C3 glomerulopathy is a group of related conditions that cause the kidneys to malfunction. The major features of C3 glomerulopathy include high levels of protein in the urine (proteinuria), blood in the urine (hematuria), reduced amounts of urine, low levels of protein in the blood, and swelling in many areas of the body. Affected individuals may have particularly low levels of a protein called complement component 3 (or C3) in the blood.

The kidney problems associated with C3 glomerulopathy tend to worsen over time. About half of affected individuals develop end-stage renal disease (ESRD) within 10 years after their diagnosis. ESRD is a life-threatening condition that prevents the kidneys from filtering fluids and waste products from the body effectively.

Researchers have identified two major forms of C3 glomerulopathy: dense deposit disease and C3 glomerulonephritis. Although the two disorders cause similar kidney problems, the features of dense deposit disease tend to appear earlier than those of C3 glomerulonephritis, usually in adolescence. However, the signs and symptoms of either disease may not begin until adulthood.

One of the two forms of C3 glomerulopathy, dense deposit disease, can also be associated with other conditions unrelated to kidney function. For example, people with dense deposit disease may have acquired partial lipodystrophy, a condition characterized by a lack of fatty (adipose) tissue under the skin in the upper part of the body. Additionally, some people with dense deposit disease develop a buildup of yellowish deposits called drusen in the light-sensitive tissue at the back of the eye (the retina). These deposits usually appear in childhood or adolescence and can cause vision problems later in life.

C3 glomerulopathy is very rare, affecting 1 to 2 per million people worldwide. It is equally common in men and women.

C3 glomerulopathy is associated with changes in many genes. Most of these genes provide instructions for making proteins that help regulate a part of the body's immune response known as the complement system. This system is a group of proteins that work together to destroy foreign invaders (such as bacteria and viruses), trigger inflammation, and remove debris from cells and tissues. The complement system must be carefully regulated so it targets only unwanted materials and does not damage the body's healthy cells.

A specific mutation in one of the complement system-related genes, CFHR5, has been found to cause C3 glomerulopathy in people from the Mediterranean island of Cyprus. Mutation in the C3 and CFH genes, as well as other complement system-related genes, have been found to cause the condition in other populations. The known mutations account for only a small percentage of all cases of C3 glomerulopathy. In most cases, the cause of the condition is unknown.

Several normal variants (polymorphisms) in complement system-related genes are associated with an increased likelihood of developing C3 glomerulopathy. In some cases, the increased risk is related to a group of specific variants in several genes, a combination known as a C3 glomerulopathy at-risk haplotype. While these polymorphisms increase the risk of C3 glomerulopathy, many people who inherit these genetic changes will never develop the condition.

The genetic changes related to C3 glomerulopathy "turn up," or increase the activation of, the complement system. The overactive system damages structures called glomeruli in the kidneys. These structures are clusters of tiny blood vessels that help filter waste products from the blood. Damage to glomeruli prevents the kidneys from filtering waste products normally and can lead to ESRD. Studies suggest that uncontrolled activation of the complement system also causes the other health problems that can occur with dense deposit disease, including acquired partial lipodystrophy and a buildup of drusen in the retina. Researchers are working to determine how these associated health problems are related to overactivity of the complement system.

Studies suggest that C3 glomerulopathy can also result from the presence of specialized proteins called autoantibodies. Autoantibodies cause the condition by altering the activity of proteins involved in regulating the complement system.

Genetic Testing Information

• Genetic Testing Registry: C3 Glomerulonephritis
• Genetic Testing Registry: CFHR5 deficiency
• Genetic Testing Registry: CFHR5-Related Dense Deposit Disease / Membranoproliferative Glomerulonephritis Type II
• Genetic Testing Registry: Factor H deficiency
• Genetic Testing Registry: Mesangiocapillary glomerulonephritis, type II

Genetic and Rare Diseases Information Center

• Dense deposit disease
• Glomerulonephritis

Patient Support and Advocacy Resources

• National Organization for Rare Disorders (NORD)

Clinical Trials

• ClinicalTrials.gov

Catalog of Genes and Diseases from OMIM

• COMPLEMENT FACTOR H DEFICIENCY; CFHD
• C3 GLOMERULOPATHY 3; C3G3

Scientific Articles on PubMed

• PubMed

• Abrera-Abeleda MA, Nishimura C, Frees K, Jones M, Maga T, Katz LM, Zhang Y, Smith RJ. Allelic variants of complement genes associated with dense deposit disease. J Am Soc Nephrol. 2011 Aug;22(8):1551-9. doi: 10.1681/ASN.2010080795. Epub 2011 Jul 22. Citation on PubMed or Free article on PubMed Central
• Barbour TD, Ruseva MM, Pickering MC. Update on C3 glomerulopathy. Nephrol Dial Transplant. 2016 May;31(5):717-25. doi: 10.1093/ndt/gfu317. Epub 2014 Oct 17. Citation on PubMed or Free article on PubMed Central
• Bu F, Borsa NG, Jones MB, Takanami E, Nishimura C, Hauer JJ, Azaiez H, Black-Ziegelbein EA, Meyer NC, Kolbe DL, Li Y, Frees K, Schnieders MJ, Thomas C, Nester C, Smith RJ. High-Throughput Genetic Testing for Thrombotic Microangiopathies and C3 Glomerulopathies. J Am Soc Nephrol. 2016 Apr;27(4):1245-53. doi: 10.1681/ASN.2015040385. Epub 2015 Aug 17. Citation on PubMed or Free article on PubMed Central
• Fakhouri F, Fremeaux-Bacchi V, Noel LH, Cook HT, Pickering MC. C3 glomerulopathy: a new classification. Nat Rev Nephrol. 2010 Aug;6(8):494-9. doi: 10.1038/nrneph.2010.85. Epub 2010 Jul 6. Citation on PubMed
• Martin B, Smith RJH. C3 Glomerulopathy. 2007 Jul 20 [updated 2018 Apr 5]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews(R) [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2024. Available from http://www.ncbi.nlm.nih.gov/books/NBK1425/ Citation on PubMed
• Medjeral-Thomas NR, O'Shaughnessy MM, O'Regan JA, Traynor C, Flanagan M, Wong L, Teoh CW, Awan A, Waldron M, Cairns T, O'Kelly P, Dorman AM, Pickering MC, Conlon PJ, Cook HT. C3 glomerulopathy: clinicopathologic features and predictors of outcome. Clin J Am Soc Nephrol. 2014 Jan;9(1):46-53. doi: 10.2215/CJN.04700513. Epub 2013 Oct 31. Citation on PubMed or Free article on PubMed Central
• Pickering MC, D'Agati VD, Nester CM, Smith RJ, Haas M, Appel GB, Alpers CE, Bajema IM, Bedrosian C, Braun M, Doyle M, Fakhouri F, Fervenza FC, Fogo AB, Fremeaux-Bacchi V, Gale DP, Goicoechea de Jorge E, Griffin G, Harris CL, Holers VM, Johnson S, Lavin PJ, Medjeral-Thomas N, Paul Morgan B, Nast CC, Noel LH, Peters DK, Rodriguez de Cordoba S, Servais A, Sethi S, Song WC, Tamburini P, Thurman JM, Zavros M, Cook HT. C3 glomerulopathy: consensus report. Kidney Int. 2013 Dec;84(6):1079-89. doi: 10.1038/ki.2013.377. Epub 2013 Oct 30. Citation on PubMed or Free article on PubMed Central
• Servais A, Noel LH, Roumenina LT, Le Quintrec M, Ngo S, Dragon-Durey MA, Macher MA, Zuber J, Karras A, Provot F, Moulin B, Grunfeld JP, Niaudet P, Lesavre P, Fremeaux-Bacchi V. Acquired and genetic complement abnormalities play a critical role in dense deposit disease and other C3 glomerulopathies. Kidney Int. 2012 Aug;82(4):454-64. doi: 10.1038/ki.2012.63. Epub 2012 Mar 28. Citation on PubMed
• Xiao X, Pickering MC, Smith RJ. C3 glomerulopathy: the genetic and clinical findings in dense deposit disease and C3 glomerulonephritis. Semin Thromb Hemost. 2014 Jun;40(4):465-71. doi: 10.1055/s-0034-1376334. Epub 2014 May 5. Citation on PubMed
• Zipfel PF, Skerka C, Chen Q, Wiech T, Goodship T, Johnson S, Fremeaux-Bacchi V, Nester C, de Cordoba SR, Noris M, Pickering M, Smith R. The role of complement in C3 glomerulopathy. Mol Immunol. 2015 Sep;67(1):21-30. doi: 10.1016/j.molimm.2015.03.012. Epub 2015 Apr 28. Citation on PubMed