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

UGT gene family

Reviewed February 2012

What are the UGT genes?

The genes in the UDP glucuronosyltransferases (UGT) family provide instructions for making enzymes that perform a chemical reaction called glucuronidation. During this reaction, the UGT enzyme transfers a compound called glucuronic acid from a molecule called uridine diphosphate glucuronic acid (UDP-glucuronic acid) to one of a number of different substances.

There are three known groups of UGT genes in this family, UGT1, UGT2, and UGT3, each of which includes multiple genes. All of the UGT enzymes produced from these genes have a similar region that recognizes UDP-glucuronic acid. Another region of each protein recognizes the substance to which glucuronic acid will be transferred. Most UGT proteins can transfer glucuronic acid to a limited number of different substances.

Hundreds of different substances are glucuronidated by UGT enzymes, including bilirubin, a toxic substance produced when red blood cells are broken down; steroids such as testosterone and estrogen; and serotonin, an important hormone that transmits brain signals. UGT enzymes also glucuronidate certain drugs such as acetaminophen and morphine, and normal genetic variations in UGT genes can play a role in a person's response to these drugs. Glucuronidation makes the affected substances dissolvable in water, which allows them to be removed from the body.

Many UGT enzymes are found in the liver and intestines, and they can also be found in other body tissues, including the kidneys, stomach, brain, lungs, and skin.

Which genes are included in the UGT 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 UGT gene family: UGT1A1.

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

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

  • Crigler-Najjar syndrome
  • Gilbert syndrome
  • warfarin resistance

What glossary definitions help with understanding the UGT gene family?

bilirubin ; compound ; enzyme ; hormone ; molecule ; protein ; steroids ; stomach ; testosterone ; toxic

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 UGT gene family.

  • Flinders University: UDP Glucuronosyltransferase Homepage (
  • King CD, Rios GR, Green MD, Tephly TR. UDP-glucuronosyltransferases. Curr Drug Metab. 2000 Sep;1(2):143-61. Review. (
  • Owens IS, Basu NK, Banerjee R. UDP-glucuronosyltransferases: gene structures of UGT1 and UGT2 families. Methods Enzymol. 2005;400:1-22. Review. (
  • Mackenzie PI, Bock KW, Burchell B, Guillemette C, Ikushiro S, Iyanagi T, Miners JO, Owens IS, Nebert DW. Nomenclature update for the mammalian UDP glycosyltransferase (UGT) gene superfamily. Pharmacogenet Genomics. 2005 Oct;15(10):677-85. Review. (


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: February 2012
Published: February 8, 2016