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IDUA gene


Normal Function

The IDUA gene provides instructions for producing an enzyme called alpha-L-iduronidase, which is essential for the breakdown of large sugar molecules called glycosaminoglycans (GAGs). Through a process called hydrolysis, alpha-L-iduronidase uses water molecules to break down a molecule known as unsulfated alpha-L-iduronic acid, which is present in two GAGs called heparan sulfate and dermatan sulfate. Alpha-L-iduronidase is located in lysosomes, compartments within cells that digest and recycle different types of molecules.

Health Conditions Related to Genetic Changes

Mucopolysaccharidosis type I

More than 100 mutations in the IDUA gene have been found to cause mucopolysaccharidosis type I (MPS I). Mutations that change one DNA building block (nucleotide) are the most common. All mutations that cause MPS I reduce or completely eliminate the function of alpha-L-iduronidase. It usually cannot be determined whether a certain mutation will cause severe or attenuated MPS I; however, people who do not produce any alpha-L-iduronidase have the severe form of this disorder.

The lack of alpha-L-iduronidase enzyme activity leads to the accumulation of heparan sulfate and dermatan sulfate within the lysosomes. The buildup of these GAGs increases the size of the lysosomes, which is why many tissues and organs are enlarged in MPS I. Researchers believe that the accumulated GAGs may also interfere with the functions of other proteins inside the lysosomes and disrupt the movement of molecules inside the cell.

More About This Health Condition

Other Names for This Gene

  • alpha-L-iduronidase

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


  • Beesley CE, Meaney CA, Greenland G, Adams V, Vellodi A, Young EP, Winchester BG. Mutational analysis of 85 mucopolysaccharidosis type I families: frequency of known mutations, identification of 17 novel mutations and in vitro expression of missense mutations. Hum Genet. 2001 Nov;109(5):503-11. doi: 10.1007/s004390100606. Epub 2001 Oct 19. Citation on PubMed
  • Clarke LA. Mucopolysaccharidosis Type I. 2002 Oct 31 [updated 2024 Apr 11]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Bean LJH, Gripp KW, Amemiya A, editors. GeneReviews(R) [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2024. Available from Citation on PubMed
  • Muenzer J. The mucopolysaccharidoses: a heterogeneous group of disorders with variable pediatric presentations. J Pediatr. 2004 May;144(5 Suppl):S27-34. doi: 10.1016/j.jpeds.2004.01.052. No abstract available. Citation on PubMed
  • Pastores GM, Arn P, Beck M, Clarke JT, Guffon N, Kaplan P, Muenzer J, Norato DY, Shapiro E, Thomas J, Viskochil D, Wraith JE. The MPS I registry: design, methodology, and early findings of a global disease registry for monitoring patients with Mucopolysaccharidosis Type I. Mol Genet Metab. 2007 May;91(1):37-47. doi: 10.1016/j.ymgme.2007.01.011. Epub 2007 Mar 2. Citation on PubMed
  • Terlato NJ, Cox GF. Can mucopolysaccharidosis type I disease severity be predicted based on a patient's genotype? A comprehensive review of the literature. Genet Med. 2003 Jul-Aug;5(4):286-94. doi: 10.1097/01.GIM.0000078027.83236.49. Citation on PubMed
  • Vijay S, Wraith JE. Clinical presentation and follow-up of patients with the attenuated phenotype of mucopolysaccharidosis type I. Acta Paediatr. 2005 Jul;94(7):872-7. doi: 10.1111/j.1651-2227.2005.tb02004.x. Citation on PubMed

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