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heparan-alpha-glucosaminide N-acetyltransferase

Normal Function

The HGSNAT gene provides instructions for producing an enzyme called heparan-alpha-glucosaminide N-acetyltransferase (which is often shortened to N-acetyltransferase). This enzyme is located in lysosomes, compartments within cells that digest and recycle different types of molecules. N-acetyltransferase is involved in the step-wise breakdown (degradation) of large molecules called glycosaminoglycans (GAGs). GAGs are composed of sugar molecules that are linked together to form a long string. To break down these large molecules, individual sugars are removed one at a time from one end of the molecule. N-acetyltransferase adds a molecule called an acetyl group to the sugar glucosamine in a subset of GAGs called heparan sulfate. This addition prepares the GAG for the next step in the degradation process.

Health Conditions Related to Genetic Changes

Mucopolysaccharidosis type III

At least 54 mutations in the HGSNAT gene have been found to cause mucopolysaccharidosis type IIIC (MPS IIIC). Most of these mutations change single DNA building blocks (nucleotides) in the gene. All of the mutations that cause MPS IIIC reduce or eliminate the function of N-acetyltransferase.

The lack of N-acetyltransferase activity disrupts the breakdown of heparan sulfate. As a result, partially broken down heparan sulfate accumulates within lysosomes. Researchers believe that the accumulation of GAGs interferes with the functions of other proteins inside the lysosomes and disrupts the normal functions of cells. It is unknown why the buildup of heparan sulfate mostly affects the central nervous system in MPS IIIC.

More About This Health Condition

Other Names for This Gene

  • acetyl coenzyme A:alpha-glucosaminide N-acetyltransferase
  • DKFZp686G24175
  • FLJ22242
  • FLJ32731
  • TMEM76
  • transmembrane protein 76

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

Scientific Articles on PubMed

Catalog of Genes and Diseases from OMIM

Gene and Variant Databases


  • Fan X, Zhang H, Zhang S, Bagshaw RD, Tropak MB, Callahan JW, Mahuran DJ. Identification of the gene encoding the enzyme deficient in mucopolysaccharidosis IIIC (Sanfilippo disease type C). Am J Hum Genet. 2006 Oct;79(4):738-44. doi: 10.1086/508068. Epub 2006 Aug 23. Citation on PubMed or Free article on PubMed Central
  • Feldhammer M, Durand S, Mrazova L, Boucher RM, Laframboise R, Steinfeld R, Wraith JE, Michelakakis H, van Diggelen OP, Hrebicek M, Kmoch S, Pshezhetsky AV. Sanfilippo syndrome type C: mutation spectrum in the heparan sulfate acetyl-CoA: alpha-glucosaminide N-acetyltransferase (HGSNAT) gene. Hum Mutat. 2009 Jun;30(6):918-25. doi: 10.1002/humu.20986. Citation on PubMed
  • Feldhammer M, Durand S, Pshezhetsky AV. Protein misfolding as an underlying molecular defect in mucopolysaccharidosis III type C. PLoS One. 2009 Oct 13;4(10):e7434. doi: 10.1371/journal.pone.0007434. Citation on PubMed or Free article on PubMed Central
  • Hrebicek M, Mrazova L, Seyrantepe V, Durand S, Roslin NM, Noskova L, Hartmannova H, Ivanek R, Cizkova A, Poupetova H, Sikora J, Urinovska J, Stranecky V, Zeman J, Lepage P, Roquis D, Verner A, Ausseil J, Beesley CE, Maire I, Poorthuis BJ, van de Kamp J, van Diggelen OP, Wevers RA, Hudson TJ, Fujiwara TM, Majewski J, Morgan K, Kmoch S, Pshezhetsky AV. Mutations in TMEM76* cause mucopolysaccharidosis IIIC (Sanfilippo C syndrome). Am J Hum Genet. 2006 Nov;79(5):807-19. doi: 10.1086/508294. Epub 2006 Sep 8. Citation on PubMed or Free article on PubMed Central
  • Ruijter GJ, Valstar MJ, van de Kamp JM, van der Helm RM, Durand S, van Diggelen OP, Wevers RA, Poorthuis BJ, Pshezhetsky AV, Wijburg FA. Clinical and genetic spectrum of Sanfilippo type C (MPS IIIC) disease in The Netherlands. Mol Genet Metab. 2008 Feb;93(2):104-11. doi: 10.1016/j.ymgme.2007.09.011. Epub 2007 Nov 19. Citation on PubMed
  • Valstar MJ, Ruijter GJ, van Diggelen OP, Poorthuis BJ, Wijburg FA. Sanfilippo syndrome: a mini-review. J Inherit Metab Dis. 2008 Apr;31(2):240-52. doi: 10.1007/s10545-008-0838-5. Epub 2008 Apr 4. 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.