Glycogen Storage Disease Type 0 via the Glycogen Synthase 2 (GYS2) Gene

Summary and Pricing

Test Method

Exome Sequencing with CNV Detection
Test Code Test Copy GenesTest CPT Code Gene CPT Codes Copy CPT Codes Base Price
11833 GYS2 81479 81479,81479 $890 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
11833GYS281479 81479 $890 Order Options and Pricing

Pricing Comments

Our favored testing approach is exome based NextGen sequencing with CNV analysis. This will allow cost effective reflexing to PGxome or other exome based tests. However, if full gene Sanger sequencing is desired for STAT turnaround time, insurance, or other reasons, please see link below for Test Code, pricing, and turnaround time information. If the Sanger option is selected, CNV detection may be ordered through Test #600.

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

For Reflex to PGxome pricing click here.

The Sanger Sequencing method for this test is NY State approved.

For Sanger Sequencing click here.

Turnaround Time

18 days on average for standard orders or 14 days on average for STAT orders.

Once a specimen has started the testing process in our lab, the most accurate prediction of TAT will be displayed in the myPrevent portal as an Estimated Report Date (ERD) range. We calculate the ERD for each specimen as testing progresses; therefore the ERD range may differ from our published average TAT. View more about turnaround times here.

Targeted Testing

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

EMAIL CONTACTS

Genetic Counselors

Geneticist

Clinical Features and Genetics

Clinical Features

Glycogen storage disease type 0 (GSD0), or liver glycogen synthase deficiency, is a form of fasting hypoglycemia presenting in infancy or early childhood accompanied by high blood ketones and low alanine and lactate concentrations. Although feeding relieves symptoms, it often results in hyperglycemia and hyperlactatemia. Glycogen synthase activity is low or immeasurable in liver and hepatic glycogen content is decreased (Orho et al. 1998; Spiegel et al. 2007). Most cases can be managed by appropriate diet (Hicks et al. 2011). Glycogen storage disease type 0 is rare, but has probably been substantially underdiagnosed (Elpeleg 1999; Weinstein et al. 2006). It was recently reported that 2.4% of children in a group of 164 individuals with recurrent ketotic hypoglycemia had presumably pathogenic sequence variants in both copies of the GYS2 gene (Brown et al. 2015).

Genetics

GSD0 is caused by molecular defects in the GYS2 gene on chromosome 12, which encodes the glycogen synthase enzyme present in liver (Orho et al. 1998). GSD0 is an autosomal recessive disease. To date, nearly 20 pathogenic variants have been reported in the GYS2 gene. Of these, approximately half are missense, while the rest are nonsense and splice variants, small indels and deletions (Human Gene Mutation Database).

Clinical Sensitivity - Sequencing with CNV PGxome

Based on several literature reports that include a total of 15 patients, the clinical sensitivity of GYS2 gene sequencing for patients with true liver glycogen synthase deficiency is expected to be quite high. Of the 30 alleles in these patients, 28 were reported to carry GYS2 variants for a sensitivity of ~93% (Orho et al. 1998; Bachrach et al. 2002; Spiegel et al. 2007; Soggia et al. 2010; Brown et al. 2015; Szymanska et al. 2015). In a recent study of children with recurrent ketotic hypoglycemia, 2.4% of 164 patients were found to have two pathogenic variants in the GYS2 gene (Brown et al. 2015).

To date, no gross deletions or duplications have been reported in GYS2 (Human Gene Mutation Database).

Testing Strategy

This test provides full coverage of all coding exons of the GYS2 gene plus 10 bases of flanking noncoding DNA in all available transcripts along with other non-coding regions in which pathogenic variants have been identified at PreventionGenetics or reported elsewhere. We define full coverage as >20X NGS reads or Sanger sequencing.

Since this test is performed using exome capture probes, a reflex to any of our exome based tests is available (PGxome, PGxome Custom Panels).

Indications for Test

Candidates for this test are patients with symptoms consistent with GSD0 and the family members of patients who have known sequence variants. We will also sequence the GYS2 gene to determine carrier status.

Gene

Official Gene Symbol OMIM ID
GYS2 138571
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Disease

Name Inheritance OMIM ID
Glycogen Storage Disease 0, Liver AR 240600

Citations

  • Bachrach B.E. et al. 2002. The Journal of Pediatrics. 140: 781-3. PubMed ID: 12072888
  • Brown L.M. et al. 2015. Journal of Inherited Metabolic Disease. 38: 489-93. PubMed ID: 25070466
  • Elpeleg O.N. 1999. Journal of Pediatric Endocrinology & Metabolism. 12: 363-79. PubMed ID: 10821216
  • Hicks J. et al. 2011. Ultrastructural Pathology. 35: 183-96. PubMed ID: 21910565 PubMed ID: 21910565
  • Human Gene Mutation Database (Bio-base).
  • Orho M. et al. 1998. The Journal of Clinical Investigation. 102: 507-15. PubMed ID: 9691087
  • Soggia A.P. et al. 2010. Bmc Medical Genetics. 11: 3. PubMed ID: 20051115
  • Spiegel R. et al. 2007. Journal of Pediatric Endocrinology & Metabolism. 20: 1339-42. PubMed ID: 18341095
  • Szymanska E. et al. 2015. Molecular Genetics and Metabolism Reports. 4: 83-6. PubMed ID: 26937415
  • Weinstein D.A. et al. 2006. Molecular Genetics and Metabolism. 87: 284-8. PubMed ID: 16337419

Ordering/Specimens

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.

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


Specimen Types

Specimen Requirements and Shipping Details

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ORDER OPTIONS

View Ordering Instructions

1) Select Test Type


2) Select Additional Test Options

STAT and Prenatal Test Options are not available with Patient Plus.

No Additional Test Options are available for this test.

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