The COL4A3 gene provides instructions for making one component of type IV collagen, which is a flexible protein. Specifically, this gene makes the alpha3(IV) chain of type IV collagen. This chain combines with two other types of alpha (IV) chains (the alpha4 and alpha5 chains) to make a complete type IV collagen molecule. Type IV collagen molecules attach to each other to form complex protein networks. These networks make up a large portion of basement membranes, which are thin sheet-like structures that separate and support cells in many tissues. Type IV collagen alpha3-4-5 networks play an especially important role in the basement membranes of the kidney, inner ear, and eye.
Health Conditions Related to Genetic Changes
More than 40 mutations in the COL4A3 gene have been found to cause Alport syndrome. Most of these mutations change single protein building blocks (amino acids) in a region where the alpha3(IV) collagen chain combines with other type IV collagen chains. Other mutations in the COL4A3 gene severely decrease or prevent the production of alpha3(IV) chains. As a result, there is a serious deficiency of the type IV collagen alpha3-4-5 network in the basement membranes of the kidney, inner ear, and eye. In the kidney, other types of collagen accumulate in the basement membranes, eventually leading to scarring of the kidneys and kidney failure. Mutations in this gene can also lead to abnormal function in the inner ear, resulting in hearing loss.More About This Health Condition
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Mutations in the COL4A3 gene have been found to cause thin basement membrane nephropathy. This condition typically causes people to have blood in their urine (hematuria) but no other signs or symptoms of kidney disease. In the past, this condition was often called benign familial hematuria. Thin basement membrane nephropathy rarely progresses to kidney failure.
Goodpasture syndrome is a severe disease of the lungs and the kidneys caused by antibodies to the alpha3(IV) collagen chains. Antibodies are immune system proteins that normally attack foreign substances such as bacteria or viruses, but in Goodpasture syndrome, they target alpha3(IV) collagen chains. It remains unclear why some people make antibodies to their own collagen chains. The antibodies cause inflammation when they attach (bind) to the basement membranes of blood vessels in the air sacs (alveoli) of the lungs and filtering units (glomeruli) of the kidneys. As a result, people with Goodpasture syndrome can develop kidney failure and bleeding in the lungs, which causes them to cough up blood. In some people, antibodies attack only the kidneys. These people are said to have anti-glomerular basement membrane nephritis.
Other Names for This Gene
- collagen IV, alpha-3 polypeptide
- collagen type IV alpha 3
- collagen, type IV, alpha 3 (Goodpasture antigen)
- Goodpasture antigen
Additional Information & Resources
Tests Listed in the Genetic Testing Registry
Scientific Articles on PubMed
- Frascà GM, Onetti-Muda A, Mari F, Longo I, Scala E, Pescucci C, Roccatello D, Alpa M, Coppo R, Li Volti G, Feriozzi S, Bergesio F, Schena FP, Renieri A; Italian Renal Immunopathology Group. Thin glomerular basement membrane disease: clinical significance of a morphological diagnosis--a collaborative study of the Italian Renal Immunopathology Group. Nephrol Dial Transplant. 2005 Mar;20(3):545-51. Epub 2004 Dec 23. Citation on PubMed
- Gregory MC. The clinical features of thin basement membrane nephropathy. Semin Nephrol. 2005 May;25(3):140-5. Review. Citation on PubMed
- Kashtan CE. Alport Syndrome. 2001 Aug 28 [updated 2019 Feb 21]. In: Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Mirzaa G, Amemiya A, editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2021. Available from http://www.ncbi.nlm.nih.gov/books/NBK1207/ Citation on PubMed
- Kashtan CE. Alport syndrome. An inherited disorder of renal, ocular, and cochlear basement membranes. Medicine (Baltimore). 1999 Sep;78(5):338-60. Review. Citation on PubMed
- Pescucci C, Mari F, Longo I, Vogiatzi P, Caselli R, Scala E, Abaterusso C, Gusmano R, Seri M, Miglietti N, Bresin E, Renieri A. Autosomal-dominant Alport syndrome: natural history of a disease due to COL4A3 or COL4A4 gene. Kidney Int. 2004 May;65(5):1598-603. Citation on PubMed
- Rana K, Wang YY, Buzza M, Tonna S, Zhang KW, Lin T, Sin L, Padavarat S, Savige J. The genetics of thin basement membrane nephropathy. Semin Nephrol. 2005 May;25(3):163-70. Review. Citation on PubMed
- Slajpah M, Gorinsek B, Berginc G, Vizjak A, Ferluga D, Hvala A, Meglic A, Jaksa I, Furlan P, Gregoric A, Kaplan-Pavlovcic S, Ravnik-Glavac M, Glavac D. Sixteen novel mutations identified in COL4A3, COL4A4, and COL4A5 genes in Slovenian families with Alport syndrome and benign familial hematuria. Kidney Int. 2007 Jun;71(12):1287-95. Epub 2007 Mar 28. Citation on PubMed
- Tazón Vega B, Badenas C, Ars E, Lens X, Milà M, Darnell A, Torra R. Autosomal recessive Alport's syndrome and benign familial hematuria are collagen type IV diseases. Am J Kidney Dis. 2003 Nov;42(5):952-9. Citation on PubMed
- Wang YY, Rana K, Tonna S, Lin T, Sin L, Savige J. COL4A3 mutations and their clinical consequences in thin basement membrane nephropathy (TBMN). Kidney Int. 2004 Mar;65(3):786-90. Citation on PubMed