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Order Code SCAP Spinocerebellar Ataxia Repeat Expansion Panel, Varies


Shipping Instructions


Specimen preferred to arrive within 96 hours of collection.



Specimen Required


Specimen Type: Whole blood

Patient Preparation: A previous bone marrow transplant from an allogenic donor will interfere with testing. Call 800-533-1710 for instructions for testing patients who have received a bone marrow transplant.

Container/Tube:

Preferred: Lavender top (EDTA) or yellow top (ACD)

Acceptable: Any anticoagulant

Specimen Volume: 3 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send whole blood specimen in original tube. Do not aliquot.


Forms

1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. Molecular Genetics: Neurology Patient Information

3. If not ordering electronically, complete, print, and send a Neurology Specialty Testing Client Test Request (T732) with the specimen.

Useful For

Molecular confirmation of clinically suspected spinocerebellar ataxia when a specific subtype isn’t suspected

Genetics Test Information

This test assesses for CAG repeat expansions within the ATXN1, ATXN2, ATXN3, CACNA1A, and ATXN7 genes, associated with spinocerebellar ataxia (SCA) type 1, SCA2, SCA3, SCA6, and SCA7. Additionally, testing for ATXN1 assesses for CAT trinucleotides that interrupt the CAG repeat tract.

Method Name

Polymerase Chain Reaction (PCR)

Reporting Name

Spinocerebellar Ataxia Panel

Specimen Type

Varies

Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Ambient (preferred)
  Frozen 
  Refrigerated 

Reject Due To

  Specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Reference Values

SPINOCEREBELLAR ATAXIA TYPE 1

Normal alleles: <36 CAG repeats

Normal alleles with CAT interruptions: 36-43 repeats

Intermediate alleles without CAT interruptions: 36-37 repeats

Uncertain significance: 38 repeats

Expanded alleles without CAT interruptions: >38 CAG repeats

Expanded alleles with CAT interruptions: >43 CAG repeats

 

SPINOCEREBELLAR ATAXIA TYPE 2

Normal alleles: <32 repeats

Uncertain significance: 31 homozygous and 32 repeats

Reduced penetrance: 33-34 repeats

Expanded alleles: >34 repeats

 

SPINOCEREBELLAR ATAXIA TYPE 3

Normal alleles: <45 repeats

Intermediate alleles: 45-59 repeats

Expanded alleles: >59 repeats

 

SPINOCEREBELLAR ATAXIA TYPE 6

Normal alleles: <19 repeats

Intermediate alleles: 19 heterozygous repeats

Uncertain significance: 19 homozygous repeats

Expanded alleles: >19 repeats

 

SPINOCEREBELLAR ATAXIA TYPE 7

Normal alleles: <19 repeats

Uncertain significance: 19-27 repeats

Intermediate alleles: 28-33 repeats

Reduced penetrance: 34-36 repeats

Expanded alleles: >36 repeats

 

An interpretive report will be provided.

Method Description

A polymerase-chain reaction-based assay is used to amplify across the region of the ATXN1, ATXN2, ATXN3, CACNA1A, or ATXN7 genes containing CAG (cytosine-adenine-guanine) repeats. Additionally, testing assesses for CAT (cytosine-adenine-thymine) trinucleotides that interrupt the CAG repeat tract within the ATXN1 gene.(Unpublished Mayo method)

Day(s) Performed

Monday, Wednesday

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

81178

81179

81180

81181

81184

81479 (if appropriate for government payers)