Delineating the Genetic Basis of RNF213-related vasculopathies: The association of PKHD1 variants with bilateral cerebral vasculopathy

Moyamoya disease (MMD) is an idiopathic cerebrovascular disorder characterized by progressive stenosis of the internal carotid artery termini and the formation of an abnormal network of fragile perforators. Although the RNF213 gene has been implicated as a susceptibility factor for MMD, the precise genetic basis of the disease remains elusive. This study aimed to investigate other genetic factors contributing to differences in disease manifestation and vascular phenotypes. We conducted whole-exome sequencing of patients with RNF213-related vasculopathy and healthy controls. In total, 122 patients (comprising 69 with bilateral MMD, 13 with unilateral MMD, and 40 with intracranial artery stenosis [ICAS]) and 458 controls were enrolled. Following appropriate quality control measures, case-control analysis and in-case analysis (bilateral MMD vs. unilateral MMD and ICAS) were conducted using single-variant association testing and gene-based aggregation testing. Although no significant locus or gene was found in the case-control analysis, the PKHD1 gene emerged as a top candidate associated with bilateral MMD in the in-case analysis. Two rare damaging variants, p.Ile2364Asn and p.Ser3210Cys, were significantly more prevalent in the bilateral MMD group and were further validated in an independent cohort of 216 individuals. Publicly available single-cell transcriptome data of mouse cerebrovascular and perivascular cells revealed that Pkhd1 expression was significantly higher in specific endothelial-cell clusters. Despite some limitations, our study provides new insights into the potential role of the PKHD1 gene in bilateral MMD, highlighting the need for further investigation of endothelial gene expression in patients with RNF213 and PKHD1 mutations.