| Web: | mayocliniclabs.com |
|---|---|
| Email: | mcl@mayo.edu |
| Telephone: | 800-533-1710 |
| International: | +1 855-379-3115 |
| Values are valid only on day of printing | |
Test Id : SCAP
Spinocerebellar Ataxia Repeat Expansion Panel, Varies
Useful For
Suggests clinical disorders or settings where the test may be helpful
Suggests clinical disorders or settings where the test may be helpful
Molecular confirmation of clinically suspected spinocerebellar ataxia
Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request
Provides information that may help with selection of the correct genetic test or proper submission of the test request
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.
Special Instructions
Library of PDFs including pertinent information and forms related to the test
Library of PDFs including pertinent information and forms related to the test
Method Name
A short description of the method used to perform the test
A short description of the method used to perform the test
Polymerase Chain Reaction (PCR)
NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Yes
Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test
Lists a shorter or abbreviated version of the Published Name for a test
Spinocerebellar Ataxia Panel
Aliases
Lists additional common names for a test, as an aid in searching
Lists additional common names for a test, as an aid in searching
Spinocerebellar ataxia type 1
Spinocerebellar ataxia type 2
Spinocerebellar ataxia type 3
Spinocerebellar ataxia type 6
Spinocerebellar ataxia type 7
SCA1
SCA2
SCA3
SCA6
SCA7
Specimen Type
Describes the specimen type validated for testing
Describes the specimen type validated for testing
Varies
Shipping Instructions
Specimen preferred to arrive within 96 hours of collection.
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
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 specimen in original tube. Do not aliquot.
Special Instructions
Library of PDFs including pertinent information and forms related to the test
Library of PDFs including pertinent information and forms related to the test
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.
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory
0.5 mL
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
Identifies specimen types and conditions that may cause the specimen to be rejected
Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Ambient (preferred) | ||
| Frozen | |||
| Refrigerated | |||
Useful For
Suggests clinical disorders or settings where the test may be helpful
Suggests clinical disorders or settings where the test may be helpful
Molecular confirmation of clinically suspected spinocerebellar ataxia
Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request
Provides information that may help with selection of the correct genetic test or proper submission of the test request
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.
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Spinocerebellar Ataxia Type 1:
Spinocerebellar ataxia type 1 (SCA1) is characterized by progressive ataxia, dysarthria, eventual deterioration of bulbar functions, and ophthalmoplegia. Onset typically occurs in the 3rd to 4th decade of life. Most individuals present with difficulties in gait or slurred speech. SCA1 is caused by an expansion of the cytosine-adenine-guanine (CAG) trinucleotide repeat in the ATXN1 gene. This trinucleotide repeat is polymorphic in the general population, with the number of benign repeats ranging from 6 to 37. The pathogenicity of the repeat is dependent on the presence or absence of cytosine-adenine-thymine (CAT) trinucleotide repeats that interrupt the CAG repeats. Therefore, individuals with 36 to 37 uninterrupted CAG repeats are predisposed to having a child with an expanded allele. In affected individuals, the CAG expansions are greater than 38 uninterrupted CAG repeats or greater than 44 repeats regardless of the presence or absence of CAT repeat interruptions. The presence of CAT repeats in an individual with 36 to 43 repeats is considered normal and not pathogenic. In contrast, 38 repeats without CAT repeats is of uncertain significance. There is a report of an individual with very last onset SCA1 with 38 repeats. Reduced penetrance has been associated with 44 repeats. As with other trinucleotide repeat disorders, large CAG expansions are associated with earlier onset and a more severe clinical course.
SCA2:
Spinocerebellar ataxia type 2 (SCA2) is characterized by slowly progressive ataxia and dysarthria, and slow saccadic eye movements. The mean age of onset is in the 4th decade, but symptoms may appear from childhood to later adulthood. SCA2 is caused by an expansion of the CAG trinucleotide repeat in the ATXN2 gene. This trinucleotide repeat is polymorphic in the general population, with the number of benign repeats less than 32. However, 29 to 31 heterozygous repeats have been associated with an increased exponential risk for amyotrophic lateral sclerosis (ALS). Additionally, there has been a report of an individual homozygous for 31 repeats with late onset cerebellar ataxia. In contrast, 27 repeats have been associated with a protective effect for ALS. In affected individuals the CAG expansion is greater than 34 repeats, with the most common disease-causing alleles have 37 to 39 repeats. Larger CAG expansions are associated with an earlier age of onset but repeat length cannot predict age of onset or disease severity. A CAG expansion of 32 repeats is of unclear clinical significance. Repeats in the 33 to 34 range are associated with reduced penetrance.
SCA3:
Spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease, is characterized by progressive cerebellar ataxia and pyramidal signs. The age of onset is highly variable but most commonly occurs in the 2nd to 5th decade of life. Individuals may present with gait problems, speech difficulties, clumsiness, or visual blurring. SCA3 is caused by an expansion of the CAG trinucleotide repeat in the ATXN3 gene. This trinucleotide repeat is polymorphic in the general population, with the number of benign repeats ranging from 12 to 44. In affected individuals the CAG expansion ranges from 60 to 87 repeats. A loose correlation exists between repeat length and clinical phenotype. Individuals with 45 to 59 CAG repeats are predisposed to having a child with an expanded allele and may or may not have symptoms themselves. There have been reports of reduced penetrant and nonpenetrant alleles with repeats in this range.
SCA6:
Spinocerebellar ataxia type 6 (SCA6) is characterized by adult-onset, slowly progressive cerebellar ataxia, dysarthria, and nystagmus. The mean age of onset is 43 to 52 years. Initial symptoms include unsteadiness, stumbling, and imbalance. SCA6 is caused by an expansion of the CAG trinucleotide repeat in the CACNA1A gene. This trinucleotide repeat is polymorphic in the general population, with the number of benign repeats less than 19. In affected individuals the CAG expansion ranges from 20 to 33 repeats. Larger CAG expansions are associated with an earlier age of onset. A CAG expansion of 19 repeats is of unclear clinical significance. Individuals with 19 CAG repeats are predisposed to having a child with an expanded allele. Additionally, homozygous abnormal expansions have been reported in individuals with younger age of onset and a more severe phenotype.
SCA7:
Spinocerebellar ataxia type 7 (SCA7) is characterized by progressive cerebellar ataxia, including dysarthria and dysphagia, and con-rod and retinal dystrophy. Onset ranges from infancy to the 5th or 6th decade of life. SCA7 is caused by an expansion of the CAG trinucleotide repeat in the ATXN7 gene. This trinucleotide repeat is polymorphic in the general population, with the number of benign repeats less than 19. In affected individuals the CAG expansion is greater than 36 repeats. A CAG expansion of 19 to 27 repeats is of unclear clinical significance. Individuals with 28 to 33 repeats are predisposed to having a child with an expanded allele but are unlikely to have symptoms themselves. Thirty-four to 36 repeats is associated with reduced-penetrance, and when symptoms do occur, they are more likely to be associated with later onset and a milder phenotype.
Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
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.
Interpretation
Provides information to assist in interpretation of the test results
Provides information to assist in interpretation of the test results
An interpretive report will be provided.
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
For predictive testing, it is important to first document the presence of a cytosine-adenine-guanine (CAG)-repeat expansion in an affected family member to confirm that the repeat expansion is the underlying mechanism of disease in the family.
It is strongly recommended that patients undergoing predictive testing receive genetic counseling both prior to testing and after results are available.
Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Errors in the interpretation of results may occur if information given is inaccurate or incomplete.
Due to somatic mosaicism, repeat size identified in the peripheral blood specimen may not reflect the repeat size in untested tissues (eg, central nervous system). In addition, a negative result does not rule out the presence of a variant in the mosaic state that may be present but below the limit of detection of this assay (approximately 10%).
Rare sequence variants immediately downstream of the spinocerebellar ataxia (SCA) repeat regions may interfere with genotype results but are not expected to affect repeat-primed peaks.
Rare undocumented alterations (ie, polymorphisms) in polymerase-chain reaction primer binding regions may lead to false-negative results.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
Recommendations for in-depth reading of a clinical nature
1. Soong BW, Morrison PJ: Spinocerebellar ataxias. Handb Clin Neurol. 2018;155:143-174. doi: 10.1016/B978-0-444-64189-2.00010-X
2. Buijsen RAM, Toonen LJA, Gardiner SL, et al: Genetics, mechanisms, and therapeutic progress in polyglutamine spinocerebellar ataxias. Neurotherapeutics. 2019 Apr;16(2):263-286. doi: 10.1007/s13311-018-00696-y
Special Instructions
Library of PDFs including pertinent information and forms related to the test
Library of PDFs including pertinent information and forms related to the test
Method Description
Describes how the test is performed and provides a method-specific reference
Describes how the test is performed and provides a method-specific reference
A polymerase-chain reaction-based assay is used to amplify across the region of the ATXN1, ATXN2, ATXN3, CACNA1A, or ATXN7 genes containing CAG repeats. Additionally, testing assesses for CAT trinucleotides that interrupt the CAG repeat tract within the ATXN1 gene.(Unpublished Mayo method)
PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information
Indicates whether the report includes an additional document with charts, images or other enriched information
No
Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.
Monday, Wednesday
Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.
5 to 11 days
Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Whole Blood: 2 weeks (if available) Extracted DNA: 3 months
Performing Laboratory Location
Indicates the location of the laboratory that performs the test
Indicates the location of the laboratory that performs the test
Rochester
Fees
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.
- Authorized users can sign in to Test Prices for detailed fee information.
- Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
- Prospective clients should contact their Regional Manager. For assistance, contact Customer Service.
Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.
This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.
CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
CPT codes are provided by the performing laboratory.
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
CPT codes are provided by the performing laboratory.
CPT codes are provided by the performing laboratory.
81178
81179
81180
81181
81184
Test Setup Resources
Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.
Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.
Normal and Abnormal sample reports are provided as references for report appearance.
SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.