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Charcot-Marie-Tooth Type 4D via the NDRG1 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
NDRG1 81479 81479,81479 $990
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
8119NDRG181479 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.


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; and 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 muscle 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. Diagnosis is based on clinical features, family history, neurological examination, and electromyography (EMG) and nerve conduction velocity (NCV) findings (Pareyson and Marchesi 2009; Bird 2015). CMT affects approximately 1 in 3,300 people.

Charcot-Marie-Tooth type 4D (CMT4D) (also referred to as hereditary and sensory neuropathy-Lom- HMSNL) is an autosomal recessive from of CMT that presents with early-onset peripheral neuropathy that progresses to severe disability in adulthood (Kalaydjieva et al. 2000). Patients present with muscle weakness and wasting, tendon areflexia, skeletal and foot deformities, sensory loss, severe reduction in nerve conduction velocities, and hearing loss in the second or third decade (Kalaydjieva et al. 2000; Hunter et al. 2003, Okamota et al. 2014).


Charcot-Marie-Tooth type 4D (CMT4D) is inherited in an autosomal recessive manner due to pathogenic variants in NDRG1, located on chromosome 8q24.3. NDRG1 encodes the N-myc downstream-regulated 1 protein which has been shown to function in many pathways including tumor suppression, metastasis inhibition, stress response, differentiation, and N-myc developmental regulation (Echaniz-Laguna et al. 2007). CMT4D is almost exclusively found in individuals of Romani ancestry who carry a common founder mutation referred to as c.442C>T, p.Arg148* (Kalaydjieva et al. 2000; Hunter et al. 2003). A splice variant and large duplication have also been reported in the NDRG1 gene (Hunter et al. 2003; Okamota et al. 2014).

Clinical Sensitivity - Sequencing with CNV PGxome

In a study of 104 patients with peripheral neuropathy in which common forms of CMT had been ruled out (negative for PMP22, MPZ, GJB1, and EGR2 variants), three were found to have a pathogenic variant in NDRG1 (2.9%) (Hunter et al. 2003).

Only one large duplication of the NRDG1 gene has been published to date; therefore, sensitivity of this test is uncertain (Okamoto et al. 2014).

Testing Strategy

This test provides full coverage of all coding exons of the NDRG1 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 a suspected demyelinating CMT that have had other common forms of CMT ruled out. Testing is also indicated for family members of patients who have known pathogenic variants in the NDRG1 gene. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in NDRG1.


Official Gene Symbol OMIM ID
NDRG1 605262
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT


Name Inheritance OMIM ID
Charcot-Marie-Tooth Disease, Type 4D AR 601455


  • Bird and Bird. 2015. PubMed ID: 20301532
  • Echaniz-Laguna A. et al. 2007. Neuromuscular Disorders : Nmd. 17: 163-8. PubMed ID: 17142040
  • Hunter M. et al. 2003. Human Mutation. 22: 129-35. PubMed ID: 12872253
  • Kalaydjieva L. et al. 2000. American Journal of Human Genetics. 67: 47-58. PubMed ID: 10831399
  • Okamoto Y. et al. 2014. Genetics in Medicine. 16: 386-94. PubMed ID: 24136616
  • Pareyson D., Marchesi C. 2009. The Lancet Neurology. 8: 65467. PubMed ID: 19539237


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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View Ordering Instructions

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2) Select Additional Test Options

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