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Congenital Myasthenic Syndrome via the GFPT1 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
4873 GFPT1 81479 81479,81479 $640 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
4873GFPT181479 81479(x2) $640 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.

Turnaround Time

18 days on average for standard orders or 13 days 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

Congenital myasthenic syndromes (CMS) are disorders of the neuromuscular junction resulting from defects in presynaptic, synaptic, or postsynaptic proteins. Clinically, a limb-girdle pattern of muscle involvement makes DOK7, AGRN, and GFPT1-related CMS unique from other CMS. Senderek et al. (Am J Hum Genet 88:162-172, 2011) found variants in the GFPT1 gene (OMIM 138292) in 13 families with autosomal recessive limb-girdle myasthenic syndrome with tubular aggregates (OMIM 610542). In vitro studies showed evidence for increased turnover or defective translation as an underlying pathological mechanism. Reduced numbers of acetylcholine receptors and decreased protein glycosylation were also noted (Senderek et al. 2011). Clinical symptoms, with onset during adolescence, include limb-girdle weakness and wasting with normal or slightly elevated serum CK levels (Rodolico et al. Neuromusc Disord 12:964-969, 2002). Muscle cramps and moderate exercise-induced fatigability are also documented (Sieb et al. Neuromusc Disord 6:115-119, 1996). Neither ptosis nor ophthalmoplegia are findings in GFPT1-related CMS. Electrophysiologic studies show decremental compound motor action potential responses in affected muscles, and single fiber EMG show impaired neuromuscular transmission with increased jitter (Rodolico et al. 2002). Muscle biopsies demonstrate 60-80 nm parallel subsarcolemmal tubular aggregates located predominantly in type 2 muscle fibers (Sieb et al. 1996). In contrast to DOK7-related CMS, tubular aggregates may be a universal finding in GFPT1-related CMS (Slater et al. Brain 129:2061-2076, 2006). Patients with limb-girdle myasthenic syndrome with tubular aggregates respond well to treatment with acetylcholinesterase inhibitors (Rodolico et al. 2002; Beeson et al. Science 313: 1975-1978, 2006).

Genetics

Abnormalities of proteins involved with neuromuscular transmission underlie familial limb-girdle myasthenic syndrome, congenital myasthenic syndromes, fetal akinesia deformation sequence, and multiple pterygium syndromes. These disorders, which may represent a phenotypic continuum of a single entity, are most often inherited in an autosomal recessive manner. Familial limb-girdle myasthenic syndrome with tubular aggregates due to GFPT1 variants is inherited as an autosomal recessive disorder (Senderek et al. 2011).

Clinical Sensitivity - Sequencing with CNV PG-Select

DOK7, AGRN, and GFPT1 variants are the only known cause of familial limb-girdle myasthenic syndrome. Clinical sensitivity should be high for patients meeting rigorous clinical, histopathological, and electrophysiological criteria.

Testing Strategy

This test provides full coverage of all coding exons of the GFPT1 gene, plus ~10 bases of flanking noncoding DNA. We define full coverage as >20X NGS reads or Sanger sequencing.

Indications for Test

Patients with a slowly progressive limb-girdle pattern of muscle weakness without facial involvement and tubular aggregates in muscle. Limb-girdle CMS patients who respond to AChE inhibitors. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in GFPT1.

Gene

Official Gene Symbol OMIM ID
GFPT1 138292
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Citations

  • Beeson, D., et.al. (2006). "Dok-7 mutations underlie a neuromuscular junction synaptopathy." Science 313(5795): 1975-8. PubMed ID: 16917026
  • Rodolico, C., et.al. (2002). "Limb-girdle myasthenia: clinical, electrophysiological and morphological features in familial and autoimmune cases." Neuromuscul Disord 12(10): 964-9. PubMed ID: 12467753
  • Senderek, J., et.al. (2011). "Hexosamine biosynthetic pathway mutations cause neuromuscular transmission defect." Am J Hum Genet 88(2): 162-72. PubMed ID: 21310273
  • Sieb, J. P., et.al. (1996). "An autosomal-recessive congenital myasthenic syndrome with tubular aggregates in a Libyan family." Neuromuscul Disord 6(2): 115-9. PubMed ID: 8664562
  • Slater, C. R., et.al. (2006). "Pre- and post-synaptic abnormalities associated with impaired neuromuscular transmission in a group of patients with PubMed ID: 16870884

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


Specimen Types

Specimen Requirements and Shipping Details

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ORDER OPTIONS

View Ordering Instructions

1) Select Test Method (Backbone)


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.
Total Price: $
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