SCA1 (ATXN1) Repeat Expansion Test

Test Code

92903

CPT Codes
81178

Preferred Specimen

8 mL whole blood collected into two EDTA (lavender-top) tubes
Pediatric (0-3 years): 2 mL whole blood

Minimum Volume

6 mL • Pediatrics: 1 mL

Instructions

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

Note: 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.

Transport Temperature

Room temperature

Specimen Stability

Room temperature: 10 days
Refrigerated: 10 days
Frozen: Unacceptable

Methodology
Repeat Expansion Detection by Polymerase Chain Reaction

Setup Schedule

Set up: Varies; Report available: 14-21 days

Reference Range

Technical Results:
SfaNI Site Absent-Normal (≤35)
Borderline (36-38)
Positive (≥39)

SfaNI Site Present-Normal (≤44)
Positive (≥45)

Clinical Significance

Detects CAG triplet repeat expansion in the SCA1 gene. The usual clinical characteristics of the spinocerebellar ataxias are a slowly progressive incoordination of gait that is often associated with poor coordination of hands, speech, and eye movements.

Performing Laboratory
Athena Diagnostics, Inc.
200 Forest Street, 2nd Floor
Marlborough, MA 01752

The CPT Codes provided in this document 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 payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.