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GYG1-Related Disorders via the GYG1 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
GYG1 81479 81479,81479 $990
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
8423GYG181479 81479,81479 $990 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.

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

Click here for costs to reflex to whole PGxome (if original test is on PGxome Sequencing platform).

Click here for costs to reflex to whole PGnome (if original test is on PGnome Sequencing platform).

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

For Sanger Sequencing click here.

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


  • Maxime Cadieux-Dion, PhD

Clinical Features and Genetics

Clinical Features

Glycogen Storage Disease Type XV (GSD XV) and Polyglucosan Body Myopathy Type 2 (PGBM2) are rare, allelic disorders caused by a deficiency of the glycogenin-1 protein, which is encoded by the GYG1 gene. To date, only one individual has been reported with GSD XV (Moslemi et al. 2010). This patient presented in the third decade of life with cardiomyopathy and muscle weakness associated with a profound depletion of glycogen in skeletal muscle. There was some suspicion that the onset of the myopathic features may have been in childhood.

More commonly, variants in the GYG1 gene have been reported to be associated with PGBM2. These patients present with muscle weakness without cardiomyopathy. The age of onset and severity are variable, although the myopathy has been reported to be progressive in nearly all patients. Serum creatine kinase (CK) levels have been reported to be slightly elevated in some patients. In all PGBM2 patients, partially amylase-resistant periodic acid-Schiff (PAS)-positive inclusions have been detected in a portion of muscle fibers, with normal glycogen detected in the remaining fibers. In many of the patients, the inclusions have been confirmed via electron microscopy to be polyglucosan bodies (Malfatti et al. 2014; Fanin et al. 2015; Akman et al. 2016). Polyglucosan bodies are accumulations or abnormally structured glycogen that are poorly branched and may be less spherical than normal glycogen granules.


Both GSD Type XV and PGBM2 are autosomal recessive disorders. Pathogenic variants in the GYG1 gene are the only known cause of both of these disorders. To date, nearly 10 different causative variants have been reported in a total of 16 patients. The most commonly reported variant is defined as c.143+3G>C, which has been shown to result in the skipping of exon 2 (Malfatti et al. 2014). This variant has been reported in the homozygous or compound heterozygous state in approximately two-thirds of patients. The remaining variants appear to be private, and include missense, nonsense, frameshift and other splice variants, and are spread throughout the gene (Human Gene Mutation Database).

The GYG1 gene encodes the protein glycogenin-1, which is necessary for the initiation of glycogen synthesis in muscle tissues. Autoglucosylation of glycogenin results in the formation of a short primer for glycogen synthesis, containing approximately 10 glucose residues. After the primer is generated, glycogen elongation and branching is catalyzed by glycogen synthase and glycogen branching enzyme (Moslemi et al. 2010; Chen et al. 2014).

Clinical Sensitivity - Sequencing with CNV PGxome

Clinical sensitivity of this test is expected to be high as, to date, all identified patients have been found to have two pathogenic variants detectable via direct sequencing, suggesting a clinical sensitivity near 100% (Moslemi et al. 2010; Malfatti et al. 2014; Fanin et al. 2015; Akman et al. 2016).

Testing Strategy

This test provides full coverage of all coding exons of the GYG1 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. PGnome panels typically provide slightly increased coverage over the PGxome equivalent. PGnome sequencing panels have the added benefit of additional analysis and reporting of deep intronic regions (where applicable).

Dependent on the sequencing backbone selected for this testing, discounted reflex testing to any other similar backbone-based test is available (i.e., PGxome panel to whole PGxome; PGnome panel to whole PGnome).

Indications for Test

Patients with clinical features of GSD XV or PGBM2 are candidates for this test, particularly if amylase-resistant PAS-positive inclusions suggestive of polyglucosan bodies have been identified on a muscle biopsy. Family members of patients known to have GYG1 variants are also good candidates, and we will also sequence the GYG1 gene to determine carrier status.


Official Gene Symbol OMIM ID
GYG1 603942
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT


  • Akman H.O. et al. 2016. Neuromuscular Disorders : Nmd. 26: 16-20. PubMed ID: 26652229
  • Chen Y., Kishnani P.S. and Koeberl D. 2014. Glycogen Storage Diseases. In: Valle D, Beaudet AL, Vogelstein B, et al., editors. New York, NY: McGraw-Hill. OMMBID.
  • Fanin M. et al. 2015. Neurology. Genetics. 1: e21. PubMed ID: 27066558
  • Human Gene Mutation Database (Bio-base).
  • Malfatti E. et al. 2014. Annals of Neurology. 76: 891-8. PubMed ID: 25272951
  • Moslemi A.R. et al. 2010. The New England Journal of Medicine. 362: 1203-10. PubMed ID: 20357282


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

PGxome (Exome) Sequencing Panel

PGnome (Genome) Sequencing Panel

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2) Select Additional Test Options

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