Background: C3 glomerulopathy is a recently described entity classified as complementassociated glomerular disease.
Case Presentation: We report a case of a 48-year-old man referred to the nephrology
department for nephrotic syndrome with rapidly progressive kidney failure, acquired
partial lipodystrophy and drusen in Bruch’s membrane of the retina. Blood tests showed
low C3 and no evidence for autoimmune diseases, monoclonal gammopathy or infection.
The renal biopsy revealed a proliferative endocapillary and crescentic glomerulonephritis
with glomerular deposits exclusively of C3 and significant interstitial fibrosis. The electronic
microscopy was consistent with dense deposit disease. The complement analysis revealed a
pathogenic mutation of the complement factor B (CFB) gene not previously described in
Conclusions: The authors report a new mutation of CFB, in a dense deposit disease patient;
this finding brings a new insight to the pathogenic pathway of C3 glomerulopathy and
possibly to other complement dysregulation associated glomerular diseases. More clinical
trials are needed to clarify both the pathogenicity and the optimal treatment for these
Implication for health policy/practice/research/medical education:
The finding of a new mutation of complement factor B together with a haplotype for the complement factor H (CFH) known
to confer risk for atypical haemolytic uremic syndrome (AHUS), in a dense deposit disease patient, brings a new insight to the
pathogenic pathway of C3 glomerulopathy and possibly to other complement dysregulation associated glomerular diseases.
More clinical trials are needed to clarify both the pathogenicity and the optimal treatment for these entities.
Please cite this paper as: Coelho SS, Fernandes AR, Soares E, Valério P, Matos B, Romão H, et al. A new complement factor
B mutation associated with crescentic C3 glomerulopathy; a case report. J Nephropathol. 2019;8(3):e30. doi: 10.15171/