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URL of this page: https://medlineplus.gov/genetics/gene/slc17a5/

SLC17A5 gene

solute carrier family 17 member 5

Normal Function

The SLC17A5 gene provides instructions for producing a protein called sialin. This protein is located on the membranes of lysosomes, which are compartments in the cell that digest and recycle different types of molecules.

Sialin moves (transports) a molecule called free sialic acid to other parts of the cell. Sialic acid is produced when fats and proteins are broken down, and it plays an important role in cell communication and in the attachment of cells to one another (adhesion). Sialic acid is "free" when it is not attached (bound) to other molecules. 

Health Conditions Related to Genetic Changes

Free sialic acid storage disorder

Variants (also called mutations) in the SLC17A5 gene have been found to cause free sialic acid storage disorder (FSASD). FSASD is an inherited condition that primarily affects the brain and spinal cord (central nervous system). This condition is often divided into three forms based on the severity of the signs and symptoms. 

Some SLC17A5 gene variants impair the function of the sialin protein, while others prevent sialin from being produced. In a few cases, sialin is produced but cannot travel to the lysosomal membrane where it is needed.

Most SLC17A5 variants replace one protein building block (amino acid) in the sialin protein with another. A particular SLC17A5 variant is found primarily in people from Finland. People from Finland with the least severe form of FSASD (called Salla disease) typically have this variant in both copies of the SLC17A5 gene.

The severe form of FSASD is caused by SLC17A5 gene variants that greatly impair the function of sialin protein. Individuals who have one SLC17A5 gene with the Finnish Salla disease variant and one SLC17A5 gene with a variant that causes more severe disease are believed to have the intermediate form of the disorder.

SLC17A5 gene variants that impair or eliminate sialin activity cause free sialic acid to build up in the lysosomes. People with a larger amount of free sialic acid inside the lysosomes typically have more severe signs and symptoms of FSASD, but it is not known exactly how this buildup causes the characteristic features of FSASD.

More About This Health Condition

Other Names for This Gene

  • AST
  • ISSD
  • NSD
  • SD
  • SIALIN
  • SLD
  • solute carrier family 17 (acidic sugar transporter), member 5
  • solute carrier family 17, (sodium phosphate cotransporter), member 5

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

References

  • Adams D, Wasserstein M. Free Sialic Acid Storage Disorders. 2003 Jun 13 [updated 2020 Jan 23]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews(R) [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2024. Available from http://www.ncbi.nlm.nih.gov/books/NBK1470/ Citation on PubMed
  • Aula N, Kopra O, Jalanko A, Peltonen L. Sialin expression in the CNS implicates extralysosomal function in neurons. Neurobiol Dis. 2004 Mar;15(2):251-61. doi: 10.1016/j.nbd.2003.11.017. Citation on PubMed
  • Barmherzig R, Bullivant G, Cordeiro D, Sinasac DS, Blaser S, Mercimek-Mahmutoglu S. A New Patient With Intermediate Severe Salla Disease With Hypomyelination: A Literature Review for Salla Disease. Pediatr Neurol. 2017 Sep;74:87-91.e2. doi: 10.1016/j.pediatrneurol.2017.05.022. Epub 2017 Jun 1. Citation on PubMed
  • Eskelinen EL, Tanaka Y, Saftig P. At the acidic edge: emerging functions for lysosomal membrane proteins. Trends Cell Biol. 2003 Mar;13(3):137-45. doi: 10.1016/s0962-8924(03)00005-9. Citation on PubMed
  • Huizing M, Hackbarth ME, Adams DR, Wasserstein M, Patterson MC, Walkley SU, Gahl WA; FSASD Consortium. Free sialic acid storage disorder: Progress and promise. Neurosci Lett. 2021 Jun 11;755:135896. doi: 10.1016/j.neulet.2021.135896. Epub 2021 Apr 20. Citation on PubMed
  • Mach L. Biosynthesis of lysosomal proteinases in health and disease. Biol Chem. 2002 May;383(5):751-6. doi: 10.1515/BC.2002.078. Citation on PubMed
  • Morin P, Sagne C, Gasnier B. Functional characterization of wild-type and mutant human sialin. EMBO J. 2004 Nov 24;23(23):4560-70. doi: 10.1038/sj.emboj.7600464. Epub 2004 Oct 28. Citation on PubMed or Free article on PubMed Central
  • Suwannarat P. Disorders of free sialic acid. Mol Genet Metab. 2005 Jun;85(2):85-7. doi: 10.1016/j.ymgme.2005.04.005. No abstract available. 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.