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GALNS gene

galactosamine (N-acetyl)-6-sulfatase

Normal Function

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).

Health Conditions Related to Genetic Changes

Mucopolysaccharidosis type IV

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.

More About This Health Condition

Other Names for This Gene

  • 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

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


  • Montano AM, Sukegawa K, Kato Z, Carrozzo R, Di Natale P, Christensen E, Orii KO, Orii T, Kondo N, Tomatsu S. Effect of 'attenuated' mutations in mucopolysaccharidosis IVA on molecular phenotypes of N-acetylgalactosamine-6-sulfate sulfatase. J Inherit Metab Dis. 2007 Oct;30(5):758-67. doi: 10.1007/s10545-007-0702-z. Epub 2007 Sep 17. Citation on PubMed
  • Tomatsu S, Montano AM, Lopez P, Trandafirescu G, Gutierrez MA, Oikawa H, Nishioka T, Vieira MB, Orii T, Noguchi A. Determinant factors of spectrum of missense variants in mucopolysaccharidosis IVA gene. Mol Genet Metab. 2006 Sep-Oct;89(1-2):139-49. doi: 10.1016/j.ymgme.2006.05.012. Epub 2006 Jul 11. Citation on PubMed
  • Tomatsu S, Montano AM, Nishioka T, Gutierrez MA, Pena OM, Tranda Firescu GG, Lopez P, Yamaguchi S, Noguchi A, Orii T. Mutation and polymorphism spectrum of the GALNS gene in mucopolysaccharidosis IVA (Morquio A). Hum Mutat. 2005 Dec;26(6):500-12. doi: 10.1002/humu.20257. Citation on PubMed

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.