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Homozygous C3 deficiency associated with IgA nephropathy
1Department of Internal Medicine, School of Medicine, Tokai University, Isehara, Japan.
Nephron
|January 1, 1991
Summary
A patient with zero C3 complement developed IgA nephropathy. This suggests an alternative complement pathway may drive kidney disease without C3.
Area of Science:
- Nephrology
- Immunology
- Complement System
Background:
- Homozygous C3 deficiency is a rare genetic condition.
- The complement system plays a crucial role in innate immunity.
- IgA nephropathy is the most common primary glomerulonephritis.
Observation:
- A 23-year-old male with homozygous C3 deficiency presented with asymptomatic proteinuria and hematuria.
- Renal biopsy revealed IgA nephropathy.
- Complement components C1q, C4, C2, C5, C7, C8, and C9 were detected in glomeruli, but C3 was absent.
Findings:
- Despite the complete absence of C3, deposition of early (C1q, C4, C2) and late (C5, C7, C8, C9) complement components was observed.
- The membrane attack complex (MAC) was present in the glomeruli.
- This indicates complement activation occurred via a C3-independent mechanism.
Implications:
- This case challenges the established understanding of complement activation in IgA nephropathy.
- It suggests the existence of alternative complement pathways that can mediate kidney damage.
- Further research is needed to elucidate these C3-independent mechanisms and their clinical relevance in kidney diseases.