Related Experiment Videos
C4A deficiency and poor prognosis in patients with IgA nephropathy
R J Wyatt1, B A Julian, S Y Woodford
1Department of Pediatrics, University of Tennessee, Memphis.
Insights
Total deficiency of the C4A protein in IgA nephropathy patients was linked to chronic renal insufficiency. This suggests a role for complement system alterations in severe IgA nephropathy progression.
Area of Science:
- Nephrology
- Immunology
- Genetics
Background:
- IgA nephropathy (Berger's disease) is a significant cause of end-stage renal failure.
- It disproportionately affects individuals of Asian and European descent.
Purpose of the Study:
- To investigate the association between C4A protein deficiency and the clinical severity of IgA nephropathy.
- To explore the role of complement system alterations in the progression of kidney disease.
Main Methods:
- C4 phenotyping was performed on plasma samples from 123 adult patients diagnosed with IgA nephropathy.
- Patients' medical records were reviewed for clinical outcomes, including renal insufficiency (serum creatinine > 1.4 mg/dl).
Main Results:
- Six patients (4.9%) exhibited total C4A protein deficiency, and all had chronic renal insufficiency.
- In contrast, 47% of patients without C4A deficiency presented with chronic renal insufficiency (p = 0.001).
- C4A gene defects included homozygous and heterozygous deletions.
Conclusions:
- Functional alterations in the complement system, specifically C4A deficiency, may contribute to the development of clinically severe IgA nephropathy.
- C4A deficiency is associated with a higher likelihood of chronic renal insufficiency in patients with IgA nephropathy.
Abstract:
IgA nephropathy (Berger's disease) is an important cause of end-stage renal failure in persons of Asian and European descent. We performed C4 phenotyping on plasma from 123 patients with IgA nephropathy who resided in several different parts of the United States. All of these patients underwent diagnostic renal biopsy in adulthood. Six patients had a total deficiency for the C4A protein and all six had chronic renal insufficiency (serum creatinine concentration higher than 1.4 mg/dl at last follow-up). In contrast, 47% of the patients without C4A deficiency had chronic renal insufficiency (p = 0.001). The C4 gene defect was due to deletion of both C4A genes in only two individuals, whereas three patients were heterozygous for the C4A gene deletion. We speculate that the functional alteration of the complement system related to C4A deficiency might lead to expression of clinically severe disease in an individual with a genetic susceptibility to IgA nephropathy.