GALNS gene

galactosamine (N-acetyl)-6-sulfatase

The GALNS gene provides instructions for producing an enzyme called N-acetylgalactosamine 6-sulfatase. This enzyme is located in lysosomes, which are compartments within cells that break down and recycle different types of molecules. N-acetylgalactosamine 6-sulfatase is involved in the breakdown of large sugar molecules called glycosaminoglycans (GAGs) or mucopolysaccharides. Specifically, this enzyme removes a chemical group known as a sulfate from a GAG called keratan sulfate. Keratan sulfate is particularly abundant in cartilage and the clear covering of the eye (cornea).

More than 148 mutations in the GALNS gene have been found to cause mucopolysaccharidosis type IV (MPS IV). Most of these mutations change single DNA building blocks (nucleotides) in the gene. All of the mutations that cause MPS IV reduce or eliminate the function of N-acetylgalactosamine 6-sulfatase.

The lack of N-acetylgalactosamine 6-sulfatase activity leads to the accumulation of keratan sulfate within lysosomes. Because keratan sulfate is predominantly found in cartilage and the cornea, the buildup of this substance causes skeletal abnormalities and cloudy corneas. Researchers believe that a buildup of GAGs may also cause the features of MPS IV by interfering with the functions of other proteins inside lysosomes and disrupting the movement of molecules inside the cell.

Cytogenetic Location: 16q24.3, which is the long (q) arm of chromosome 16 at position 24.3

Molecular Location: base pairs 88,813,734 to 88,856,970 on chromosome 16 (Homo sapiens Annotation Release 108, GRCh38.p7) (NCBI)

Cytogenetic Location: 16q24.3, which is the long (q) arm of chromosome 16 at position 24.3
  • chondroitinase
  • chondroitinsulfatase
  • FLJ17434
  • FLJ42844
  • FLJ98217
  • galactosamine (N-acetyl)-6-sulfate sulfatase
  • galactose-6-sulfate sulfatase
  • galNAc6S sulfatase
  • GAS
  • MPS4A
  • N-acetylgalactosamine-6-sulfatase
  • N-acetylgalactosamine-6-sulfatase precursor
  • N-acetylgalactosamine-6-sulfate sulfatase