Homozygous C3 deficiency associated with IgA nephropathy

A 23-year-old male patient with homozygous C3 deficiency who developed asymptomatic proteinuria and hematuria was reported. Renal biopsy disclosed typical IgA nephropathy with deposition of early- and late-complement components except for C3 deposition. C9 and membrane attack complex were detected in the glomeruli despite the absence of C3. It was suggested that there might be some unknown complement activation mechanism which does not require C3 component.