C3 alleles in diseases associated with C3 activation
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This study investigated complement C3 genetic polymorphism in IgA nephropathy, membranoproliferative glomerulonephritis, and systemic lupus erythematosus. No significant differences in C3 gene frequencies were found between patients and healthy controls, refuting prior associations.
Area of Science:
- Immunogenetics
- Complement System Biology
- Nephrology
Background:
- The complement component 3 (C3) protein plays a crucial role in immune responses.
- Genetic variations in C3 have been implicated in various autoimmune and kidney diseases.
- Previous studies suggested an association between C3*F allele and IgA nephropathy.
Purpose of the Study:
- To investigate the association between C3 genetic polymorphism and the susceptibility to IgA nephropathy, membranoproliferative glomerulonephritis, and systemic lupus erythematosus.
- To validate or refute previously reported associations between C3 variants and these diseases.
Main Methods:
- Immunofixation electrophoresis was used to determine C3 phenotypes.
- C3 genetic polymorphism was analyzed in 100 healthy controls.
- Patient cohorts included 31 with IgA nephropathy, 33 with membranoproliferative glomerulonephritis, and 30 with systemic lupus erythematosus.
Main Results:
- Allele frequencies for C3*S (0.80) and C3*F (0.20) in controls matched published data.
- Phenotype frequencies (C3S: 0.65, C3SF: 0.29, C3F: 0.06) were consistent with previous reports.
- No statistically significant differences in C3 genetic polymorphism were observed between any of the patient groups and healthy controls.
Conclusions:
- The study did not confirm the previously reported association between C3*F and IgA nephropathy.
- No significant relationship was found between C3 genetic polymorphism and systemic lupus erythematosus or membranoproliferative glomerulonephritis.
- C3 genetic variations do not appear to be a major risk factor for these specific kidney and autoimmune diseases in the studied population.
Abstract:
C3 genetic polymorphism was examined by immunofixation electrophoresis in 100 healthy controls and in patients with three diseases in which this complement protein appears to be involved pathogenically (IgA nephropathy 31; membranoproliferative glomerulonephritis 33; systemic lupus erythematosus 30). C3*S (0.80) and C3*F (0.20) frequencies in controls were similar to those published in the literature, as were the frequencies of the C3 phenotypes C3S (0.65), C3SF (0.29), and C3F (0.06). No patient group had frequencies which differed significantly from controls. Thus, the previously reported association between C3*F and IgA nephropathy was not confirmed, and no relationships between C3 polymorphism and systemic lupus erythematosus or membranoproliferative glomerulonephritis were recognized.