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Sialic Acid Storage Disorder (Salla Disease) via the SLC17A5 Gene

Summary and Pricing

Test Method

Sequencing and CNV Detection via NextGen Sequencing using PG-Select Capture Probes
Test Code Test Copy GenesTest CPT Code Gene CPT Codes Copy CPT Codes Base Price
SLC17A5 81479 81479,81479 $990
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
7823SLC17A581479 81479,81479 $990 Order Options and Pricing

Pricing Comments

Testing run on PG-select capture probes includes CNV analysis for the gene(s) on the panel but does not permit the optional add on of exome-wide CNV analysis. Any of the NGS platforms allow reflex to other clinically relevant genes, up to whole exome or whole genome sequencing depending upon the base platform selected for the initial test.

An additional 25% charge will be applied to STAT orders. STAT orders are prioritized throughout the testing process.

This test is also offered via a custom panel (click here) on our exome or genome backbone which permits the optional add on of exome-wide CNV or genome-wide SV analysis.

Turnaround Time

3 weeks on average for standard orders or 2 weeks on average for STAT orders.

Please note: Once the testing process begins, an Estimated Report Date (ERD) range will be displayed in the portal. This is the most accurate prediction of when your report will be complete and may differ from the average TAT published on our website. About 85% of our tests will be reported within or before the ERD range. We will notify you of significant delays or holds which will impact the ERD. Learn more about turnaround times here.

Targeted Testing

For ordering sequencing of targeted known variants, go to our Targeted Variants page.


Genetic Counselors


  • Li Fan, MD, PhD, FCCMG, FACMG

Clinical Features and Genetics

Clinical Features

Sialic acid storage disorder is an early onset neurodegenerative disease resulting from accumulation of free sialic acid within the lysosomes of most tissues, particularly in the brain. The spectrum of clinical phenotypes includes Salla disease and Infantile free sialic acid storage disease (Verheijen et al. 1999), as well as an intermediate form.

Salla disease is the mild form of sialic acid storage disorder, characterized by normal appearance at birth. Cerebellar ataxia and hypotonia occur during infancy, followed by progressive developmental delay in childhood, and psychomotor impairment, spasticity, ataxia, epileptic seizures, or intellectual disability in adulthood (Aula et al. 2000; Mochel et al. 2010).

Infantile free sialic acid storage disease (ISSD) or Salic acid storage disease, severe infantile type is the severe form of sialic acid storage disorder. Onset can occur in the embryo stage as hydrops fetalis, or at birth. The symptoms of ISSD include severe psychomotor retardation, dysostosis multiplex, and typical manifestations of lysosomal diseases such as severe developmental delay, coarse face, hepatosplenomegaly and cardiomegaly. Seizures are common. Patients have a shortened life span, and usually die before reaching 2 years (Verheijen et al. 1999; Froissart et al. 2005).


Sialic acid storage disorder is inherited in an autosomal recessive manner and caused by pathogenic variants in the SLC17A5 gene (solute carrier family 17, member 5) encoding the protein sialin. Sialin is a lysosomal membrane transport protein which transports free sialic acid out of lysosomes, or acts as a vesicular glutamic acid/aspartate transporter or maintains functional myelination in the brain (Miyaji et al. 2008; Wreden et al 2005; Morin et al. 2004; Sreedharan et al. 2010; Prolo et al. 2009). SLC17A5 is the only gene known to be responsible for Salla disease and Infantile free sialic acid storage disease.

Pathogenic variants in SLC17A5 gene include missense, nonsense, small deletions and insertions, and splice mutations, as well as large deletions and duplications. Most of SLC17A5 pathogenic variants cause defective or absent sialin. Of note, a single homozygous Finnish founder pathogenic variant (c.115C>T, p.Arg39Cys) presented in 91% of positive findings in Finnish patients. Variable expression has been noted in a family (Aula et al. 2000; Froissart et al. 2005; Paavola et al. 2015).

Clinical Sensitivity - Sequencing with CNV PG-Select

SLC17A5 is the only gene known to be involved with Salla disease and Infantile free sialic acid storage disease. A founder pathogenic variant (c.115C>T, p.Arg39Cys) is found in over 91% of Finnish patients (Aula et al. 2000). To date, there are about 30 other rare pathogenic SLC17A5 alleles that have been characterized at the molecular level (Human Gene Mutation Database).

Testing Strategy

This test provides full coverage of all coding exons of the SLC17A5 gene, plus ~10 bases of flanking noncoding DNA. We define full coverage as >20X NGS reads or Sanger sequencing.

Indications for Test

SLC17A5 sequencing is recommended for patients suspected to have Salla disease or Infantile free sialic acid storage disease. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in SLC17A5.


Official Gene Symbol OMIM ID
SLC17A5 604322
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT


  • Aula N. et al. 2000. American journal of human genetics. 67: 832-40. PubMed ID: 10947946
  • Froissart R. et al. 2005. Journal of medical genetics. 42: 829-36. PubMed ID: 15805149
  • Human Gene Mutation Database (Bio-base).
  • Miyaji T. et al. 2008. Proceedings of the National Academy of Sciences of the United States of America. 105: 11720-4. PubMed ID: 18695252
  • Mochel F. et al. 2010. Neurology. 74: 302-5. PubMed ID: 20101035
  • Morin P. et al. 2004. The EMBO journal. 23: 4560-70. PubMed ID: 15510212 PubMed ID: 15510212
  • Paavola LE. et al. 2012. Case reports in neurological medicine. 2012: 615721. PubMed ID: 23227378
  • Prolo LM. et al. 2009. The Journal of neuroscience : the official journal of the Society for Neuroscience. 29: 15355-65. PubMed ID: 20007460
  • Sreedharan S. et al. 2010. BMC genomics. 11: 17. PubMed ID: 20059771
  • Verheijen FW. et al. 1999. Nature genetics. 23: 462-5. PubMed ID: 10581036
  • Wreden CC. et al. 2005. The Journal of biological chemistry. 280: 1408-16. PubMed ID: 15516337


Ordering Options

We offer several options when ordering sequencing tests. For more information on these options, see our Ordering Instructions page. To view available options, click on the Order Options button within the test description.

myPrevent - Online Ordering

  • The test can be added to your online orders in the Summary and Pricing section.
  • Once the test has been added log in to myPrevent to fill out an online requisition form.
  • PGnome sequencing panels can be ordered via the myPrevent portal only at this time.

Requisition Form

  • A completed requisition form must accompany all specimens.
  • Billing information along with specimen and shipping instructions are within the requisition form.
  • All testing must be ordered by a qualified healthcare provider.

For Requisition Forms, visit our Forms page

If ordering a Duo or Trio test, the proband and all comparator samples are required to initiate testing. If we do not receive all required samples for the test ordered within 21 days, we will convert the order to the most effective testing strategy with the samples available. Prior authorization and/or billing in place may be impacted by a change in test code.

Specimen Types

Specimen Requirements and Shipping Details

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View Ordering Instructions

1) Select Test Method (Platform)

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2) Select Additional Test Options

No Additional Test Options are available for this test.

Note: acceptable specimen types are whole blood and DNA from whole blood only.
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