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


Reviewed December 2008

What is the official name of the AGA gene?

The official name of this gene is “aspartylglucosaminidase.”

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

What is the normal function of the AGA gene?

The AGA gene provides instructions for producing an enzyme called aspartylglucosaminidase. This enzyme is active in lysosomes, which are structures inside cells that act as recycling centers. Within lysosomes, the enzyme helps break down complexes of sugar molecules (oligosaccharides) attached to certain proteins (glycoproteins). Specifically, this enzyme cuts glycoproteins between a protein building block (amino acid) called asparagine and a sugar molecule called N-acetylglucosamine. This cut is one of the last steps in breaking down a glycoprotein in the lysosome.

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

aspartylglucosaminuria - caused by mutations in the AGA gene

More than 30 mutations in the AGA gene have been found to cause aspartylglucosaminuria. Most of these mutations change one amino acid in aspartylglucosaminidase. One mutation found in 98 percent of people with this condition in Finland replaces the amino acid cysteine with the amino acid serine at position 163 in the enzyme (written as Cys163Ser or C163S). Many mutations, including C163S, disrupt the proper folding of aspartylglucosaminidase, resulting in an enzyme that cannot effectively break down glycoproteins. A buildup of glycoproteins seems to particularly affect nerve cells in the brain; loss of these cells causes a progressive decline in mental functioning and the other signs and symptoms of aspartylglucosaminuria.

Where is the AGA gene located?

Cytogenetic Location: 4q34.3

Molecular Location on chromosome 4: base pairs 177,430,774 to 177,442,503

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

The AGA gene is located on the long (q) arm of chromosome 4 at position 34.3.

The AGA gene is located on the long (q) arm of chromosome 4 at position 34.3.

More precisely, the AGA gene is located from base pair 177,430,774 to base pair 177,442,503 on chromosome 4.

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

Where can I find additional information about AGA?

You and your healthcare professional may find the following resources about AGA 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 AGA gene or gene products?

  • ASRG
  • glycosylasparaginase
  • N(4)-(beta-N-acetylglucosaminyl)-L-asparaginase
  • N4-(N-acetyl-beta-glucosaminyl)-L-asparagine amidase

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

What glossary definitions help with understanding AGA?

amino acid ; asparagine ; cysteine ; enzyme ; gene ; glycoproteins ; lysosome ; molecule ; mutation ; oligosaccharides ; protein ; serine

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


  • Aronson NN Jr. Aspartylglycosaminuria: biochemistry and molecular biology. Biochim Biophys Acta. 1999 Oct 8;1455(2-3):139-54. Review. (
  • NCBI Gene (
  • Saarela J, Laine M, Oinonen C, von Schantz C, Jalanko A, Rouvinen J, Peltonen L. Molecular pathogenesis of a disease: structural consequences of aspartylglucosaminuria mutations. Hum Mol Genet. 2001 Apr 15;10(9):983-95. (
  • Saarela J, Oinonen C, Jalanko A, Rouvinen J, Peltonen L. Autoproteolytic activation of human aspartylglucosaminidase. Biochem J. 2004 Mar 1;378(Pt 2):363-71. (


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: December 2008
Published: February 8, 2016