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Charcot-Marie-Tooth Disease and Distal Motor Neuropathy via the GBF1 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
15431 GBF1 81479 81479,81479 $890 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
15431GBF181479 81479,81479 $890 Order Options and Pricing

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 backbone).

Click here for costs to reflex to whole PGnome (if original test is on PGnome Sequencing backbone).

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

Charcot-Marie-Tooth disease (CMT), also known as hereditary motor and sensory neuropathy (HMSN) is a large group of inherited disorders of the peripheral nerves. The progressive degeneration of motor nerves results in weakness and atrophy of the distal muscles. The degeneration of sensory nerves leads to decreased sensation; tingling and numbness in the legs, feet, arms, and hands; and neuropathic pain. The age of onset varies from childhood to mid-adulthood. Symptoms usually begin with weakness and atrophy in the muscles of the legs and feet. As the disease progresses, weakness and atrophy of the muscles of the arms and hands may occur. CMT is heterogeneous in regard to symptoms, severity and progression rate. Although the disease may lead to disability and respiratory difficulty, life expectancy is usually unaffected. The most common symptoms include foot deformity, loss of balance, hammertoes, foot drop, frequent tripping and falls, and reduced manual dexterity (Bird. 2021. PubMed ID: 20301532). Diagnosis is based on clinical features, family history, neurological examination, and electromyography (EMG) and nerve conduction study (NCS) findings (Pareyson and Marchesi. 2009. PubMed ID: 19539237). CMT affects approximately 1 in 3,300 people (Bird. 2021. PubMed ID: 20301532).

GBF1-related neuropathies have been reported in four unrelated families to date (Mendoza-Ferreira et al. 2020. PubMed ID: 32937143). Clinical features include difficultly walking, foot deformities, foot drop, distal muscle weakness in upper and lower limbs, pes cavus deformity, mild sensory issues in some cases and NCS indicating axonal involvement. Age of onset ranged from mid-twenties to late fifties. Genetic testing may aid in establishing a differential diagnosis and may assist reproductive planning.

Genetics

Pathogenic variants in GBF1 are associated with autosomal dominant CMT2 or hereditary distal motor neuropathy (Mendoza-Ferreira et al. 2020. PubMed ID: 32937143). To date, only missense and one nonsense variant have been reported in the GBF1 gene in 4 unrelated families. In two patients, the variant was found to occur de novo and in the other two families the variant was inherited. In one case the variant was inherited from a presumably unaffected parent, indicating that reduced penetrance or variable expressivity may be possible. No structural variants have been reported.

GBF1 encodes Golgi-specific brefeldin A-resistance guanine nucleotide exchange factor 1 which facilitates GDP-to-GTP exchange for members of the ARF family of small GTPases. GBF1 is involved in maintenance and functioning of the Golgi apparatus and mitochondrial migration and positioning. Primary fibroblasts from affected individuals showed marked Golgi fragmentation. Early development studies in murine embryos indicate that GBF1 is present in neuronal tissues and cells necessary for motor neuron pathology (Mendoza-Ferreira et al. 2020. PubMed ID: 32937143). GBF1 has been cited as a non-essential gene for growth of human tissue culture cells (Online Gene Essentiality).

Clinical Sensitivity - Sequencing with CNV PGxome

The clinical sensitivity is difficult to estimate as to date only a limited number of cases have been described in the literature (Mendoza-Ferreira et al. 2020. PubMed ID: 32937143). Analytical sensitivity should be high as almost all pathogenic variants reported to date are detectable by sequencing. 

Testing Strategy

This test is performed using Next-Gen sequencing with additional Sanger sequencing as necessary.

This test provides full coverage of all coding exons of the GBF1 gene plus 10 bases flanking noncoding DNA in all available transcripts in addition to 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

Candidates for this test are patients with a suspected intermediate form of Charcot-Marie-Tooth disease. Testing is also indicated for family members of patients who have a known pathogenic variant in the GBF1 gene.

Gene

Official Gene Symbol OMIM ID
GBF1 603698
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Disease

Name Inheritance OMIM ID

Citations

  • Bird. 2021. PubMed ID: 20301532
  • Mendoza-Ferreira et al. 2020. PubMed ID: 32937143
  • Online Gene Essentiality (OGEE).
  • Pareyson and Marchesi. 2009. PubMed ID: 19539237

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

PGxome (Exome) Sequencing Panel

PGnome (Genome) Sequencing Panel

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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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