Alternative titles; symbols
ORPHA: 329918, 329931, 54370;
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
Gene/Locus |
Gene/Locus MIM number |
|---|---|---|---|---|---|---|
| 1q31.3 | Nephropathy due to CFHR5 deficiency | 614809 | Autosomal dominant | 3 | CFHR5 | 608593 |
A number sign (#) is used with this entry because of evidence that C3 glomerulopathy-3 (C3G3) is caused by heterozygous mutation in the CFHR5 gene (608593) on chromosome 1q32.
C3 glomerulopathy-3 (C3G3) is an autosomal dominant kidney disease characterized by the onset of microscopic or macroscopic hematuria in the first 3 decades of life, followed by variable progression of renal disease. After age 30, about half of patients continue to have episodic hematuria while maintaining normal renal function, whereas the other half develop proteinuria and progressive renal failure or end-stage renal disease. In some cases, renal dysfunction may be triggered or exacerbated by an infectious disease, often an upper respiratory infection or pharyngitis. Some patients may also develop hypertension. Renal biopsy shows glomerular C3 deposition and mesangial proliferation with glomerulonephritis. Membranoproliferative glomerulonephritis (MPGN) may also be observed on renal biopsy. Males tend to have a more severe phenotype than females and are more likely to develop end-stage renal disease, often necessitating dialysis or renal transplant (summary by Athanasiou et al., 2011).
For a general description and discussion of genetic heterogeneity of C3G, see C3G1 (609814).
Gale et al. (2010) reported 2 unrelated families with an autosomal dominant form of glomerulonephritis resulting in renal failure. Both families had ancestors from the Troodos mountains of Cyprus. Additional patients of Cypriot origin with a similar disorder were subsequently identified. In all, there were 26 patients from 11 families. All had microscopic hematuria, and many developed macroscopic hematuria following upper respiratory tract infections. Renal biopsies showed glomerulonephritis with C3 (120700) deposits in the subendothelium and mesangium. There was also mesangial matrix expansion, increased glomerular cellularity, and segmental capillary wall thickening. The initial pathologic diagnosis in these patients was membranoproliferative glomerulonephritis type I, which was later refined to C3 glomerulonephritis. The risk of progression appeared to be greater in men than in women with the disease. None of the patients had evidence of retinal disease. In a comment on the report of Gale et al. (2010), Karumanchi and Thadhani (2010) noted the clinical similarity of this disorder, which they termed 'CFHR5 nephropathy,' to IgA nephropathy (161950).
Athanasiou et al. (2011) reported 91 patients from 16 families of Cypriot origin with C3G3. The cohort included the 26 patients reported by Gale et al. (2010). All affected individuals carried the exon 2-3 founder duplication mutation in the CFHR5 gene (608593.0001) in the heterozygous state. Clinical details were provided for 4 of the families, and general clinical information was provided for the remaining patients. There was wide phenotypic heterogeneity: about 10% of mutation carriers were asymptomatic, about half (56%) had episodes of macroscopic hematuria, and 31% had hematuria, hypertension, and proteinuria that developed into chronic renal failure and end-stage renal disease between 30 and 72 years of age. A few patients (3%) had hematuria and proteinuria but did not progress to end-stage renal disease. In some cases, the hematuria and renal disease were exacerbated following an upper respiratory infection. Renal biopsy, when performed, showed mesangial electron-dense deposits as well as thickening of the glomerular basement membrane due to intramembranous or subendothelial electron-dense deposits. C3 immunoreactivity was observed in the biopsies; serum C3 levels were normal. There was a striking gender difference, with males being more affected than females. Proteinuria with chronic renal failure was found in 35% of males compared to 0% of females between 31 and 50 years. This incidence rose to 80% in males over age 50, compared to about 20% of females over 50. Ten of 18 patients with end-stage renal disease underwent renal transplant with good results.
Besbas et al. (2014) reported a 16-year-old girl of Turkish descent with C3G3. She presented with periorbital edema, proteinuria, and low serum C3; she did not have hematuria. Renal biopsy showed membranoproliferative glomerulonephritis with C3 deposition, subendothelial deposits, and capillary basement membrane thickening. She did not have mutations in the CFH or CFI genes, but genetic analysis identified a heterozygous C269R variant in the CFHR5 gene that was predicted to be damaging. Functional studies of the variant were not performed. The report expanded the phenotype associated with CFHR5 variants.
Clinical Variability
Vernon et al. (2012) reported a girl who developed chronic glomerulonephritis with C3 deposits following a streptococcal infection. The patient presented at age 7 years with dark-colored proteinuria after a 10-day history of fever and sore throat. After treatment for the infection, she had persistent hematuria and proteinuria. Nine months later, kidney biopsy showed mesangial hypercellularity, segmental endocapillary hypercellularity, and segmental capillary wall double contours. There was mesangial and capillary deposition of C3, C9 (120940), and CFHR5. Electron microscopy showed thickening of the glomerular basement membranes, intramembranous electron-dense deposits, and subendothelial and subepithelial deposits. Twenty months after presentation, a second kidney biopsy showed persistent membranoproliferative glomerulonephritis with tubulointerstitial scarring. Serum CFHR5 was decreased to 37.3% of control values. Treatment with an angiotensin receptor (see 106165) blocker resulted in improved kidney function.
The transmission pattern of C3G3 in the Cypriot families reported by Gale et al. (2010) was consistent with autosomal dominant inheritance with incomplete penetrance.
By linkage analysis followed by candidate gene analysis in 2 Cypriot families with C3G3, Gale et al. (2010) identified a heterozygous duplication of exons 2 and 3 of the CFHR5 gene (608593.0001). The internal duplication was not seen in a set of 102 controls, but was found in 1 of 1,015 Cypriot controls. Screening of this gene in additional patients of Cypriot origin identified several more with the same duplication. In total, 26 patients from 11 ostensibly unrelated families with renal disease carried the mutation. Haplotype analysis performed in 5 families indicated a founder effect. In vitro functional expression studies showed that the mutant protein bound less well to surface-bound complement compared to wildtype. However, the mutant protein circulated and showed enhanced cofactor activity with complement factor I (CFI; 217030) compared to wildtype CFHR5. Although the precise pathomechanism, was unclear, the findings of abnormal complement deposition in patient renal biopsies indicated a defect in the regulation of C3.
Athanasiou et al. (2011) identified a heterozygous founder exon 2-3 duplication in the CFHR5 gene in several additional families of Cypriot origin with C3G3. Functional studies of the variant and studies of patient cells were not performed.
Kadkhodayi-Kholghi et al. (2020) noted that the exon 2-3 duplication in the CFHR5 gene results in the production of an elongated FHR5 protein with 2 extra N-terminal SCR-1/2 domains in tandem. Using detailed structural analysis, the authors determined that FHR5 forms dimers and is a complement deregulator that competitively inhibits factor H, an important regulator of C3b activation at host cell surfaces. They provided evidence that the duplication mutation alters the CFHR5 dimer structure and that the mutant protein competes with factor H binding, thus antagonizing the regulatory function of factor H. This results in amplification of complement activation at host cell surfaces when C3 deposition reaches a critical density. The findings were consistent with a gain-of-function effect rather than a deficiency. See also review by Wong and Kavanagh (2018).
In a girl with C3G3 and persistent renal disease following a streptococcal infection, Vernon et al. (2012) identified a heterozygous truncating variant in the CFHR5 gene (c.485dupA; 608593.0002). The variant was also present in her unaffected mother and sister, suggesting that presence of this variant is not sufficient to cause disease, but likely acts as a susceptibility factor for the development of glomerulonephritis.
Athanasiou, Y., Voskarides, K., Gale, D. P., Damianou, L., Patsias, C., Zavros, M., Maxwell, P. H., Cook, H. T., Demosthenous, P., Hadjisavvas, A., Kyriacou, K., Zouvani, I., Pierides, A., Deltas, C. Familial C3 glomerulopathy associated with CFHR5 mutations: clinical characteristics of 91 patients in 16 pedigrees. Clin. J. Am. Soc. Nephrol. 6: 1436-1446, 2011. [PubMed: 21566112] [Full Text: https://doi.org/10.2215/CJN.09541010]
Besbas, N., Gulhan, B., Gucer, S., Korkmaz, E., Ozaltin, F. A novel CFHR5 mutation associated with C3 glomerulonephritis in a Turkish girl. J. Nephrol. 27: 457-460, 2014. [PubMed: 24536001] [Full Text: https://doi.org/10.1007/s40620-013-0008-1]
Gale, D. P., Goicoechea de Jorge, E., Cook, H. T., Martinez-Barricarte, R., Hadjisavvas, A., McLean, A. G., Pusey, C. D., Pierides, A., Kyriacou, K., Athanasiou, Y., Voskarides, K., Deltas, C., Palmer, A., Fremeaux-Bacchi, V., Rodriguez de Cordoba, S., Maxwell, P. H., Pickering, M. C. Identification of a mutation in complement factor H-related protein 5 in patients of Cypriot origin with glomerulonephritis. Lancet 376: 794-801, 2010. [PubMed: 20800271] [Full Text: https://doi.org/10.1016/S0140-6736(10)60670-8]
Kadkhodayi-Kholghi, N., Bhatt, J. S., Gor, J., McDermott, L. C., Gale, D. P., Perkins, S. J. The solution structure of the complement deregulator FHR5 reveals a compact dimer and provides new insights into CFHR5 nephropathy. J. Biol. Chem. 295: 16342-16358, 2020. [PubMed: 32928961] [Full Text: https://doi.org/10.1074/jbc.RA120.015132]
Karumanchi, S. A., Thadhani, R. A complement to kidney disease: CFHR5 nephropathy. (Comment) Lancet 376: 748-750, 2010. [PubMed: 20800272] [Full Text: https://doi.org/10.1016/S0140-6736(10)60967-1]
Vernon, K. A., Goicoechea de Jorge, E., Hall, A. E., Fremeaux-Bacchi, V., Aitman, T. J., Cook, H. T., Hangartner, R., Koziell, A., Pickering, M. C. Acute presentation and persistent glomerulonephritis following streptococcal infection in a patient with heterozygous complement factor H-related protein 5 deficiency. Am. J. Kidney Dis. 60: 121-125, 2012. [PubMed: 22503529] [Full Text: https://doi.org/10.1053/j.ajkd.2012.02.329]
Wong, E. K. S., Kavanagh, D. Diseases of complement dysregulation--an overview. Semin. Immunopath. 40: 49-64, 2018. [PubMed: 29327071] [Full Text: https://doi.org/10.1007/s00281-017-0663-8]