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SLC17A5

solute carrier family 17 member 5

The SLC17A5 gene provides instructions for producing the sialin protein, which is essential for transporting free sialic acid within cells and is associated with conditions like Infantile free sialic acid storage disease. SLC17A5 encodes the sialin protein, a lysosomal transporter responsible for moving free sialic acid.

Chromosome 6q13 Autosomal recessive HGNC:10933 Tier C
SLC17A5 6q13 p arm q arm 6

SLC17A5 is located on the long (q) arm of chromosome 6, at band 6q13. Arm ratio per GRCh38 - banding schematic.

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Clinical tests that include this

Carrier Screening panel
SLC17A5 is 1 of 1,008 genes on this panel
Expanded carrier screening for recessive and X-linked conditions

Overview

The SLC17A5 gene, also known as solute carrier family 17 member 5, plays a vital role in cellular metabolism by encoding the sialin protein. This protein functions as a transporter for free sialic acid, moving it out of lysosomes where it is produced during the breakdown of fats and proteins. Disruptions to this transport mechanism can lead to the accumulation of sialic acid within cells, affecting various physiological functions, particularly within the central nervous system.

What the gene does

The SLC17A5 gene directs the synthesis of sialin, a protein located on the membranes of lysosomes. Lysosomes are cellular compartments responsible for breaking down and recycling various molecules. Within these organelles, sialin's primary function is to transport free sialic acid from the lysosome into other parts of the cell. Sialic acid itself is generated through the degradation of fats and proteins and is important for cell communication and adhesion. When SLC17A5 function is impaired, free sialic acid can accumulate excessively within lysosomes, disrupting normal cellular processes and leading to specific health conditions.

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Chromosome location

The SLC17A5 gene is located on chromosome 6 at position 6q13. This genomic address specifies its exact position on the long arm of chromosome 6. The gene provides the blueprint for a protein that is 495 amino acids in length.

Protein structure

The sialin protein, encoded by the SLC17A5 gene, consists of 495 amino acids. Its structure includes a Disordered region at amino acids 1-24. Additionally, a Dileucine internalization motif is present at amino acids 22-23, which is typically involved in the internalisation and trafficking of membrane proteins.

Domain map · 495 amino acids
Dileucine internalization motif (22–23)Dileucine internalizat22–231~248495
Motif - short conserved sequence
🧬 Explore 3D structure on AlphaFold
UniProt:Q9NRA2Length:495 aaStructure:AlphaFold

Key variants

Variants within the SLC17A5 gene can alter the function of the sialin protein, impacting its ability to transport free sialic acid. These genetic changes can range from small point mutations to larger deletions, all potentially leading to a dysfunctional protein. The clinical impact of these variants can vary widely, from severe early-onset conditions to milder forms, depending on how significantly protein function is compromised.

The table below shows the top 10 pathogenic or likely-pathogenic variants currently classified in ClinVar for SLC17A5.
View all on ClinVar →

Sample of pathogenic variants

10 pathogenic / likely-pathogenic variants from ClinVar, ranked by review status (expert-panel-reviewed first). This is a sample; recurrent founder variants in a specific population may not appear here - see the full ClinVar listing via the link above.

Variant (HGVS) Protein change Classification Evidence Associated condition
c.1111+1G>A
single nucleotide variant
 - Pathogenic/Likely pathogenic ★★☆☆ Salla disease
c.1260-2A>C
single nucleotide variant
 - Pathogenic/Likely pathogenic ★★☆☆ Salla disease
c.1341del
Deletion
 p.Thr448fs Pathogenic ★★☆☆ Salla disease
c.684T>G
single nucleotide variant
 p.Tyr228Ter Pathogenic/Likely pathogenic ★★☆☆ Salla disease
c.699del
Deletion
 p.Phe233fs Pathogenic/Likely pathogenic ★★☆☆ Salla disease
c.738G>A
single nucleotide variant
 p.Trp246Ter Pathogenic/Likely pathogenic ★★☆☆ SLC17A5-related disorder
c.829C>T
single nucleotide variant
 p.Gln277Ter Pathogenic/Likely pathogenic ★★☆☆ Sialic acid storage disease, severe infantile type
c.903C>A
single nucleotide variant
 p.Tyr301Ter Pathogenic/Likely pathogenic ★★☆☆ Salla disease
c.979-1G>T
single nucleotide variant
 - Pathogenic/Likely pathogenic ★★☆☆ Salla disease
c.998del
Deletion
 p.Leu333fs Pathogenic/Likely pathogenic ★★☆☆ Salla disease

Evidence stars indicate ClinVar review status. Individual variant interpretation should always be performed by a qualified clinical laboratory - many variants remain classified as Variants of Uncertain Significance (VUS) pending more research.

Associated conditions

Pathogenic variants in the SLC17A5 gene are primarily associated with a group of conditions known as free sialic acid storage disorders. These include Infantile free sialic acid storage disease and Sialic acid storage disease (Salla). These conditions are inherited in an autosomal recessive pattern, meaning an individual must inherit two copies of a pathogenic variant, one from each parent, to be affected. The severity and presentation of these disorders can vary, often categorised into different forms based on the age of onset and the impact on the central nervous system.

Inheritance pattern

Conditions caused by pathogenic SLC17A5 variants typically follow autosomal recessive inheritance.

♀ Carrier parent 1 altered copy ♂ Carrier parent 1 altered copy Affected Carrier Carrier Unaffected Affected Carrier Unaffected Circles = females · Squares = males

When both parents are carriers, each child has a 25% chance of being affected, 50% of being a carrier, and 25% of being unaffected.

Carrier frequency by population How common is heterozygous SLC17A5 carrier status across ancestry groups?

UK clinical status

In the UK, the SLC17A5 gene is included in several NHS England Genomic Medicine Service national genomic test directories via PanelApp. It is rated 'green' for panels such as Ataxia and cerebellar anomalies - childhood onset, Foetal anomalies (R21), Inherited white matter disorders, Intellectual disability, Lysosomal storage disorder (R276), and Undiagnosed metabolic disorders, indicating strong evidence for its role in these conditions.

Green-listed
High evidence · clinically actionable in NHS testing
Included in NHS GMS signed-off panels
Fetal anomalies · R21 NHS GMS → Likely inborn error of metabolism · R98 NHS GMS → Lysosomal storage disorder · R276 NHS GMS → Skeletal dysplasia · R104 NHS GMS → Ataxia and cerebellar anomalies - childhood onset NHS GMS → DDG2P NHS GMS → Intellectual disability NHS GMS → White matter disorders and cerebral calcification - childhood onset NHS GMS →
NHS Genomic Medicine Service Jeen carrier screening

Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory

Frequently asked questions

What is the primary function of the SLC17A5 gene?

The SLC17A5 gene provides instructions for making the sialin protein, which transports free sialic acid out of lysosomes. This process is crucial for normal cellular metabolism and communication.

What conditions are associated with SLC17A5 variants?

Variants in the SLC17A5 gene are linked to free sialic acid storage disorders, including Infantile free sialic acid storage disease and Sialic acid storage disease (Salla). These are inherited in an autosomal recessive manner.

How is free sialic acid storage disorder inherited?

Free sialic acid storage disorder is inherited in an autosomal recessive pattern. This means an individual must inherit two copies of a pathogenic variant in the SLC17A5 gene, one from each parent, to develop the condition.

References

  1. Suwannarat P. Disorders of free sialic acid. Molecular genetics and metabolism. 2005. PMID: 15973781
  2. Aula N, Kopra O, Jalanko A. Sialin expression in the CNS implicates extralysosomal function in neurons. Neurobiology of disease. 2004. PMID: 15006695
  3. Morin P, Sagné C, Gasnier B. Functional characterization of wild-type and mutant human sialin. The EMBO journal. 2004. PMID: 15510212
  4. Eskelinen EL, Tanaka Y, Saftig P. At the acidic edge: emerging functions for lysosomal membrane proteins. Trends in cell biology. 2003. PMID: 12628346
  5. Mach L. Biosynthesis of lysosomal proteinases in health and disease. Biological chemistry. 2002. PMID: 12108539
  6. Adam MP, Bick S, Mirzaa GM. Free Sialic Acid Storage Disorder. 1993. PMID: 20301643
Educational content. This page is not medical or genetic advice, is not individually reviewed by a clinician for each reader, and should not replace a consultation with a qualified healthcare professional or genetic counsellor. If you are considering genetic testing or acting on a test result, book a consultation.
Data sources Last updated 11 October 2026. Content compiled from HGNC · MedlinePlus Genetics · ClinGen · Genomics England PanelApp · NHS National Genomic Test Directory · ClinVar · UniProt · AlphaFold .