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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 GenesTest CPT Code Gene CPT Codes Copy CPT Codes Base Price
7795 PYGM 81406 81406,81479 $990 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
7795PYGM81406 81406,81479 $990 Order Options and Pricing

Pricing Comments

This test is also offered via our exome backbone with CNV detection (click here). The exome-based test may be higher priced, but permits reflex to the entire exome or to any other set of clinically relevant genes.

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

Testing run on PG-Select capture probes does not include exome-wide CNV analysis. Reflex is available to PGxome or an exome-based panel, or you can use this gene list to create a custom panel (click here).

Click here for costs to reflex to whole PGxome.

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.

EMAIL CONTACTS

Genetic Counselors

Geneticist

  • Maxime Cadieux-Dion, PhD

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.

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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View Ordering Instructions

1) Select Test Method (Platform)


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.

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