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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®

CA gene family

Reviewed May 2014

What are the CA genes?

Genes in the CA gene family provide instructions for making proteins called carbonic anhydrases. These proteins are found in different parts of the body, and although they carry out the same chemical reaction, they are involved in many different processes.

Carbonic anhydrases attach (bind) an atom of the metal zinc, which is integral to the proteins' function. For this reason, carbonic anhydrases are known as zinc metalloenzymes. These proteins carry out a chemical reaction called a hydration reaction. This reaction involves the molecules carbon dioxide and water and produces a negatively charged bicarbonate molecule (bicarbonate ion) and a positively charged hydrogen atom (known as a proton). Carbonic anhydrases can also carry out the reverse reaction, forming carbon dioxide and water from bicarbonate.

Carbon dioxide, bicarbonate, and protons are involved in many functions in the body; by regulating the levels of these substances, carbonic anhydrases play roles in several important processes, which can include the formation and breakdown (metabolism) of materials in the body, control of the relative acidity (pH) of cells, the release of salts (electrolytes) from tissues, and bone breakdown and growth.

Because the proteins produced from CA family genes are found in different regions of the body and are involved in a variety of processes, mutations in these genes can lead to diverse health conditions. The protein produced from the CA4 gene, called carbonic anhydrase IV (CA IV), is found in the blood vessels of the eyes and other organs. CA4 gene mutations lead to vision changes. Another CA family gene called CA12 provides instructions for making the CA XII protein, which is found in the sweat glands and other tissues. A mutation in this gene causes a condition called isolated hyperchlorhidrosis, the main feature of which is abnormally high levels of the salt sodium chloride (NaCl) in sweat.

Which genes are included in the CA gene family?

The HUGO Gene Nomenclature Committee (HGNC) provides an index of gene families ( and their member genes.

Genetics Home Reference summarizes the normal function and health implications of this member of the CA gene family: CA12.

What conditions are related to genes in the CA gene family?

Genetics Home Reference includes these conditions related to genes in the CA gene family:

  • isolated hyperchlorhidrosis

Where can I find additional information about the CA gene family?

You may find the following resources about the CA gene family helpful.

  • Biochemistry (fifth edition, 2002): Making a Fast Reaction Faster: Carbonic Anhydrases (

What glossary definitions help with understanding the CA gene family?

acidity ; atom ; bicarbonate ; breakdown ; Ca ; chloride ; gene ; metabolism ; molecule ; mutation ; NaCl ; pH ; protein ; proton ; sodium ; sodium chloride

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


These sources were used to develop the Genetics Home Reference summary for the CA gene family.

  • Aggarwal M, Boone CD, Kondeti B, McKenna R. Structural annotation of human carbonic anhydrases. J Enzyme Inhib Med Chem. 2013 Apr;28(2):267-77. doi: 10.3109/14756366.2012.737323. Epub 2012 Nov 9. Review. (
  • Supuran CT. Carbonic anhydrases--an overview. Curr Pharm Des. 2008;14(7):603-14. Review. (
  • Datta R, Waheed A, Bonapace G, Shah GN, Sly WS. Pathogenesis of retinitis pigmentosa associated with apoptosis-inducing mutations in carbonic anhydrase IV. Proc Natl Acad Sci U S A. 2009 Mar 3;106(9):3437-42. doi: 10.1073/pnas.0813178106. Epub 2009 Feb 11. (
  • Feldshtein M, Elkrinawi S, Yerushalmi B, Marcus B, Vullo D, Romi H, Ofir R, Landau D, Sivan S, Supuran CT, Birk OS. Hyperchlorhidrosis caused by homozygous mutation in CA12, encoding carbonic anhydrase XII. Am J Hum Genet. 2010 Nov 12;87(5):713-20. doi: 10.1016/j.ajhg.2010.10.008. Epub 2010 Oct 28. (


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 healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: May 2014
Published: September 1, 2015