Machado-Joseph Disease (MJD)/Spinocerebellar Ataxia Type 3 (SCA3) via the ATXN3 … see more Machado-Joseph Disease (MJD)/Spinocerebellar Ataxia Type 3 (SCA3) via the ATXN3 CAG Repeat Expansion  see less
GTR Test Accession: Help GTR000596301.1
Last updated in GTR: 2021-10-19
Last annual review date for the lab: 2024-05-20 LinkOut
At a Glance
Diagnosis; Mutation Confirmation; Pre-symptomatic; ...
Azorean disease
Genes (1): Help
ATXN3 (14q32.12)
Molecular Genetics - Targeted variant analysis: PCR with allele specific hybridization
Testing for the ATXN3 repeat expansion is recommended for individuals …
Not provided
Not provided
Ordering Information
Offered by: Help
PreventionGenetics, part of Exact Sciences
View lab's website
View lab's test page
Specimen Source: Help
Who can order: Help
  • Genetic Counselor
  • Health Care Provider
  • Licensed Physician
Test Order Code: Help
How to Order: Help
Please visit Lab website for details. Additional specimen types may be acceptable based on method. Please contact us about prenatal cases.
Order URL
Test service: Help
Clinical Testing/Confirmation of Mutations Identified Previously
    OrderCode: 13213
Test additional service: Help
Custom Prenatal Testing
    OrderCode: 990
Test development: Help
Test developed by laboratory (no manufacturer test name)
Informed consent required: Help
Pre-test genetic counseling required: Help
Post-test genetic counseling required: Help
Recommended fields not provided:
Conditions Help
Total conditions: 1
Condition/Phenotype Identifier
Test Targets
Genes Help
Total genes: 1
Gene Associated Condition Germline or Somatic Allele (Lab-provided) Variant in NCBI
Total methods: 1
Method Category Help
Test method Help
Targeted variant analysis
PCR with allele specific hybridization
Clinical Information
Test purpose: Help
Diagnosis; Mutation Confirmation; Pre-symptomatic; Risk Assessment; Screening
Target population: Help
Testing for the ATXN3 repeat expansion is recommended for individuals suspected of having MSCA3 (presentation of progressive cerebellar ataxia and variable findings such as pyramidal and extra-pyramidal signs, peripheral amyotrophy, generalized areflexia, progressive external ophthalmoplegia, facial and lingual muscle twitches, and bulging eyes). Testing is also recommended for individuals with … View more
Variant Interpretation:
What is the protocol for interpreting a variation as a VUS? Help
The PreventionGenetics protocol for interpreting sequence variants has been carefully developed over a period of 10 years. We are conservative in our interpretations. We do not label a variant as pathogenic or benign without conclusive evidence. Although we use a variety of software to assist us in interpretation, we rely … View more

Are family members with defined clinical status recruited to assess significance of VUS without charge? Help
Yes. Please visit our website for details at for Targeted variant tests.

Will the lab re-contact the ordering physician if variant interpretation changes? Help
Yes. Please visit our website for details
Recommended fields not provided:
Technical Information
Test Procedure: Help
This test is designed to only detect pathogenic expansions of a poly-glutamine CAG repeat in exon 10 of the ATXN3 gene but does not assess for CAA interruptions. Our assay involves two amplicon-length assays from both the 3’ and 5’ ends of the repeat region to determine lengths of repeats. … View more
Availability: Help
Tests performed
Entire test performed in-house
Analytical Validity: Help
This test for repeat expansions in ATXN3 has approximately 100% clinical sensitivity for detection of MJD/SCA3 (Paulson and Shakkottai. 2020. PubMed ID: 20301375).
Proficiency testing (PT):
Is proficiency testing performed for this test? Help

Method used for proficiency testing: Help
Software used to interpret novel variations Help
GeneSplicer, Human Splicing Finder, MaxEntScan, Mutation Taster, NNSPLICE, PolyPhen 2, SIFT and Splice Site Finder.

Laboratory's policy on reporting novel variations Help
Sequence variants found in our patients are contributed to ClinVar. Anonymous patient sequence data will also be shared with researchers for preparation of peer-reviewed publications.
Recommended fields not provided:
Regulatory Approval
FDA Review: Help
Category: FDA exercises enforcement discretion
Additional Information

IMPORTANT NOTE: NIH does not independently verify information submitted to GTR; it relies on submitters to provide information that is accurate and not misleading. NIH makes no endorsements of tests or laboratories listed in GTR. GTR is not a substitute for medical advice. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.