On this page, you will find information about genetic changes that were identified in a UDN participant.  

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Date of Report

Nov 27, 2017

Full Name

heparan-alpha-glucosaminide N-acetyltransferase

Chromosome 8 (8p11.2-p11.1)


The HGSNAT gene provides instructions to produce an enzyme (N-acetyltransferase) that is located in the lysosome, the part of the cell that helps to break down different types of molecules (Genetics Home Reference).

Database Links

GeneCards: GC08P043140

Genetics Home Reference: HGSNAT

NCBI Gene: 138050

OMIM: 610453

UniProtKB/Swiss-Prot: Q68CP4

Clinical Significance

Changes in the HGSNAT gene were identified in a UDN participant. The participant, a 40-year-old male with mucopolysaccharidosis type IIIC (Sanfilippo C) was found to carry the following genetic changes in the HGSNAT gene: c.1042G>A, c.1267G>T / p.V348M, p.G423W.

Inheritance Pattern Autosomal recessive
Position Chr8:43037317, Chr8:43047463
Transcript NM_152419
DNA Change c.1042G>A, c.1267G>T
Protein Change p.V348M, p.G423W

The participant’s parents became concerned with his development when he was about 3-4 years old. At this time, his speech was delayed and he was learning a bit slower than other children in school. He was able to graduate from high school, but had difficulty with college level work. Otherwise he was generally healthy and had normal development. He moved into a group home during a transitional period in his mid-twenties in which his frustration and inability to perform created job issues and strained family relationships.

At the age of 34, he had a trance-like episode with staring and drooling. Initially this was thought to be a seizure, but an EEG was normal. This episode marked the start of a significant decline where the participant lost his ability to process information and communicate complex ideas. He also started to experience a significant physical decline with poor coordination and difficulty with daily activities.

Some of his other features include:

  • Lack of insight
  • Attention deficit hyperactivity disorder
  • Depression
  • Involuntary muscle movements (dyskinesia)
  • Motor disorder due to brain damage (apraxia)
  • Poor coordination
  • Loss of brain tissue (cerebral atrophy)
  • Memory impairment
  • Reduced consciousness/confusion
  • Abnormality of eye movements
  • Language impairment (aphasia)
  • Repetitive vocalizations (echolalia)
  • Slurred speech
  • Shuffling walk (shuffling gait)
  • Obstructive sleep apnea
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