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Reviewed December 2015
What is the official name of the MOCOS gene?
The official name of this gene is “molybdenum cofactor sulfurase.”
MOCOS is the gene's official symbol. The MOCOS 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 MOCOS gene?
The MOCOS gene provides instructions for making an enzyme called molybdenum cofactor sulfurase. This enzyme is necessary for the function of two other enzymes, xanthine dehydrogenase and aldehyde oxidase. Xanthine dehydrogenase 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. Less is known about the function of aldehyde oxidase, although it appears to play a role in the breakdown (metabolism) of many different compounds.
Molybdenum cofactor sulfurase carries out a chemical reaction that adds sulfur to a molecule called the molybdenum cofactor. This molecule is required for xanthine dehydrogenase and aldehyde oxidase to be turned on (activated) and carry out their functions.
How are changes in the MOCOS gene related to health conditions?
- hereditary xanthinuria - caused by mutations in the MOCOS gene
- At least four mutations in the MOCOS gene have been found to cause hereditary xanthinuria type II, a condition that most often affects the kidneys. Most of these mutations change a single protein building block (amino acid) in molybdenum cofactor sulfurase. The effects of these mutations are not fully understood, but they likely alter the shape and function of the enzyme. If molybdenum cofactor sulfurase is unable to add sulfur to the molybdenum cofactor, xanthine dehydrogenase and aldehyde oxidase are not activated. The loss of aldehyde oxidase activity does not appear to cause any signs or symptoms. However, the loss of xanthine dehydrogenase activity prevents the conversion of xanthine to uric acid, leading to an accumulation of xanthine in the kidneys and other tissues. The excess xanthine can form tiny crystals that accumulate in the kidneys, occasionally leading to the formation of stones that 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 type II, the condition does not cause any health problems.
Where is the MOCOS gene located?
Cytogenetic Location: 18q12
Molecular Location on chromosome 18: base pairs 36,187,517 to 36,268,722
(Homo sapiens Annotation Release 107, GRCh38.p2) (
The MOCOS gene is located on the long (q) arm of chromosome 18 at position 12.
More precisely, the MOCOS gene is located from base pair 36,187,517 to base pair 36,268,722 on chromosome 18.
See How do geneticists indicate the location of a gene? in the Handbook.
Where can I find additional information about MOCOS?
You and your healthcare professional may find the following resources about MOCOS 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 MOCOS gene or gene products?
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 MOCOS?
aldehyde ; amino acid ; breakdown ; cofactor ; dehydrogenase ; DNA ; enzyme ; feces ; gene ;hereditary ; kidney ; metabolism ; molecule ; oxidase ; protein ; 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 (6 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