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IDUA gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

IDUA gene

The IDUA gene provides instructions for producing the alpha-L-iduronidase enzyme, which is essential for breaking down complex sugar molecules in the body's cells.

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.

Other Names for This Gene

  • alpha-L-iduronidase
  • IDUA_HUMAN

Frequently Asked Questions

MPS I is an autosomal recessive disorder. Both biological parents are typically obligate, asymptomatic carriers who possess one mutated and one functional copy of the IDUA gene. With each subsequent pregnancy, there is a 25 percent chance of having an affected child, a 50 percent chance of having an asymptomatic carrier child, and a 25 percent chance of having a child with two unaffected copies of the gene. Genetic counseling and prenatal diagnostic testing (such as chorionic villus sampling or amniocentesis) are available.
ll three conditions represent a clinical continuum of mucopolysaccharidosis type I (MPS I) caused by variations in the IDUA gene. Hurler syndrome is the severe form, occurring when variations cause an absolute absence of alpha-L-iduronidase activity, resulting in early neurocognitive deterioration and systemic involvement. Scheie syndrome is the attenuated form, where residual enzyme activity allows for normal intellectual development and prolonged survival, with symptoms confined largely to joints, heart valves, and the eyes. Hurler-Scheie represents an intermediate phenotype.
Hematopoietic stem cell transplantation (HSCT) can deliver donor cells that produce functional alpha-L-iduronidase capable of crossing into the central nervous system through donor-derived microglial cells. If performed early (ideally before age two and prior to significant developmental delay), HSCT can halt or substantially slow cognitive deterioration, which intravenous enzyme replacement therapy cannot accomplish.
Newborn screening tests a dried blood spot via a heel prick to measure alpha-L-iduronidase enzyme activity. A screen showing reduced enzyme activity is not a definitive diagnosis; it triggers urgent confirmatory testing. This includes a quantitative repeat enzyme assay in isolated leukocytes, urinary glycosaminoglycan (GAG) analysis, and full sequencing of the IDUA gene to distinguish between pseudodeficiency, true pathogenic mutations, and carrier status.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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