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Myofibrillar Myopathy, Childhood Onset via the BAG3 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
BAG3 81479 81479,81479 $990
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
8577BAG381479 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.

EMAIL CONTACTS

Genetic Counselors

Geneticist

  • Angela Gruber, PhD

Clinical Features and Genetics

Clinical Features

Myofibrillar myopathy (MFM) refers to a genetically heterogeneous group of adult-onset disorders sharing a homogeneous morphological pattern. Stained with trichome, abnormal muscle fibers are seen containing hyaline structures and vacuoles that contain membrane fragments from disintegrated sarcomeric Z disc and myofibrils (Selcen et al. Brain 127:439-451, 2004). With electron microscopy, affected muscle fibers reveal progressive degeneration of myofibrils beginning at the Z-disk. Immunohistochemical staining of the structurally abnormal fibers reveals abnormal expression and accumulation of several proteins, including myotilin, desmin, alpha-B crystalline, dystrophin, and β-amyloid precursor protein (Selcen et al. 2004). Unlike typical MFM, which presents in adulthood, Bag3-associated MFM (OMIM 612954) presents in childhood with markedly progressive limb and axial weakness (Selcen et al. Ann Neurol 65:83-89, 2009). Among the three Bag3 patients thus far reported, all had elevated serum CK levels (3-, 6-, and 15-fold elevated), and all developed cardiomyopathy and respiratory insufficiency as teenagers. Two patients had rigid spines, and one had peripheral neuropathy. Muscle from affected individuals showed Z-disk degeneration and accumulation of granular debris and inclusions (Selcen et al. 2009).

Genetics

The BAG3 gene (OMIM 603883) encodes a Z-disc associated chaperone protein (Bag3) expressed in skeletal and cardiac muscle (Homma et al. Am J Pathol 169:761-773, 2006) that is involved with degrading misfolded and aggregated proteins (Takayama and Reed Nat Cell Biol 3:E237-E241, 2001). The reported cases of BAG3-associated myofibrillar myopathy have all been found to be heterozygous for a de novo p.Pro209Leu variant in exon 3 of the BAG3 gene, and to have an earlier and more severe clinical presentation than other forms of myofibrillar myopathy (Selcen et al. 2009).

Clinical Sensitivity - Sequencing with CNV PGxome

Of the documented inherited causes of myofibrillar myopathy, variants in the DES gene may be the single most common cause. However, the molecular basis of this disorder is heterogeneous and is known in only approximately 20% of cases. Selcen et al. found three cases of Bag3-associated MFM among 53 probands in whom variants in DES, CRYAB, TTID, ZASP, and FLNC were ruled-out. All three unrelated individuals were found to have a de novo p.Pro209Leu BAG3 variant.

Testing Strategy

This test provides full coverage of all coding exons of the BAG3 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 consistent with a childhood-onset, rapidly progressive muscular dystrophy with later involvement of cardiac muscle and respiratory distress, together with a muscle biopsy demonstrating characteristic immunohistochemical and ultrastructural features of myofibrillar myopathy.

Gene

Official Gene Symbol OMIM ID
BAG3 603883
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Disease

Name Inheritance OMIM ID
Myofibrillar Myopathy, BAG3-Related AD 612954

Related Test

Name
Comprehensive Cardiology Panel

Citations

  • Homma, S., et.al. (2006). "BAG3 deficiency results in fulminant myopathy and early lethality." Am J Pathol 169(3): 761-73. PubMed ID: 16936253
  • Selcen D, Muntoni F, Burton BK, Pegoraro E, Sewry C, Bite AV, Engel AG. 2009. Mutation in BAG3 causes severe dominant childhood muscular dystrophy. Ann Neurol 65: 83-89. PubMed ID: 19085932
  • Selcen D, Ohno K, Engel AG. 2004. Myofibrillar myopathy: clinical, morphological and genetic studies in 63 patients. Brain 127(Pt 2): 439-451. PubMed ID: 14711882
  • Takayama, S., Reed, J. C. (2001). "Molecular chaperone targeting and regulation by BAG family proteins." Nat Cell Biol 3(10): E237-41. PubMed ID: 11584289

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

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View Ordering Instructions

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2) Select Additional Test Options

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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