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

HGSNAT gene

The HGSNAT gene provides instructions for producing an enzyme essential for breaking down complex sugar molecules, and mutations in this gene are linked to mucopolysaccharidosis type III.

Normal Function

The HGSNAT gene provides instructions for producing an enzyme called heparan-alpha-glucosaminide N-acetyltransferase (often shortened to N-acetyltransferase). This enzyme is located in lysosomes, which are 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 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, and all reduce or eliminate the function of N-acetyltransferase.

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

Retinitis pigmentosa

The HGSNAT gene has also been associated with retinitis pigmentosa.

Other Names for This Gene

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

Frequently Asked Questions

Neurological decline usually begins between ages 3 and 6, with progressive speech loss, motor slowing, and cognitive regression. By adolescence, many patients experience severe intellectual disability, seizures, and loss of ambulation. Early recognition of these signs allows for timely supportive care.
MPS IIIC is suspected when infants present with developmental regression, coarse facial features, or organomegaly. Confirmation requires a urine GAG screen showing elevated heparan sulfate, followed by a leukocyte or fibroblast enzyme assay that demonstrates reduced HGSNAT activity. Genetic sequencing of the HGSNAT gene identifies pathogenic variants and confirms the diagnosis.
Enzyme replacement therapy is not yet available for MPS IIIC. However, hematopoietic stem cell transplantation has been explored in some cases, and substrate reduction therapy is under investigation. Gene therapy trials are also in early stages, aiming to deliver functional HGSNAT to affected cells. Patients should discuss experimental options with a specialized metabolic center.
ccumulation of partially degraded heparan sulfate in retinal cells can lead to progressive photoreceptor loss, manifesting as retinitis pigmentosa. Routine ophthalmologic evaluations—including visual field testing, electroretinography, and optical coherence tomography—should begin in early childhood and be repeated annually to monitor disease progression and guide low‑vision support.
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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