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


Reviewed May 2014

What is the official name of the ALG6 gene?

The official name of this gene is “ALG6, alpha-1,3-glucosyltransferase.”

ALG6 is the gene's official symbol. The ALG6 gene is also known by other names, listed below.

What is the normal function of the ALG6 gene?

The ALG6 gene provides instructions for making an enzyme that is involved in a process called glycosylation. Glycosylation is a process by which sugar molecules (oligosaccharides) are attached to proteins and fats. Oligosaccharides are made up of many sugar molecules that are attached to one another in a stepwise process forming a complex chain. Glycosylation modifies proteins so they can perform a wider variety of functions. The enzyme produced from the ALG6 gene transfers a simple sugar called glucose to the growing oligosaccharide. Once the correct number of sugar molecules are linked together, the oligosaccharide is attached to a protein or fat.

How are changes in the ALG6 gene related to health conditions?

ALG6-congenital disorder of glycosylation - caused by mutations in the ALG6 gene

At least 20 mutations in the ALG6 gene have been found to cause ALG6-congenital disorder of glycosylation (ALG6-CDG, also known as congenital disorder of glycosylation type Ic). This condition typically leads to developmental delay, vision problems, seizures, and other signs and symptoms. Mutations in the ALG6 gene result in the production of an abnormal enzyme with reduced or no activity. A common mutation replaces the protein building block (amino acid) alanine with the amino acid valine at position 333 in the enzyme. This mutation, written as Ala333Val or A333V, results in an enzyme with reduced activity. Without a properly functioning enzyme, glycosylation cannot proceed normally, and oligosaccharides are incomplete. As a result, glycosylation is reduced or absent. The wide variety of signs and symptoms in ALG6-CDG are likely due to impaired glycosylation of proteins and fats that are needed for normal function in many organs and tissues, including the brain, eyes, and hormone-producing (endocrine) system.

Where is the ALG6 gene located?

Cytogenetic Location: 1p31.3

Molecular Location on chromosome 1: base pairs 63,367,590 to 63,438,562

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

The ALG6 gene is located on the short (p) arm of chromosome 1 at position 31.3.

The ALG6 gene is located on the short (p) arm of chromosome 1 at position 31.3.

More precisely, the ALG6 gene is located from base pair 63,367,590 to base pair 63,438,562 on chromosome 1.

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

Where can I find additional information about ALG6?

You and your healthcare professional may find the following resources about ALG6 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 ALG6 gene or gene products?

  • asparagine-linked glycosylation 6, alpha-1,3-glucosyltransferase homolog
  • asparagine-linked glycosylation 6 homolog (S. cerevisiae, alpha-1,3-glucosyltransferase)
  • asparagine-linked glycosylation 6 homolog (yeast, alpha-1,3-glucosyltransferase)
  • asparagine-linked glycosylation protein 6 homolog
  • dolichyl-P-Glc:Man(9)GlcNAc(2)-PP-dolichol alpha- 1->3-glucosyltransferase
  • dolichyl-P-Glc:Man9GlcNAc2-PP-dolichylglucosyltransferase
  • dolichyl-P-Glc:Man9GlcNAc2-PP-dolichyl glucosyltransferase
  • dolichyl pyrophosphate Man9GlcNAc2 alpha-1,3-glucosyltransferase
  • dolichyl pyrophosphate Man9GlcNAc2 alpha-1,3-glucosyltransferase precursor
  • dol-P-Glc:Man(9)GlcNAc(2)-PP-Dol alpha-1,3-glucosyltransferase
  • Man(9)GlcNAc(2)-PP-Dol alpha-1,3-glucosyltransferase

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

What glossary definitions help with understanding ALG6?

alanine ; amino acid ; asparagine ; congenital ; developmental delay ; enzyme ; gene ; glucose ; glycosylation ; hormone ; mutation ; oligosaccharides ; precursor ; protein ; simple sugar ; valine

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


  • Gene Review: Congenital Disorders of N-Linked Glycosylation Pathway Overview (
  • Grünewald S, Imbach T, Huijben K, Rubio-Gozalbo ME, Verrips A, de Klerk JB, Stroink H, de Rijk-van Andel JF, Van Hove JL, Wendel U, Matthijs G, Hennet T, Jaeken J, Wevers RA. Clinical and biochemical characteristics of congenital disorder of glycosylation type Ic, the first recognized endoplasmic reticulum defect in N-glycan synthesis. Ann Neurol. 2000 Jun;47(6):776-81. (
  • Imbach T, Burda P, Kuhnert P, Wevers RA, Aebi M, Berger EG, Hennet T. A mutation in the human ortholog of the Saccharomyces cerevisiae ALG6 gene causes carbohydrate-deficient glycoprotein syndrome type-Ic. Proc Natl Acad Sci U S A. 1999 Jun 8;96(12):6982-7. (
  • NCBI Gene (
  • Westphal V, Xiao M, Kwok PY, Freeze HH. Identification of a frequent variant in ALG6, the cause of Congenital Disorder of Glycosylation-Ic. Hum Mutat. 2003 Nov;22(5):420-1. (


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: May 2014
Published: February 8, 2016