Systematic Validation of RNF213 Coding Variants in Japanese Patients With Moyamoya Disease

Abstract

BackgroundA founder variant of RNF213, p.R4810K (c.14429G>A, rs112735431), was recently identified as a major genetic risk factor for moyamoya disease (MMD) in Japan. Although the association of p.R4810K was reported to be highly significant and reproducible, the disease susceptibility of other RNF213 variants remains largely unknown. In the present study, we systematically evaluated the coding variants detected in Japanese patients and controls for associations with MMD.Methods and ResultsTo detect variants of RNF213, all coding exons were sequenced in 27 Japanese MMD patients without p.R4810K. We also validated all previously reported variants in our case–control samples and tested for associations in combination with previous Japanese study cohorts, including the 1000 Genomes Project data set, as population-based controls. Forty-six missense variants other than p.R4810K were identified among 370 combined patients and 279 combined controls in Japan. Sixteen of 46 variants were polymorphisms with minor allele frequency >1%, and, after conditioning on the p.R4810K genotype, were not associated with MMD. We conducted a variable threshold test using Combined Annotation-Dependent Depletion on the remaining 30 rare variants (minor allele frequency <1%), and the results showed that the frequency of potentially functional variants was significantly higher in patients than in controls (permutation, minimum P=0.045).ConclusionsNot only p.4810K but also other functional missense variants of RNF213 conferred susceptibility to MMD. Our analysis also revealed that ≈20% of Japanese MMD patients did not harbor susceptibility variants of RNF213, indicating the presence of other susceptibility genes for MMD.

Genotype-Phenotype Correlation in Long-Term Cohort of Japanese Patients with Moyamoya Disease

“…Interestingly, the patients with the homozygous p. R4810K variant were stable without increased likelihood of recurrent stroke after revascularization. According to our data, it is difficult to predict prognosis after revascularization using the p.R4810K founder variant as a prognostic biomarker, though the homozygous founder variant may influence some aspects of the disease, such as the age of onset, as suggested by prior reports [6,7].…”

“…Several studies confirmed that homozygosity of this RNF213 founder variant influenced the severity of the clinical disease phenotype [6][7][8]. A previous Japanese study showed that its homozygosity was significantly associated with early-onset MMD and cerebral infarction at diagnosis [7].…”

“…We identified 3 RNF213 p.R4810K founder variant genotypes (GG/GA/AA) by direct sequencing, setting NM_001256071.1 as the reference transcriptional sequence of RNF213 in the GRCh37 (hg19) coordinate. The genetic data have been partially included in a previously published report regarding rare variant analysis [6].…”

“…This may be because this variant is not located within the functional domains (2 AAAATPase domains and a RING domain) in RNF213, of which the function or the role is not completely analyzed yet. Moreover, rare variants other than the p.R4810K variant were also found in Asian and European patients with MMD [4,6,18,19]. Some of those variants appear to be more pathogenic than the p.R4810K founder variant in in-silico prediction tools, such as PolyPhen or C-score of Combined Annotation Dependent Depletion [20][21][22].…”

Cerebrovascular disorders associated with genetic lesions

“…Of interest, homozygosity for the R4810K variant leads to MMD with extracranial systemic vasculopathy [165]. Given that around 80 % of Japanese MMD patients harbor susceptibility variants of RNF213 , 17q25.3 is considered a major disease locus [159, 161], however, the lack of a cerebrovascular phenotype in Rnf213 knockout mice and high prevalence of RNF213 variants in healthy control populations suggest multifactorial etiology [166]. On the other hand, autosomal-recessive MMD with achalasia has been associated with mutations in GUCY1A3 on chromosome 4q32.1 [167], encoding a subunit of the main receptor for nitric oxide (NO) [168].…”