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TAT gene

tyrosine aminotransferase

Normal Function

The TAT gene provides instructions for making a liver enzyme called tyrosine aminotransferase. This enzyme is the first in a series of five enzymes that work to break down the amino acid tyrosine, a protein building block found in many foods. Specifically, tyrosine aminotransferase converts tyrosine into a byproduct called 4-hydroxyphenylpyruvate. Continuing the process, 4-hydroxyphenylpyruvate is further broken down and ultimately smaller molecules are produced that are either excreted by the kidneys or used to produce energy or make other substances in the body.

Health Conditions Related to Genetic Changes


At least 22 TAT gene mutations have been found to cause tyrosinemia type II. This condition often affects the eyes, skin, and mental development. Most of these mutations change single DNA building blocks (base pairs) within the TAT gene. Research suggests that the altered TAT gene produces a tyrosine aminotransferase enzyme with reduced activity. Other mutations delete all or part of the TAT gene, eliminating enzyme activity. As a result of these mutations, tyrosine is not properly broken down. Tyrosine levels are elevated and some tyrosine is converted into other molecules that may be toxic to cells. It is unclear how impaired break down of tyrosine leads to the skin, eye, and intellectual problems that characterize tyrosinemia type II.

More About This Health Condition

Other Names for This Gene

  • L-tyrosine:2-oxoglutarate aminotransferase
  • tyrosine transaminase

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

Scientific Articles on PubMed

Catalog of Genes and Diseases from OMIM

Gene and Variant Databases


  • Bouyacoub Y, Zribi H, Azzouz H, Nasrallah F, Abdelaziz RB, Kacem M, Rekaya B, Messaoud O, Romdhane L, Charfeddine C, Bouziri M, Bouziri S, Tebib N, Mokni M, Kaabachi N, Boubaker S, Abdelhak S. Novel and recurrent mutations in the TAT gene in Tunisian families affected with Richner-Hanhart syndrome. Gene. 2013 Oct 15;529(1):45-9. doi: 10.1016/j.gene.2013.07.066. Epub 2013 Aug 13. Citation on PubMed
  • Mehere P, Han Q, Lemkul JA, Vavricka CJ, Robinson H, Bevan DR, Li J. Tyrosine aminotransferase: biochemical and structural properties and molecular dynamics simulations. Protein Cell. 2010 Nov;1(11):1023-32. doi: 10.1007/s13238-010-0128-5. Epub 2010 Dec 10. Citation on PubMed or Free article on PubMed Central
  • Sivaraman S, Kirsch JF. The narrow substrate specificity of human tyrosine aminotransferase--the enzyme deficient in tyrosinemia type II. FEBS J. 2006 May;273(9):1920-9. doi: 10.1111/j.1742-4658.2006.05202.x. Citation on PubMed

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.