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MPZ-Related Neuropathies via the MPZ 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
MPZ 81405 81405,81479 $990
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
8677MPZ81405 81405,81479 $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.


Genetic Counselors


  • 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 regards to symptoms, severity and progression rate. Although the disease may lead to disability and respiratory difficulty, life expectancy is usually unaffected. Most common symptoms include foot deformity, loss of balance, hammertoes, foot drop, frequent tripping and falls, and reduced manual dexterity (Bird 2015). Diagnosis is based on clinical features, family history, neurological examination, and electromyography (EMG) and nerve conduction velocity (NCV) findings (Pareyson and Marchesi 2009). CMT affects approximately 1 in 3,300 people (Bird 2015).

MPZ genetic defects can cause CMT1B, Dejerine-Sottas syndrome, congenital hypomyelinating neuropathy, and CMT2I/CMT2J (Lupski and Garcia 2014). The variation in disease presentation typically correlates with NCV findings. Very slow NCVs are seen in patients with severe, early onset disease and a later onset, mild phenotype is observed in those with near-normal NCV (Bird 2015). CMT2 caused by MPZ pathogenic variants has also been reported in some families with differing onset and presentation, including many of the features listed above. The axonal forms of CMT caused by MPZ, may also present with hearing loss and pupillary abnormalities (Bird 2015; Siskind et al. 2013).


Pathogenic variants in MPZ commonly cause autosomal dominant CMT1B (Bird 2015). However, more severe neuropathies such as Dejerine-Sottas syndrome and congenital hypomyelinating neuropathy are also caused by MPZ genetic defects and can exhibit both autosomal dominant and recessive inheritance (McMillan et al. 2010). CMT2I and CMT2J are axonal forms of CMT also caused by pathogenic variants in MPZ (Auer-Grumbach et al. 2003). The MPZ gene has 6 coding exons that encode myelin protein-zero (MPZ) which is the major structural protein of peripheral myelin (Lupski and Garcia 2014). This protein accounts for greater than 50% of the protein present in the sheath of peripheral nerves. MPZ is expressed in Schwann cells, and is not found in the central nervous system. Genetic defects of MPZ found to date include missense, nonsense, splicing and small deletion/insertions (Human Gene Mutation Database). A few large deletions/insertions involving the MPZ gene have also been reported.

Clinical Sensitivity - Sequencing with CNV PGxome

In three different large cohort studies, MPZ was found to be the causative gene in 4-5% of patients with a clinical diagnosis of CMT (Rossor et al. 2013; DiVincenzo et al. 2014; Fridman et al. 2015). CMT1B represents about 6%-10% of CMT1 cases (Mandich et al. 2009). It is considered the fourth most common type of CMT (Siskind et al. 2013). Analytical sensitivity should be high since the vast majority of reported variants are detectable by sequencing.

Testing Strategy

This test provides full coverage of all coding exons of the MPZ 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

Candidates for this test are patients with Charcot-Marie-Tooth disease, specifically those with slow NCV indicating a demyelinating CMT1. Testing is also indicated for family members of patients who have known pathogenic variants in the MPZ gene. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in MPZ.


Official Gene Symbol OMIM ID
MPZ 159440
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Related Tests

Charcot-Marie-Tooth (CMT) - Axonal Neuropathy Panel
Charcot-Marie-Tooth (CMT) - Comprehensive Panel
Charcot-Marie-Tooth (CMT) - Demyelinating Neuropathy Panel


  • Auer-Grumbach M. et al. 2003. Neurology. 61: 1435-7. PubMed ID: 14638973
  • Bird and Bird. 2015. PubMed ID: 20301532
  • Bird T.D. 2015. Charcot-Marie-Tooth Neuropathy Type 1. In: Pagon RA, Adam MP, Bird TD, Dolan CR, Fong C-T, Smith RJ, and Stephens K, editors. GeneReviews™, Seattle (WA): University of Washington, Seattle. PubMed ID: 20301384
  • DiVincenzo C. et al. 2014. Molecular Genetics & Genomic Medicine. 2: 522-9. PubMed ID: 25614874
  • Fridman V. et al. 2015. Journal of Neurology, Neurosurgery, and Psychiatry. 86: 873-8. PubMed ID: 25430934
  • Human Gene Mutation Database (Bio-base).
  • Mandich P. et al. 2009. European Journal of Human Genetics. 17: 1129-34. PubMed ID: 19293842
  • McMillan H.J. et al. 2010. Neuromuscular Disorders 20: 725-9. PubMed ID: 20621479
  • Pareyson D., Marchesi C. 2009. The Lancet Neurology. 8: 654–67. PubMed ID: 19539237
  • Rossor Alexander M. et al. 2013. Nature Reviews Neurology. 9: 562-571. PubMed ID: 24018473
  • Siskind C.E. et al. 2013. Journal of Genetic Counseling. 22: 422-36. PubMed ID: 23604902


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