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HelpTest Code SCARA Spinocerebellar Ataxia Type 1, 2, 3, 6, or 7, Repeat Expansion Analysis, Varies
Ordering Guidance
This test is not a gene panel for all types of spinocerebellar ataxia (SCA). If individual findings are not specific for one type of SCA, panel analysis is available and includes testing for SCA1, 2, 3, 6, and 7; order SCAP / Spinocerebellar Ataxia Repeat Expansion Panel, Varies.
This test and SCAP should not be ordered concurrently.
Shipping Instructions
Specimen preferred to arrive within 96 hours of collection.
Necessary Information
The type of spinocerebellar ataxia (SCA) to be assessed (SCA1, 2, 3, 6, or 7) is required. This information must be provided for testing to be performed.
Specimen Required
Patient Preparation: A previous bone marrow transplant from an allogenic donor will interfere with testing. For instructions for testing patients who have received a bone marrow transplant, call 800-533-1710.
Submit only 1 of the following specimens:
Specimen Type: Whole blood
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.
Specimen Stability Information: Ambient (preferred) 4 days/Refrigerated
Prenatal Specimens
Due to its complexity, consultation with the laboratory is required for all prenatal testing; call 800-533-1710 to speak to a genetic counselor.
Specimen Type: Amniotic fluid
Container/Tube: Amniotic fluid container
Specimen Volume: 20 mL
Specimen Stability Information: Refrigerated (preferred)/Ambient
Additional information:
1. A separate culture charge will be assessed under CULAF / Culture for Genetic Testing, Amniotic Fluid.
2. All prenatal specimens must be accompanied by a maternal blood specimen; order MATCC / Maternal Cell Contamination, Molecular Analysis, Varies on the maternal specimen.
Specimen Type: Chorionic villi
Container/Tube: 15-mL tube containing 15 mL of transport media
Specimen Volume: 20 mg
Specimen Stability Information: Refrigerated
Additional Information:
1. A separate culture charge will be assessed under CULFB / Fibroblast Culture for Biochemical or Molecular Testing.
2. All prenatal specimens must be accompanied by a maternal blood specimen; order MATCC / Maternal Cell Contamination, Molecular Analysis, Varies on the maternal specimen.
Acceptable:
Specimen Type: Confluent cultured cells
Container/Tube: T-25 flask
Specimen Volume: 2 Full flasks
Collection Instructions: Submit confluent cultured cells from another laboratory.
Specimen Stability Information: Ambient (preferred)/Refrigerated
Additional Information: All prenatal specimens must be accompanied by a maternal blood specimen; order MATCC / Maternal Cell Contamination, Molecular Analysis, Varies on the maternal specimen.
Genetics Test Information
This test is for the assessment of one type of the specified spinocerebellar ataxias (SCA), including types 1, 2, 3, 6, or 7. It assesses for CAG (cytosine-adenine-guanine) repeat expansions within the ATXN1, ATXN2, ATXN3, CACNA1A, or ATXN7 genes, associated with SCA1, SCA2, SCA3, SCA6, and SCA7. Additionally, testing for ATXN1 assesses for CAT (cytosine-adenine-thymine) trinucleotides that interrupt the CAG repeat tract.
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| CULFB | Fibroblast Culture for Genetic Test | Yes | No |
| CULAF | Amniotic Fluid Culture/Genetic Test | Yes | No |
| MATCC | Maternal Cell Contamination, B | Yes | No |
| G204 | ATXN1 (SCA 1) Gene Analysis | No, (Bill Only) | No |
| G205 | ATXN2 (SCA 2) Gene Analysis | No, (Bill Only) | No |
| G206 | ATXN3 (SCA 3) Gene Analysis | No, (Bill Only) | No |
| G207 | ATXN7 (SCA 7) Gene Analysis | No, (Bill Only) | No |
| G208 | CACNA1A (SCA 6) Gene Analysis | No, (Bill Only) | No |
Specimen Type
VariesSpecimen Minimum Volume
Amniotic fluid: 10 mL
Blood: 0.5 mL
Chorionic villi: 5 mg
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Varies | ||
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.
Day(s) Performed
Monday, Wednesday
Report Available
21 to 28 daysSpecimen Retention Time
Whole blood: 2 weeks (if available); Extracted DNA: 3 months; Amniotic fluid, chorionic villi, cultured chorionic villi: 1 monthPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
88233-Fibroblast Culture (if appropriate)
88235-Amniotic Fluid Culture (if appropriate)
88240-Cryopreservation (if appropriate)
81265-Maternal Cell Contamination (if appropriate)
81178 (if appropriate)
81179 (if appropriate)
81180 (if appropriate)
81181 (if appropriate)
81184 (if appropriate)