von Willebrand factor variants in C3 glomerulopathy: A Chinese cohort study

C3 glomerulopathy (C3G) is a rare renal disease characterized by predominant glomerular C3 staining. Complement alternative pathway dysregulation due to inherited complement defects is associated with C3G. To identify novel C3G-related genes, we screened 86 genes in the complement, coagulation and endothelial systems in 35 C3G patients by targeted genomic enrichment and massively parallel sequencing. Surprisingly, the most frequently mutated gene was VWF. Patients with VWF variants had significantly higher proteinuria levels, higher crescent formation and lower factor H (FH) levels. We further selected two VWF variants to transiently express the von Willebrand factor (vWF) protein, we found that vWF expression from the c.1519A > G variant was significantly reduced. In vitro results further indicated that vWF could regulate complement activation, as it could bind to FH and C3b, act as a cofactor for factor I-mediated cleavage of C3b. Thus, we speculated that vWF might be involved in the pathogenesis of C3G.