Glycogen Storage Disease Type VI via the PYGL Gene
Summary and Pricing 
Test Method
Exome Sequencing with CNV Detection
| Test Code | Test Copy Genes | Test CPT Code | Gene CPT Codes Copy CPT Code | Base Price | |
|---|---|---|---|---|---|
| 9353 | PYGL | 81479 | 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. 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.
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.
Clinical Features and Genetics
Clinical Features
Glycogen storage disease type VI (GSD type VI; OMIM 232700), also known as Hers disease, results from deficiency in the liver form of glycogen phosphorylase. Symptoms of prominent hepatomegaly, greatly elevated liver glycogen, growth retardation, and mild to moderate fasting hypoglycemia and hyperketosis appear in early childhood. Symptoms often gradually subside with age. Liver phosphorylase activity is significantly reduced but is usually not completely absent. Reduced liver phosphorylase activity may be due to deficiencies in phosphorylase kinase (see GSD type IX). For more information see www.agsdus.org.
Genetics
GSD type VI is inherited in an autosomal recessive fashion. The PYGL gene located on chromosome 14 encodes the liver form of glycogen phosphorylase. Only six causative variants in PYGL have been reported to date (Chang et al. Hum Mol Genet 7:865-870, 1998; Burwinkel et al. Am J Hum Genet 62:785-791, 1998; and Tang et al. Mol Genet Metab 79:142-145, 2003). Three were missense, and three were splicing. GSD type VI is relatively common in the Mennonite population (~0.1%) with a known founder variant (Chang et al. 1998).
Clinical Sensitivity - Sequencing with CNV PGxome
Sensitivity of this test has not been reported.
Testing Strategy
This test provides full coverage of all coding exons of the PYGL 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 symptoms consistent with GSD type VI are candidates for this test. GSD type VI appears to be quite rare. Therefore, testing of one or more of the genes encoding the subunits of glycogen phosphorylase kinase (involved in the more common GSD type IX), especially in male patients, should be considered. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in PYGL.
Patients with symptoms consistent with GSD type VI are candidates for this test. GSD type VI appears to be quite rare. Therefore, testing of one or more of the genes encoding the subunits of glycogen phosphorylase kinase (involved in the more common GSD type IX), especially in male patients, should be considered. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in PYGL.
Gene
| Official Gene Symbol | OMIM ID |
|---|---|
| PYGL | 613741 |
| Inheritance | Abbreviation |
|---|---|
| Autosomal Dominant | AD |
| Autosomal Recessive | AR |
| X-Linked | XL |
| Mitochondrial | MT |
Disease
| Name | Inheritance | OMIM ID |
|---|---|---|
| Glycogen Storage Disease Type VI | AR | 232700 |
Citations
- Burwinkel, B., et.al. (1998). "Mutations in the liver glycogen phosphorylase gene (PYGL) underlying glycogenosis type VI." Am J Hum Genet 62(4): 785-91. PubMed ID: 9529348
- Chang S, Rosenberg MJ, Morton H, Francomano CA, Biesecker LG. 1998. Identification of a mutation in liver glycogen phosphorylase in glycogen storage disease type VI. Human molecular genetics 7: 865–870. PubMed ID: 9536091
- Tang, N. L., et.al. (2003). "A novel mutation (G233D) in the glycogen phosphorylase gene in a patient with hepatic glycogen storage disease and residual enzyme activity." Mol Genet Metab 79(2): 142-5. PubMed ID: 12809646
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.
- 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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ORDER OPTIONS
View Ordering Instructions1) Select Test Type
2) Select Additional Test Options
No Additional Test Options are available for this test.