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Prevalence of RNF213 p.R4810K Variant in Early-Onset Stroke With Intracranial Arterial Stenosis

Originally publishedhttps://doi.org/10.1161/STROKEAHA.118.024712Stroke. 2019;50:1561–1563

Abstract

Background and Purpose—

The ring finger protein 213 gene (RNF213) is a susceptibility gene for moyamoya disease and large-artery ischemic stroke in East Asia. We examined the prevalence and correlates of the RNF213 p.R4810K variant in patients with early-onset ischemic stroke in a Japanese single-center cohort.

Methods—

We analyzed 70 early-onset stroke patients with intracranial arterial stenosis who developed a noncardioembolic stroke or transient ischemic attack from 20 to 60 years of age. Patients with moyamoya disease were excluded.

Results—

The RNF213 p.R4810K variant was found in 17 patients (24%), and more often in women than men (38% versus 16%, odds ratio 3.3; 95% CI, 1.1–10.2, P=0.04). The variant was identified in 35% of patients with stenosis in the M1 segment of the middle cerebral artery or the A1 segment of the anterior cerebral artery (odds ratio, 25.0; 95% CI, 1.4–438; P<0.01) but in only one patient (9%) with intracranial posterior circulation stenosis. Conventional atherosclerotic risk factors did not differ between variant carriers and noncarriers.

Conclusions—

The RNF213 p.R4810K variant is common in early-onset ischemic stroke with anterior circulation stenosis in Japan. Further investigation of the RNF213 gene will provide new insights into pathogenetic mechanisms of early-onset stroke.

The ring finger protein 213 gene (RNF213) has been identified as a susceptibility gene for moyamoya disease in East Asia.1,2 This gene encodes a large protein containing 2 ATPases associated with diverse cellular activities+ ATPases and an E3 ligase domain, which plays an important role in regulating vascular endothelial function and angiogenesis.2,3 In Japan, about 90% of patients with moyamoya disease have the RNF213 p.R4810K (rs112735431) variant,1,2 whereas 1% to 2% of healthy subjects have this variant.1,4,5 Recently, a large case-control study, which included over 46 000 Japanese participants, demonstrated this variant is also a risk factor for ischemic stroke.6 The mean age of stroke onset is lower in RNF213 variant carriers, and the variant is strongly associated with a large-artery atherosclerosis subtype, which occurs due to intracranial arterial stenosis.6 Based on these results, we hypothesized this variant is a key factor of early-onset ischemic stroke with intracranial arterial stenosis, a common stroke subtype in East Asia.7 We, therefore, examined the prevalence and clinical correlates of the RNF213 p.R4810K variant in patients with early-onset ischemic stroke.

Methods

This single-center cross-sectional study was performed at the National Cerebral and Cardiovascular Center, Osaka, Japan. The study was conducted in accordance with Declaration of Helsinki standards and approved by the local ethics committee of National Cerebral and Cardiovascular Center (NCVC) and the ethics committee of Kyoto University. All participants signed a comprehensive consent form for the NCVC biobank. Patients who satisfied the following criteria were included: (1) participants in NCVC biobank from January 2011 to January 2017, (2) patients who developed a first noncardioembolic stroke or transient ischemic attack from 20 to 60 years of age, (3) patients with intracranial arterial stenosis defined as a diameter reduction of >50% or occlusion in an intracranial internal carotid artery, M1-M2 segment of a middle cerebral artery, A1-A2 segment of an anterior cerebral artery, P1-P2 segment of a posterior cerebral artery, or a basilar artery. The diagnosis of cerebrovascular lesion was made based on magnetic resonance angiography, computed tomography angiography, or digital subtraction angiography.

Patients with moyamoya disease were excluded based on recent diagnostic criteria.8 A flow diagram of patient selection is detailed in Figure I in the online-only Data Supplement. We investigated the prevalence of the RNF213 p.R4810K variant and its association with conventional atherosclerotic risk factors (hypertension, dyslipidemia, diabetes mellitus, and smoking incidence), family history of moyamoya disease within second degree of kinship, and radiological findings.

Peripheral blood samples were obtained from all patients. Genotyping was performed using TaqMan SNP Assays (Applied Biosystems, Foster City, CA), as described previously.2

Significance was determined at the level of 0.05 by Student t tests for continuous variables and Fisher exact tests for categorical variables. All analyses were performed with JMP Pro version 14.0.0 (SAS Institute, Inc, Cary, NC).

Results

The mean age of first stroke/ transient ischemic attack onset was 46±9.5 years old (range, 22–59). The Table shows the characteristics of patients with and without the RNF213 p.R4810K variant. Among the 70 participants, 17 (24%) had the heterozygote GA genotype for p.R4810K, and none had the homozygote AA genotype. The RNF213 p.R4810K variant was found more often in women than men (38% [10 of 26] versus 16% [7 of 44], odds ratio, 3.3; 95% CI, 1.1–10.2; P=0.04). Family history of moyamoya disease was more frequent in variant carriers (18% versus 0%; odds ratio, 25.8; 95% CI, 1.3–529). There was no difference in the frequency of conventional atherosclerotic risk factors between variant carriers and noncarriers. All 17 variant carriers had stenosis in the anterior circulation, whereas only one carrier had additional stenosis in the posterior circulation. In patients with M1 or A1 stenosis, 35% had the variant (17 of 48, odds ratio 25.0, 95% CI 1.4–438, P<0.01). In contrast, there was no variant carrier in 13 patients with internal carotid artery stenosis localized in the C2 to C5 segments, or in 6 patients with middle cerebral artery stenosis localized in the M2 segment. A summary of all variant carriers is shown in Table I in the online-only Data Supplement. Two representative cases are shown in Figure II in the online-only Data Supplement.

Table. Comparisons Between Stroke Patients With and Without RNF213 p.R4810K Variant

p.R4810K Variant Carriers; N =17p.R4810K Variant Noncarriers; N =53P ValueOdds Ratio95% CI
Age of stroke onset, y (mean±SD)44.4±2.346.6±1.30.21
Women10 (59%)16 (30%)0.043.31.1–10.2
Hypertension9 (53%)33 (62%)0.570.70.2–2.1
Dyslipidemia7 (41%)34 (64%)0.160.40.1–1.2
Diabetes mellitus2 (12%)13 (25%)0.330.40.08–2.0
Smoking incidence8 (47%)26 (49%)1.000.90.3–2.7
Family history of moyamoya disease3 (18%)0 (0%)0.0125.81.3–529
Anterior circulation stenosis17 (100%)46 (87%)0.185.70.3–104
MCA or ACA stenosis17 (100%)37 (70%)0.0115.40.9–272
M1 or A1 stenosis17 (100%)31 (58%)<0.0125.01.4–438
Posterior circulation stenosis1 (6%)10 (19%)0.270.30.03–2.3

Categorical variables are expressed as number (%). Number in parentheses indicates the percentage of cases in each group. A1 indicates A1 segment of the ACA; ACA, anterior cerebral artery; M1, M1 segment of the MCA; and MCA, middle cerebral artery.

Discussion

The main finding of this study is that the carrier frequency of the RNF213 p.R4810K variant is considerably high in early-onset ischemic stroke patients with intracranial arterial stenosis, especially those with M1 or A1 stenosis.

A unique characteristic of this study is a broad coverage of various types of intracranial arterial stenosis, such as stenoses in the posterior circulation, C2 to C5 portion of the internal carotid artery, or middle cerebral artery–M2, to determine whether the above association is region-specific. As a result, the association of the RNF213 p.R4810K variant with intracranial anterior circulation stenosis was found to be highly specific: the variant was associated with stenosis of M1 or A1, common sites of moyamoya disease–related vasculopathy, but rarely with posterior circulation stenosis or distal intracranial arterial stenosis. Previous reports have shown that the variant was also found in 20% to 25% in patients with distal internal carotid artery or proximal middle cerebral artery stenosis, who did not fulfill the diagnostic criteria for moyamoya disease.9,10 In addition, our results indicate apparent sex-difference in the prevalence of the RNF213 variant in consistency with our previous finding.6 These data imply the continuity between early-onset stroke with intracranial arterial stenosis and moyamoya disease within the same spectrum of RNF213-related vasculopathy.6

A potential limitation could have arisen due to the study being conducted at a tertiary referral hospital specialized for stroke and cardiovascular diseases. Selection biases may have thus led to an overestimation in the carrier frequency of the RNF213 variant. In addition, because of the nature of a cross-sectional study, it cannot be determined whether these nonmoyamoya patients with intracranial arterial stenosis will develop moyamoya disease in future. Further longitudinal studies are needed to confirm the association of this variant with early-onset stroke and moyamoya disease.

Conclusions

This study demonstrates the RNF213 p.R4810K variant is common in early-onset ischemic stroke with anterior circulation stenosis in Japan. Further investigation of the RNF213 gene will provide new insights into pathogenetic mechanisms of early-onset stroke.

Acknowledgments

We thank Dr Ahmad Khundakar for intellectual input and article editing. This research was performed using samples acquired from the National Center Biobank Network (NCBN)/ NCVC Biobank resource. For further details see http://www.ncbiobank.org/ and http://www.ncvc.go.jp/biobank/.

Footnotes

The online-only Data Supplement is available with this article at https://www.ahajournals.org/doi/suppl/10.1161/STROKEAHA.118.024712.

Correspondence to Shuhei Okazaki, MD, PhD, Department of Neurology, National Cerebral and Cardiovascular Center, 5-7-1 Fujishiro-dai, Suita, Osaka 565–8565, Japan. Email

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