Friedreich Ataxia (FXN) Repeat Expansion Test

Test Code
119
Orders for this test for patients residing in New York state cannot be accepted at this time.

Test Details


Test code:119
Type of disorder:Movement Disorders
Disease(s) tested for:Friedreich's Ataxia
Genes Included: FXN,
Profiles that contain this test:Ataxia, Complete Recessive Evaluation
Ataxia, Comprehensive Evaluation
Ataxia, Friedreich (FXN) Evaluation
Informed Consent Required:This test requires physician attestation that patient consent has been received
Patents:6,150,091

Technical Information


Clinical Significance:

Detects GAA triplet repeat expansion in the Frataxin gene

Typical Presentation: Neurodegenerative disorder characterized by progressive gait and limb ataxia with associated limb muscle weakness, absent lower limb reflexes, extensor plantar responses, dysarthria, and decreased vibratory sense and proprioception. Onset is usually in the first or second decade, before the end of puberty.

Methodology: Repeat Expansion Detection by PCR, Long Read Sequencing
Reference Range:Normal: <=33 GAA trinucleotide repeats

CPT Coding


The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.

CPT:81284(1)

Specimen Requirements


Please label each specimen tube with two forms of patient identification. These forms of identification must also appear on the requisition form.

Specimen Type:Whole blood
Specimen Stability:
Instructions:Higher blood volumes ensure adequate DNA quantity, which varies with WBC, specimen condition, and need for confirmatory testing. Patients, 0-3 years have higher WBC, yielding more DNA per mL of blood.

Shipping Considerations


Transport Temperature:Room temperature
Set-up/Analytic Time:14-28 days

Additional Resources

Letters of Medical Necessity

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