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


Reviewed August 2009

What is the official name of the OAT gene?

The official name of this gene is “ornithine aminotransferase.”

OAT is the gene's official symbol. The OAT gene is also known by other names, listed below.

What is the normal function of the OAT gene?

The OAT gene provides instructions for making the enzyme ornithine aminotransferase. This enzyme is active in the energy-producing centers of cells (mitochondria), where it helps break down a molecule called ornithine. Ornithine is involved in the urea cycle, which processes excess nitrogen (in the form of ammonia) that is generated when protein is broken down by the body.

In addition to its role in the urea cycle, ornithine participates in several reactions that help ensure the proper balance of protein building blocks (amino acids) in the body. This balance is important because a specific sequence of amino acids is required to build each of the many different proteins needed for the body's functions. The ornithine aminotransferase enzyme helps convert ornithine into another molecule called pyrroline-5-carboxylate (P5C). P5C can be converted into the amino acids glutamate and proline.

How are changes in the OAT gene related to health conditions?

gyrate atrophy of the choroid and retina - caused by mutations in the OAT gene

More than 60 OAT gene mutations have been found to cause gyrate atrophy of the choroid and retina (often shortened to gyrate atrophy). These mutations result in a reduced amount of functional ornithine aminotransferase enzyme. A shortage of this enzyme impedes the conversion of ornithine into P5C. As a result, excess ornithine accumulates in the blood (hyperornithinemia), and less P5C than normal is produced. It is not clear how these changes result in progressive vision loss and the other features sometimes associated with gyrate atrophy. Researchers have suggested that a deficiency of P5C may interfere with the function of the retina, the specialized light-sensitive tissue that lines the back of the eye. It has also been proposed that excess ornithine may suppress the production of a molecule called creatine. Creatine is needed for many tissues in the body to store and use energy properly. It is involved in providing energy for muscle contraction, and it is also important in nervous system functioning.

Where is the OAT gene located?

Cytogenetic Location: 10q26

Molecular Location on chromosome 10: base pairs 124,397,303 to 124,418,976

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBI (

The OAT gene is located on the long (q) arm of chromosome 10 at position 26.

The OAT gene is located on the long (q) arm of chromosome 10 at position 26.

More precisely, the OAT gene is located from base pair 124,397,303 to base pair 124,418,976 on chromosome 10.

See How do geneticists indicate the location of a gene? ( in the Handbook.

Where can I find additional information about OAT?

You and your healthcare professional may find the following resources about OAT helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the OAT gene or gene products?

  • DKFZp781A11155
  • HOGA
  • ornithine aminotransferase (gyrate atrophy)
  • ornithine aminotransferase precursor

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding OAT?

acids ; ammonia ; atrophy ; carboxylate ; choroid ; contraction ; creatine ; deficiency ; enzyme ; gene ; mitochondria ; molecule ; nervous system ; precursor ; proline ; protein ; retina ; tissue ; urea

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


  • Mashima YG, Weleber RG, Kennaway NG, Inana G. Genotype-phenotype correlation of a pyridoxine-responsive form of gyrate atrophy. Ophthalmic Genet. 1999 Dec;20(4):219-24. (
  • Mitchell GA, Brody LC, Looney J, Steel G, Suchanek M, Dowling C, Der Kaloustian V, Kaiser-Kupfer M, Valle D. An initiator codon mutation in ornithine-delta-aminotransferase causing gyrate atrophy of the choroid and retina. J Clin Invest. 1988 Feb;81(2):630-3. (
  • NCBI Gene (
  • Ohkubo Y, Ueta A, Ito T, Sumi S, Yamada M, Ozawa K, Togari H. Vitamin B6-responsive ornithine aminotransferase deficiency with a novel mutation G237D. Tohoku J Exp Med. 2005 Apr;205(4):335-42. (
  • Peltola KE, Näntö-Salonen K, Heinonen OJ, Jääskeläinen S, Heinänen K, Simell O, Nikoskelainen E. Ophthalmologic heterogeneity in subjects with gyrate atrophy of choroid and retina harboring the L402P mutation of ornithine aminotransferase. Ophthalmology. 2001 Apr;108(4):721-9. (


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: August 2009
Published: February 8, 2016