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Giant Axonal Neuropathy via the GAN 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
GAN 81479 81479,81479 $990
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
11345GAN81479 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

Giant axonal neuropathy (OMIM 256850) is a slowly progressive neurodegenerative disorder of childhood onset affecting both the peripheral and central nervous systems. Mean age of onset among multiple affected families was reported to be 6-10 years of age and 2-7 years of age (Zemmouri et al. Neuromusc Disord 10:592- 598, 2000; Tazir et al. Neuromusc Disorder 19:270-274, 2009). The presenting clinical sign is often an unsteady gait in a child who began walking late. Peripheral motor and sensory neuropathy affects the lower limbs more than the upper limbs, and weakness tends to be diffuse. MRI detects cerebellar atrophy later in the course of the disease (Zemmouri et al. Neuromusc Disord 10:592-598, 2000). Motor nerve conduction velocities are normal or mildly reduced. Nerve biopsies in affected patients reveal axonal loss and the presence of giant axonal swellings filled with neurofilaments (Nalini et al. Eur J Med Genet 51:426-435, 2008). Other clinical features include characteristic kinky hair, long and curly eyelashes, variable degree of mental retardation, and seizures (Kuhlenbäumer and Timmerman. GeneReviews 2009).


Gigaxonin is present in the cytoskeleton and is essential for neuronal function and survival because of its interaction with ubiquitin-activating enzyme E1and subsequent involvement in protein degradation (Allen et al. Nature 438:224-228, 2005). Giant cell neuropathy is inherited as an autosomal recessive disorder (Bomont et al. Nature Genet 26:370-374, 2000). The largest class of pathogenic GAN gene variants is missense and nonsense variants. Splice site variants, small insertions and deletions, and gross deletions and insertions are also reported.

Clinical Sensitivity - Sequencing with CNV PGxome

Clinical sensitivity should be high in patients meeting clinical and histological criteria for this disorder. Analytical sensitivity is predicted to be less than 100% because gross copy number variants of the GAN gene are known.

Testing Strategy

This test provides full coverage of all coding exons of the GAN 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 childhood-onset peripheral motor and sensory neuropathy, involvement of the central nervous system, kinky hair, and nerve biopsies demonstrating giant axons. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in GAN.


Official Gene Symbol OMIM ID
GAN 605379
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT


Name Inheritance OMIM ID
Giant Axonal Neuropathy AR 256850


  • Allen et al. Nature 438:224-228, 2005 PubMed ID: 16227972
  • Bomont et al. Nature Genet 26:370-374, 2000 PubMed ID: 11062483
  • Kuhlenbäumer and Timmerman, GeneReviews 2009 PubMed ID: 20301315
  • Nalini et al. Eur J Med Genet 51:426-435, 2008 PubMed ID: 18595793
  • Tazir et al. Neuromusc Disorder 19:270-274, 2009 PubMed ID: 19231187
  • Zemmouri et al. Neuromusc Disord 10:592- 598, 2000 PubMed ID: 11053687


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

1) Select Test Method (Platform)

1) Select Test Type

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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