that the variant distribution in patients with MMD and normal individuals varies between different Japanese regions. Additionally, the majority of variant association studies have used Sanger sequencing, which is labor-intensive, time-consuming, and costly. In this study, we analyzed the frequency of the variant genotype in patients with MMD and normal individuals in Kyushu using pyrosequencing, which is an accurate, cost-effective, and automated method. We found differences in the genotype frequencies in familial patients from Kyushu and normal populations in Tohoku compared with west Japan, which suggested that there were differences in the frequency of the variant among different regions in Japan.

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.

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

Moyamoya angiopathy (MMA) is a cerebral angiopathy affecting the terminal part of internal carotid arteries. Its prevalence is 10 times higher in Japan and Korea than in Europe. In East Asian countries, moyamoya is strongly associated to the R4810K variant in the RNF213 gene that encodes for a protein containing a RING-finger and two AAA+ domains. This variant has never been detected in Caucasian MMA patients, but several rare RNF213 variants have been reported in Caucasian cases. Using a collapsing test based on exome data from 68 European MMA probands and 573 ethnically matched controls, we showed a significant association between rare missense RNF213 variants and MMA in European patients (odds ratio (OR)=2.24, 95% confidence interval (CI)=(1.19-4.11), P=0.01). Variants specific to cases had higher pathogenicity predictive scores (median of 24.2 in cases versus 9.4 in controls, P=0.029) and preferentially clustered in a C-terminal hotspot encompassing the RING-finger domain of RNF213 (P<10-3). This association was even stronger when restricting the analysis to childhood-onset and familial cases (OR=4.54, 95% CI=(1.80-11.34), P=1.1 × 10-3). All clinically affected relatives who were genotyped were carriers. However, the need for additional factors to develop MMA is strongly suggested by the fact that only 25% of mutation carrier relatives were clinically affected.

RNF213 rare variants in an ethnically diverse population with Moyamoya disease.

BACKGROUND AND PURPOSE: Moyamoya disease (MMD) is a rare, genetically heterogeneous cerebrovascular disease resulting from occlusion of the distal internal carotid arteries. A variant in the Ring Finger 213 gene (RNF213), altering arginine at position 4810 (p.R4810K), is associated with MMD in Asian populations. However, there are a lack of data on the role of RNF213 in patients with MMD of additional ethnicities and diasporic Asian populations. We investigate the contribution of RNF213 alterations to MMD in an ethnically diverse population based in the United States. METHODS: We initially sequenced RNF213 exons 43, 44, and 45 (encoding the eponymous RING finger domain) and exon 60 (encoding p.R4810K) in 86 ethnically diverse patients with MMD. Comprehensive exome sequencing data from 24 additional patients with MMD was then analyzed to identify RNF213 variants globally. Segregation of variants with MMD and other vascular diseases was assessed in families. RESULTS: RNF213 p.R4810K was identified in 56% (9/16) of patients with MMD of Asian descent and not in 94 patients of non-Asian descent. 3.6% (4/110) of patients had variants in the exons encoding the RING finger domain. Seven additional variants were identified in 29% (7/24) of patients with MMD who underwent exome sequencing. Segregation analysis supported an association with MMD for 2 variants and a lack of association with disease for 1 variant. CONCLUSIONS: These results confirm that alterations in RNF213 predispose patients of diverse ethnicities to MMD, and that the p.R4810K variant predisposes individuals of Asian descent in the United States to MMD.

Identification of RNF213 as a susceptibility gene for moyamoya disease and its possible role in vascular development.

BACKGROUND: Moyamoya disease is an idiopathic vascular disorder of intracranial arteries. Its susceptibility locus has been mapped to 17q25.3 in Japanese families, but the susceptibility gene is unknown. METHODOLOGY/PRINCIPAL FINDINGS: Genome-wide linkage analysis in eight three-generation families with moyamoya disease revealed linkage to 17q25.3 (P<10(-4)). Fine mapping demonstrated a 1.5-Mb disease locus bounded by D17S1806 and rs2280147. We conducted exome analysis of the eight index cases in these families, with results filtered through Ng criteria. There was a variant of p.N321S in PCMTD1 and p.R4810K in RNF213 in the 1.5-Mb locus of the eight index cases. The p.N321S variant in PCMTD1 could not be confirmed by the Sanger method. Sequencing RNF213 in 42 index cases confirmed p.R4810K and revealed it to be the only unregistered variant. Genotyping 39 SNPs around RNF213 revealed a founder haplotype transmitted in 42 families. Sequencing the 260-kb region covering the founder haplotype in one index case did not show any coding variants except p.R4810K. A case-control study demonstrated strong association of p.R4810K with moyamoya disease in East Asian populations (251 cases and 707 controls) with an odds ratio of 111.8 (P = 10(-119)). Sequencing of RNF213 in East Asian cases revealed additional novel variants: p.D4863N, p.E4950D, p.A5021V, p.D5160E, and p.E5176G. Among Caucasian cases, variants p.N3962D, p.D4013N, p.R4062Q and p.P4608S were identified. RNF213 encodes a 591-kDa cytosolic protein that possesses two functional domains: a Walker motif and a RING finger domain. These exhibit ATPase and ubiquitin ligase activities. Although the mutant alleles (p.R4810K or p.D4013N in the RING domain) did not affect transcription levels or ubiquitination activity, knockdown of RNF213 in zebrafish caused irregular wall formation in trunk arteries and abnormal sprouting vessels. CONCLUSIONS/SIGNIFICANCE: We provide evidence suggesting, for the first time, the involvement of RNF213 in genetic susceptibility to moyamoya disease.

Moyamoya disease in Europeans.

BACKGROUND AND PURPOSE: We describe the clinical, diagnostic, and outcome features of a cohort of white patients with idiopathic moyamoya disease treated in a German institution. METHODS: Our cohort included 21 white patients with moyamoya disease. Clinical and diagnostic features were obtained by retrospective chart review; follow-up information and outcome were obtained prospectively. We used the Kaplan-Meier methods to estimate stroke risk by treatment status. RESULTS: The mean age at onset of symptoms was 31 years. The female predominance was 4.25:1. In our cohort, the initial symptom was a cerebral ischemic event in all patients. There was no patient with a hemorrhage at onset; only one patient experienced subarachnoidal hemorrhage in the further course of disease. The Kaplan-Meier risk for recurrent stroke was very high after the first ischemic event and smaller after angiographic diagnosis. The 5-year-Kaplan-Meier risk of recurrent stroke was 80.95% after the first ischemic event for all patients. Most subsequent ischemic events appeared in the first 2 years after symptom onset. Eleven patients (52.3%) underwent neurosurgical revascularizing procedures. After surgery, the Kaplan-Meier risk of perioperative or subsequent stroke was 27.27% within the first month and was stable thereafter. CONCLUSIONS: Clinical features and course of moyamoya disease of whites analyzed in this German study are comparable to American results. Moyamoya disease in whites differs clearly from Asian moyamoya disease in timing of onset of vasculopathy and lower rate of hemorrhages.

Moyamoya disease in patients of Finno-Ugric origin.

The terms moyamoya disease, moyamoya syndrome and moyamoya phenomenon can be found dispersed throughout the literature. The diagnostic criteria for moyamoya disease are: (1) stenosis or occlusion of the anterior cerebral, middle cerebral and internal carotid arteries, (2) an abnormal vascular network near these arteries and (3) bilateral findings. When only the two first conditions are present, the term moyamoya syndrome is used. The incidence of moyamoya disease is high in the Mongol race, although the moyamoya syndrome is more frequently reported among Caucasians. In the last two decades 41 cases of moyamoya were diagnosed in two Hungarian and two Scandinavian hospitals, respectively. Thirty-one patients were operated on 12 unilaterally and 19 bilaterally--either with extracranial/intracranial bypass (29 cases) or with encephalomyosynangiosis (2 cases). After a mean follow-up of seven years, 67.7% of the operated cases were symptom-free or neurologically improved. The majority of the patients had moyamoya disease and turned out to be of Finno-Ugric or Lapplandish ancestry. These people originally migrated from the East and belong to the Ural-Altaic family. Our findings suggest that while the moyamoya syndrome is found in different races, the moyamoya disease may be limited to people of Eastern (Mongol) origin. Revascularization surgery may be of benefit to patients with moyamoya.