Glycogen Storage Disease, Type V (McArdle Disease) via the PYGM Gene
Summary and Pricing 
Test Method
Sequencing and CNV Detection via NextGen Sequencing using PG-Select Capture Probes| Test Code | Test Copy Genes | Test CPT Code | Gene CPT Codes Copy CPT Code | Base Price | |
|---|---|---|---|---|---|
| 7795 | PYGM | 81406 | 81406,81479 | $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.
Clinical Features and Genetics
Clinical Features
Glycogen storage disease type V (GSDV; OMIM 232600), also known as McArdle disease, is characterized by exercise-induced muscle fatigue, pain, and cramps. Onset is usually in the second to third decade. Intense exercise can lead to rhabdomyolysis with concomitant myoglobinuria and renal failure. Patients have elevated serum creatine kinase activity. Severity is highly variable.
Genetics
GSDV is an autosomal recessive disorder. Defects in the PYGM gene encoding the muscle phosphorylase enzyme are the only known cause of GSDV. Roughly 65 different causative variants have been reported in PYGM (www.hgmd.org; Martin et al. Ann Neurol 50:574-581, 2001; Bruno et al. Hum Mut 27:718, 2006). The variants are missense, nonsense, splicing and frameshift and are located throughout the length of this compact gene. Two variants, p.Arg50* in exon 1 and p.Gly205Ser, in exon 5 are common among European patients. No genotype-phenotype connections have yet been made. Amino acid numbering differs among research groups; for example p.Arg50* is sometimes referred to as p.Arg49*. A few authors have reported muscle symptoms in carriers of PYGM variants (see for example Manfredi et al. J Neurol Sci 115:91-94, 1993, but see also Andersen et al. Neurol 67:716-718, 2006). Recently, Vladutiu et al. (Muscle Nerve 34:153-162, 2006) reported a much higher frequency of PYGM variant carriers among patients with adverse muscle side effects to statins than among control groups.
Clinical Sensitivity - Sequencing with CNV PG-Select
Two causative variants will apparently be identified in nearly all patients with absence of muscle phosphorylase activity (Martin et al. 2001). The sensitivity in patients who have not had a test for enzyme activity is unknown.
Testing Strategy
This test provides full coverage of all coding exons of the PYGM gene, plus ~10 bases of flanking noncoding DNA. We define full coverage as >20X NGS reads or Sanger sequencing.
Indications for Test
All patients with symptoms consistent with GSDV are candidates for this test. This includes individuals with exercise intolerance as well as those with exercise-induced rhabdomyolysis and myoglobinuria. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in PYGM.
All patients with symptoms consistent with GSDV are candidates for this test. This includes individuals with exercise intolerance as well as those with exercise-induced rhabdomyolysis and myoglobinuria. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in PYGM.
Gene
| Official Gene Symbol | OMIM ID |
|---|---|
| PYGM | 608455 |
| Inheritance | Abbreviation |
|---|---|
| Autosomal Dominant | AD |
| Autosomal Recessive | AR |
| X-Linked | XL |
| Mitochondrial | MT |
Disease
| Name | Inheritance | OMIM ID |
|---|---|---|
| Glycogen Storage Disease Type V | AR | 232600 |
Citations
- Andersen, S. T., et.al. (2006). "Do carriers of PYGM mutations have symptoms of McArdle disease?." Neurology 67(4): 716-8. PubMed ID: 16924035
- Bruno, C., et.al. (2006). "McArdle disease: the mutation spectrum of PYGM in a large Italian cohort." Hum Mutat 27(7): 718. PubMed ID: 16786513
- Manfredi, G., et.al. (1993). "Manifesting heterozygotes in McArdle PubMed ID: 8468596
- Martin, M. A., et.al. (2001). "Molecular heterogeneity of myophosphorylase deficiency (McArdle PubMed ID: 11706962
- Vladutiu, G. D., et.al. (2006). "Genetic risk factors associated with lipid-lowering drug-induced myopathies." Muscle Nerve 34(2): 153-62. PubMed ID: 16671104
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
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ORDER OPTIONS
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2) Select Additional Test Options
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