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ALG1 gene

ALG1 chitobiosyldiphosphodolichol beta-mannosyltransferase

Normal Function

The ALG1 gene provides instructions for making an enzyme that is involved in a process called glycosylation. During this process, complex chains of sugar molecules (oligosaccharides) are attached to proteins and fats (lipids). Glycosylation modifies proteins so they can fully perform their functions and modifies lipids so they can help cells interact with each other. Oligosaccharides are made up of many sugar molecules that are attached to one another in a stepwise process, forming a complex chain. The enzyme produced from the ALG1 gene transfers a simple sugar called mannose to growing oligosaccharides at a particular step in the formation of the chain. Once the correct number of sugar molecules are linked together, the oligosaccharide is attached to a protein or lipid.

Health Conditions Related to Genetic Changes

ALG1-congenital disorder of glycosylation

At least 15 mutations in the ALG1 gene have been found to cause ALG1-congenital disorder of glycosylation (ALG1-CDG). This condition typically leads to intellectual disability, delayed development, weak muscle tone (hypotonia), and other signs and symptoms that affect many body systems. Mutations in the ALG1 gene result in the production of an abnormal enzyme with little activity. The poorly functioning enzyme cannot add mannose to sugar chains efficiently, and the resulting oligosaccharides are often incomplete. Although the short oligosaccharides can be transferred to proteins and lipids, the process is not as efficient as with the full-length oligosaccharide. The wide variety of signs and symptoms in ALG1-CDG are likely due to impaired glycosylation of proteins and lipids that are needed for normal function of many organs and tissues.

More About This Health Condition

Other Names for This Gene

  • asparagine-linked glycosylation 1 homolog (yeast, beta-1,4-mannosyltransferase)
  • asparagine-linked glycosylation 1, beta-1,4-mannosyltransferase homolog
  • asparagine-linked glycosylation protein 1 homolog
  • beta-1,4 mannosyltransferase
  • beta-1,4-mannosyltransferase
  • chitobiosyldiphosphodolichol beta-mannosyltransferase
  • GDP-Man:GlcNAc2-PP-dolichol mannosyltransferase
  • GDP-mannose-dolichol diphosphochitobiose mannosyltransferase
  • hMat-1
  • HMAT1
  • HMT-1
  • HMT1
  • mannosyltransferase-1
  • Mat-1
  • MT-1

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

Scientific Articles on PubMed

Gene and Variant Databases


  • Dupre T, Vuillaumier-Barrot S, Chantret I, Sadou Yaye H, Le Bizec C, Afenjar A, Altuzarra C, Barnerias C, Burglen L, de Lonlay P, Feillet F, Napuri S, Seta N, Moore SE. Guanosine diphosphate-mannose:GlcNAc2-PP-dolichol mannosyltransferase deficiency (congenital disorders of glycosylation type Ik): five new patients and seven novel mutations. J Med Genet. 2010 Nov;47(11):729-35. doi: 10.1136/jmg.2009.072504. Epub 2010 Aug 2. Erratum In: J Med Genet. 2015 Mar;52(3):216. doi: 10.1136/jmedgenet-2009-072504corr1. Yaye, H S [corrected to Sadou Yaye, H]. Citation on PubMed
  • Jaeken J, Lefeber D, Matthijs G. Clinical utility gene card for: ALG1 defective congenital disorder of glycosylation. Eur J Hum Genet. 2015 Oct;23(10):1431. doi: 10.1038/ejhg.2015.9. Epub 2015 Feb 4. No abstract available. Citation on PubMed or Free article on PubMed Central
  • Morava E, Vodopiutz J, Lefeber DJ, Janecke AR, Schmidt WM, Lechner S, Item CB, Sykut-Cegielska J, Adamowicz M, Wierzba J, Zhang ZH, Mihalek I, Stockler S, Bodamer OA, Lehle L, Wevers RA. Defining the phenotype in congenital disorder of glycosylation due to ALG1 mutations. Pediatrics. 2012 Oct;130(4):e1034-9. doi: 10.1542/peds.2011-2711. Epub 2012 Sep 10. Citation on PubMed

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.