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Afferent arteriolar C3 disease--a distinct pathological entity
C A Pollock1, L S Ibels, R P Eckstein
1Department of Renal Medicine, Royal North Shore Hospital, St Leonards NSW, Australia.
Insights
Afferent arteriolar C3 deposition is a distinct hereditary kidney disease, often presenting with hematuria. Renal function remains stable, indicating an excellent long-term prognosis for affected individuals.
Area of Science:
- Nephrology
- Genetics
- Pathology
Background:
- Afferent arteriolar C3 deposition is a rare renal biopsy finding.
- Its clinical significance and inheritance pattern were previously unclear.
Purpose of the Study:
- To characterize the clinical, histological, and genetic features of afferent arteriolar C3 deposition.
- To differentiate this entity from thin basement membrane disease.
Main Methods:
- Retrospective analysis of 959 renal biopsies over 10 years.
- Clinical evaluation, urine microscopy, and renal biopsy in patients and relatives.
- Histological examination including glomerular basement membrane thickness.
Main Results:
- Afferent arteriolar C3 deposition found in 118 patients, primarily presenting with hematuria.
- Evidence of autosomal dominant inheritance in affected families.
- No significant difference in renal function or clinical presentation compared to controls.
- No arteriolar C3 deposition in autopsy specimens without known renal disease.
Conclusions:
- Afferent arteriolar C3 deposition represents a distinct hereditary kidney disease.
- Clinically indistinguishable from thin basement membrane disease.
- Associated with a stable renal function and excellent long-term prognosis.
Abstract:
Afferent arteriolar C3 deposition was the sole histological abnormality in 79 and the major histological abnormality in an additional 39 of 959 renal biopsies performed over a 10-year period. Of these 79 patients, hematuria was the presenting symptom in 90%, with coincident loin pain in 49%. Urine microscopy of asymptomatic first-degree relatives revealed hematuria in 44% of children and siblings and 54% of parents, suggesting autosomal dominant inheritance. Arteriolar C3 deposition was confirmed by biopsy in four asymptomatic relatives with hematuria. Generalized thinning of glomerular basement membrane (less than 200 nm) was observed in five patients and focal thinning was observed in six patients with coincident afferent arteriolar C3 deposition. Seven other patients were identified as having generalized thinning of glomerular basement membrane in the absence of afferent arteriolar C3 deposition. Renal function was stable and similar in all groups studied over 37.9 +/- 23.7 months. No difference in clinical presentation or urinary abnormalities was evident between the groups. No arteriolar C3 deposition was evident in eight autopsy specimens with no known renal disease. It was concluded that afferent arteriolar C3 deposition is a marker of a distinct hereditary pathological entity, with differentiation from thin basement membrane disease not possible on clinical grounds. The medium- and long-term prognoses with respect to renal function are excellent.