Reviewed April 2010
What is the official name of the AQP2 gene?
The official name of this gene is “aquaporin 2 (collecting duct).”
AQP2 is the gene's official symbol. The AQP2 gene is also known by other names, listed below.
What is the normal function of the AQP2 gene?
The AQP2 gene provides instructions for making a protein called aquaporin 2. This protein forms a channel that carries water molecules across cell membranes. It is found in the kidneys in structures called collecting ducts, which are a series of small tubes that reabsorb water from the kidneys into the bloodstream.
The aquaporin 2 water channel plays an essential role in maintaining the body's water balance. The placement of these channels is controlled by a hormone called vasopressin or antidiuretic hormone (ADH). When a person's fluid intake is low or when a lot of fluid is lost (for example, through sweating), the body produces more ADH. This hormone triggers chemical reactions that ultimately insert aquaporin 2 water channels into the membrane of collecting duct cells. These channels allow water to be reabsorbed into the bloodstream, which makes the urine more concentrated. When fluid intake is adequate, less ADH is produced. Without signals from ADH, aquaporin 2 water channels are removed from the membrane of collecting duct cells. At these times, less water is reabsorbed into the bloodstream and the urine is more dilute.
How are changes in the AQP2 gene related to health conditions?
- nephrogenic diabetes insipidus - caused by mutations in the AQP2 gene
At least 40 mutations in the AQP2 gene have been identified in people with nephrogenic diabetes insipidus.
Most of the known AQP2 gene mutations cause the aquaporin 2 protein to be misfolded into an incorrect 3-dimensional shape. The misfolded protein is trapped within the cell, where it is unable to reach the cell membrane to transport water molecules. A few mutations result in the production of functional aquaporin 2 water channels, but these channels are misrouted within the cell and do not reach the cell membrane.
If aquaporin 2 water channels are not inserted into the membrane of collecting duct cells, the kidneys are unable to respond to signals from ADH. As a result, collecting ducts do not reabsorb water as they should, and the body makes excessive amounts of urine. These problems with water balance are characteristic of nephrogenic diabetes insipidus.
Where is the AQP2 gene located?
Cytogenetic Location: 12q12-q13
Molecular Location on chromosome 12: base pairs 49,950,741 to 49,958,881
The AQP2 gene is located on the long (q) arm of chromosome 12 between positions 12 and 13.
More precisely, the AQP2 gene is located from base pair 49,950,741 to base pair 49,958,881 on chromosome 12.
See How do geneticists indicate the location of a gene? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genelocation) in the Handbook.
Where can I find additional information about AQP2?
You and your healthcare professional may find the following resources about AQP2 helpful.
Educational resources - Information pages
- Colorado State University: Antidiuretic Hormone (Vasopressin) (http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/adh.html)
- Molecular Cell Biology (2000): Water Channels Are Necessary for Bulk Flow of Water Across Cell Membranes (http://www.ncbi.nlm.nih.gov/books/NBK21739/)
- Gene Reviews - Clinical summary (http://www.ncbi.nlm.nih.gov/books/NBK1177)
Genetic Testing Registry - Repository of genetic test information
- GTR: Genetic tests for AQP2 (http://www.ncbi.nlm.nih.gov/gtr/tests/?term=359%5Bgeneid%5D)
You may also be interested in these resources, which are designed for genetics professionals and researchers.
- PubMed - Recent literature (http://www.ncbi.nlm.nih.gov/pubmed?term=%28%28AQP2%5BTIAB%5D%29%20OR%20%28aquaporin%202%5BTIAB%5D%29%29%20AND%20%28%28Genes%5BMH%5D%29%20OR%20%28Genetic%20Phenomena%5BMH%5D%29%29%20AND%20english%5Bla%5D%20AND%20human%5Bmh%5D%20AND%20%22last%201800%20days%22%5Bdp%5D)
- OMIM - Genetic disorder catalog (http://omim.org/entry/107777)
Research Resources - Tools for researchers
- Atlas of Genetics and Cytogenetics in Oncology and Haematology (http://atlasgeneticsoncology.org/Genes/GC_AQP2.html)
- HGNC Gene Family: Aquaporins (http://www.genenames.org/cgi-bin/genefamilies/set/305)
- HGNC Gene Symbol Report (http://www.genenames.org/cgi-bin/gene_symbol_report?q=data/hgnc_data.php&hgnc_id=634)
- NCBI Gene (http://www.ncbi.nlm.nih.gov/gene/359)
What other names do people use for the AQP2 gene or gene products?
- ADH water channel
- collecting duct water channel protein
- water-channel aquaporin 2
- water channel protein for renal collecting duct
See How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.
What glossary definitions help with understanding AQP2?
cell membrane ;
collecting duct ;
You may find definitions for these and many other terms in the Genetics Home Reference
- Deen PM, Verdijk MA, Knoers NV, Wieringa B, Monnens LA, van Os CH, van Oost BA. Requirement of human renal water channel aquaporin-2 for vasopressin-dependent concentration of urine. Science. 1994 Apr 1;264(5155):92-5. (http://www.ncbi.nlm.nih.gov/pubmed/8140421?dopt=Abstract)
- Knoers NV, Deen PM. Molecular and cellular defects in nephrogenic diabetes insipidus. Pediatr Nephrol. 2001 Dec;16(12):1146-52. Review. (http://www.ncbi.nlm.nih.gov/pubmed/11793119?dopt=Abstract)
- Kuwahara M, Iwai K, Ooeda T, Igarashi T, Ogawa E, Katsushima Y, Shinbo I, Uchida S, Terada Y, Arthus MF, Lonergan M, Fujiwara TM, Bichet DG, Marumo F, Sasaki S. Three families with autosomal dominant nephrogenic diabetes insipidus caused by aquaporin-2 mutations in the C-terminus. Am J Hum Genet. 2001 Oct;69(4):738-48. Epub 2001 Aug 30. (http://www.ncbi.nlm.nih.gov/pubmed/11536078?dopt=Abstract)
- Loonen AJ, Knoers NV, van Os CH, Deen PM. Aquaporin 2 mutations in nephrogenic diabetes insipidus. Semin Nephrol. 2008 May;28(3):252-65. doi: 10.1016/j.semnephrol.2008.03.006. Review. (http://www.ncbi.nlm.nih.gov/pubmed/18519086?dopt=Abstract)
- Marr N, Bichet DG, Hoefs S, Savelkoul PJ, Konings IB, De Mattia F, Graat MP, Arthus MF, Lonergan M, Fujiwara TM, Knoers NV, Landau D, Balfe WJ, Oksche A, Rosenthal W, Müller D, Van Os CH, Deen PM. Cell-biologic and functional analyses of five new Aquaporin-2 missense mutations that cause recessive nephrogenic diabetes insipidus. J Am Soc Nephrol. 2002 Sep;13(9):2267-77. (http://www.ncbi.nlm.nih.gov/pubmed/12191971?dopt=Abstract)
- NCBI Gene (http://www.ncbi.nlm.nih.gov/gene/359)
- Noda Y, Sohara E, Ohta E, Sasaki S. Aquaporins in kidney pathophysiology. Nat Rev Nephrol. 2010 Mar;6(3):168-78. doi: 10.1038/nrneph.2009.231. Epub 2010 Jan 26. Review. (http://www.ncbi.nlm.nih.gov/pubmed/20101255?dopt=Abstract)
- Robben JH, Knoers NV, Deen PM. Cell biological aspects of the vasopressin type-2 receptor and aquaporin 2 water channel in nephrogenic diabetes insipidus. Am J Physiol Renal Physiol. 2006 Aug;291(2):F257-70. Review. (http://www.ncbi.nlm.nih.gov/pubmed/16825342?dopt=Abstract)
The resources on this site should not be used as a substitute for
professional medical care or advice. Users seeking information about
a personal genetic disease, syndrome, or condition should consult with a qualified
See How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.