On this page:
Reviewed December 2015
What is the official name of the XDH gene?
The official name of this gene is “xanthine dehydrogenase.”
XDH is the gene's official symbol. The XDH gene is also known by other names, listed below.
Read more about gene names and symbols on the About page.
What is the normal function of the XDH gene?
The XDH gene provides instructions for making an enzyme called xanthine dehydrogenase. This enzyme is involved in the normal breakdown of purines, which are building blocks of DNA and its chemical cousin, RNA. Specifically, it carries out the final two steps in the process: the conversion of a molecule called hypoxanthine to another molecule called xanthine, and the conversion of xanthine to uric acid, a waste product that is normally excreted in urine and feces.
Xanthine dehydrogenase has been studied extensively because it can be involved in the production of molecules called superoxide radicals. Specifically, xanthine dehydrogenase is sometimes converted to another form called xanthine oxidase, which produces superoxide radicals. These molecules are byproducts of normal cell processes, and they must be broken down regularly to avoid damaging cells. Superoxide radicals are thought to play a role in many diseases, including heart disease and high blood pressure (hypertension).
Researchers suspect that xanthine dehydrogenase plays a role in milk production (lactation) in women. However, the enzyme's role in lactation is unclear.
How are changes in the XDH gene related to health conditions?
- hereditary xanthinuria - caused by mutations in the XDH gene
- At least 12 mutations in the XDH gene have been found to cause hereditary xanthinuria type I, a condition that most often affects the kidneys. These mutations reduce or eliminate the activity of xanthine dehydrogenase. As a result, the enzyme is not available to carry out the last two steps of purine breakdown. Because xanthine is not converted to uric acid, affected individuals have high levels of xanthine and very low levels of uric acid in their blood and urine. The excess xanthine can accumulate in the kidneys and other tissues. In the kidneys, xanthine forms tiny crystals that occasionally build up to create kidney stones. These stones can impair kidney function and ultimately cause kidney failure. Less commonly, xanthine crystals build up in the muscles, causing pain and cramping. In some people with hereditary xanthinuria, the condition does not cause any health problems.
Where is the XDH gene located?
Cytogenetic Location: 2p23.1
Molecular Location on chromosome 2: base pairs 31,334,309 to 31,414,749
(Homo sapiens Annotation Release 107, GRCh38.p2) (
The XDH gene is located on the short (p) arm of chromosome 2 at position 23.1.
More precisely, the XDH gene is located from base pair 31,334,309 to base pair 31,414,749 on chromosome 2.
See How do geneticists indicate the location of a gene? in the Handbook.
Where can I find additional information about XDH?
You and your healthcare professional may find the following resources about XDH 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 XDH gene or gene products?
- xanthine dehydrogenase/oxidase
- xanthine oxidoreductase
See How are genetic conditions and genes named? in the Handbook.
Where can I find general information about genes?
The Handbook provides basic information about genetics in clear language.
- What is DNA?
- What is a gene?
- How do genes direct the production of proteins?
- How can gene mutations affect health and development?
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding XDH?
allopurinol ; breakdown ; cell ; dehydrogenase ; DNA ; enzyme ; feces ; gene ; hereditary ;hypertension ; kidney ; kidney stones ; lactation ; molecule ; oxidase ; oxidoreductase ; purines ;RNA ; uric acid
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (7 links)
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