The Association of Heterozygous p.R4810K of RNF213 and Long-Term Unfavorable Outcomes after Encephaloduroarteriosynangiosis in Chinese Pediatric Patients with Moyamoya Disease

Background. Previous studies have established that heterozygous mutation for the p.R4810K variant can influence the severity of the clinical phenotype in patients with moyamoya disease (MMD) at disease onset. However, the relationship between the p.R4810K variant and the clinical phenotype of long-term unfavorable outcomes in Chinese pediatric patients remains unclear. Objectives. The primary aim of this study was to examine the association of heterozygous p.R4810K of RNF213 and long-term unfavorable outcomes after encephaloduroarteriosynangiosis (EDAS) in Chinese pediatric patients with MMD. Method. In this retrospective cohort study, we included 259 pediatric patients with MMD who possessed the known p.R4810K genotype. These individuals underwent EDAS along with genotyping analysis for p.R4810K via a TaqMan probe and the QuantStudio 6 Flex Real-Time PCR System. Subsequently, we evaluated their long-term outcomes. The variables we assessed were age at diagnosis, gender, p.R4810K genotypes, initial modified Rankin scale (mRS), clinical manifestations (such as hemorrhage and ischemia), posterior cerebral artery (PCA) involvement combined with angiographic stage, and their history of risk factors like hyperlipidemia and hyperhomocysteinemia. Furthermore, we scrutinized long-term unfavorable outcomes using both univariate analyses and multivariate logistic regression to identify independent predictive factors. Results. This study enrolled 259 Chinese pediatric patients with MMD, which included both newly and previously diagnosed cases, who underwent EDAS. The cohort comprised 130 male participants (50.19%) and 129 female participants (49.81%), with a median onset age of 8 years (median, IQR: 6-12 years). Among these patients, homozygous mutations were exceptionally rare, identified in only 4 individuals (1.54%), while the prevalence of heterozygous mutations was relatively higher, observed in 85 children (32.82%). The multivariate logistic regression showed that several factors were significantly associated with long-term unfavorable outcomes: older age at diagnosis (OR, 0.82 [95% CI, 0.7-0.96], P = 0.014), onset with hematoma (OR, 12.76 [95% CI, 1.52-106.89], P = 0.019), initial mRS (OR, 24.53 [95% CI, 6.51-92.41], P < 0.001), perioperative infarction (OR, 22.16 [95% CI, 1.45-337.96], P = 0.026), and infarction during follow-up (OR, 14.5 [95% CI, 2.04-103.12], P = 0.008). Furthermore, the cumulative incidence of initial infarction suggested that pediatric patients with homozygous or heterozygous mutations typically present at a younger age and exhibit a higher incidence of initial infarction compared to those carrying wild-type genotypes. Conclusions. The study suggests that the p.R4810K variant is associated with the onset age of MMD in Chinese pediatric patients, potentially impacting long-term outcomes. Surprisingly low recurrent stroke rates were observed across all genotypes, including homozygous individuals for the pathogenic variant, indicating that nongenetic factors may also play a role in the course and outcomes of MMD in this population.