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


Reviewed September 2010

What is the official name of the AGL gene?

The official name of this gene is “amylo-alpha-1, 6-glucosidase, 4-alpha-glucanotransferase.”

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

What is the normal function of the AGL gene?

The AGL gene provides instructions for making the glycogen debranching enzyme. This enzyme is involved in the breakdown of a complex sugar called glycogen, which is a major source of stored energy in the body. Glycogen is made up of several molecules of a simple sugar called glucose. Some glucose molecules are linked together in a straight line, while others branch off and form side chains. The glycogen debranching enzyme is involved in the breakdown of these side chains. The branched structure of glycogen makes it more compact for storage and allows it to break down more easily when it is needed for fuel.

The AGL gene provides instructions for making several different versions (isoforms) of the glycogen debranching enzyme. These isoforms vary by size and are active (expressed) in different tissues.

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

glycogen storage disease type III - caused by mutations in the AGL gene

Approximately 100 mutations in the AGL gene have been found to cause glycogen storage disease type III (also called GSDIII or Cori disease). Most of these mutations lead to a premature stop signal in the instructions for making the glycogen debranching enzyme, resulting in a nonfunctional enzyme. As a result, the side chains of glycogen molecules cannot be removed and abnormal, partially broken down glycogen molecules are stored within cells. A buildup of abnormal glycogen damages organs and tissues throughout the body, particularly the liver and muscles, leading to the signs and symptoms of GSDIII.

Mutations in the AGL gene can affect different isoforms of the enzyme, depending on where the mutations are located in the gene. For example, mutations that occur in a part of the AGL gene called exon 3 affect the isoform that is primarily expressed in the liver. These mutations almost always lead to GSD type IIIb, which is characterized by liver problems.

Where is the AGL gene located?

Cytogenetic Location: 1p21

Molecular Location on chromosome 1: base pairs 99,850,077 to 99,924,023

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

The AGL gene is located on the short (p) arm of chromosome 1 at position 21.

The AGL gene is located on the short (p) arm of chromosome 1 at position 21.

More precisely, the AGL gene is located from base pair 99,850,077 to base pair 99,924,023 on chromosome 1.

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

Where can I find additional information about AGL?

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

  • amylo-1, 6-glucosidase, 4-alpha-glucanotransferase
  • GDE
  • glycogen debrancher
  • glycogen debranching enzyme

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

What glossary definitions help with understanding AGL?

breakdown ; enzyme ; exon ; expressed ; gene ; glucose ; glycogen ; isoforms ; simple sugar

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


  • Cheng A, Zhang M, Okubo M, Omichi K, Saltiel AR. Distinct mutations in the glycogen debranching enzyme found in glycogen storage disease type III lead to impairment in diverse cellular functions. Hum Mol Genet. 2009 Jun 1;18(11):2045-52. doi: 10.1093/hmg/ddp128. Epub 2009 Mar 19. (
  • Endo Y, Horinishi A, Vorgerd M, Aoyama Y, Ebara T, Murase T, Odawara M, Podskarbi T, Shin YS, Okubo M. Molecular analysis of the AGL gene: heterogeneity of mutations in patients with glycogen storage disease type III from Germany, Canada, Afghanistan, Iran, and Turkey. J Hum Genet. 2006;51(11):958-63. Epub 2006 Sep 19. (
  • Frisbie JH, O'Connell DJ, Tow DE, Sasahara AA, Belko JS. Autologous radioiodinated fibrinogen, simplified. J Nucl Med. 1975 May;16(5):393-401. (
  • Lucchiari S, Pagliarani S, Salani S, Filocamo M, Di Rocco M, Melis D, Rodolico C, Musumeci O, Toscano A, Bresolin N, Comi GP. Hepatic and neuromuscular forms of glycogenosis type III: nine mutations in AGL. Hum Mutat. 2006 Jun;27(6):600-1. (
  • NCBI Gene (


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: September 2010
Published: February 8, 2016