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HelpTest Code CSTB CSTB Gene, Repeat Expansion Analysis, Varies
Ordering Guidance
This test only detects dodecamer repeat expansions. If testing for both dodecamer repeat expansions and other CSTB variants is requested, order a custom gene panel for the CSTB gene. For more information see CGPH / Custom Gene Panel, Hereditary, Next-Generation Sequencing, Varies.
Shipping Instructions
Specimen Required
Patient Preparation: A previous hematopoietic stem cell transplant from an allogenic donor will interfere with testing. For information about testing patients who have received a hematopoietic stem cell 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: Green top (sodium heparin)
Specimen Volume: 3 mL
Collection Instructions:
1. Invert several times to mix blood.
2. Send whole blood specimen in original tube. Do not aliquot.
3. Whole blood collected postnatal from an umbilical cord is also acceptable. See Additional Information.
Specimen Stability Information: Ambient 4 days (preferred)/Refrigerated 4 days/Frozen 4 days
Additional Information:
1. Specimens are preferred to be received within 4 days of collection. Extraction will be attempted for specimens received after 4 days, and DNA yield will be evaluated to determine if testing may proceed.
2. To ensure minimum volume and concentration of DNA are met, the requested volume must be submitted. Testing may be canceled if DNA requirements are inadequate.
3. For postnatal umbilical cord whole blood specimens, maternal cell contamination studies are recommended to ensure test results reflect that of the patient tested. A maternal blood specimen is required to complete maternal cell contamination studies. Order MATCC / Maternal Cell Contamination, Molecular Analysis, Varies on both the cord blood and maternal blood specimens under separate order numbers.
Specimen Type: Extracted DNA
Container/Tube:
Preferred: Screw Cap Micro Tube, 2 mL with skirted conical base
Acceptable: Matrix tube, 1 mL
Collection Instructions:
1. The preferred volume is at least 100 mcL at a concentration of 75 ng/mcL.
2. Include concentration and volume on tube.
Specimen Stability Information: Frozen (preferred) 1 year/Ambient/Refrigerated
Additional Information: DNA must be extracted in a CLIA-certified laboratory or equivalent and must be extracted from a specimen type listed as acceptable for this test (including applicable anticoagulants). Our laboratory has experience with Chemagic, Puregene, Autopure, MagnaPure, and EZ1 extraction platforms and cannot guarantee that all extraction methods are compatible with this test. If testing fails, one repeat will be attempted, and if unsuccessful, the test will be reported as failed and a charge will be applied. If applicable, specific gene regions that were unable to be interrogated due to DNA quality will be noted in the report.
Forms
1. New York Clients-Informed consent is required. Please 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 CSTB-related progressive myoclonic epilepsy
Identifying full penetrance dodecamer repeat expansions within CSTB known to cause CSTB-related progressive myoclonic epilepsy, allowing for predictive testing of at-risk family members
Impacting patient treatment and management through the identification of a specific underlying etiology for epilepsy (eg, directing appropriate use of anti-epileptic drugs and other treatment modalities)
Special Instructions
Method Name
Polymerase Chain Reaction (PCR)
Reporting Name
CSTB, Repeat Expansion AnalysisSpecimen Type
VariesSpecimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Varies | Varies | |
Reject Due To
All specimens will be evaluated by Mayo Clinic Laboratories for test suitability.Reference Values
Normal: <5 dodecamer repeats
Repeat Size of Uncertain Significance: 5-29 dodecamer repeats
Full Penetrance Expansion: >29 dodecamer repeats
An interpretive report will be provided.
Day(s) Performed
Varies
Report Available
14 to 28 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
81188
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| CSTB | CSTB, Repeat Expansion Analysis | 41110-8 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 616516 | Result Summary | 50397-9 |
| 616517 | Result | 82939-0 |
| 616518 | Interpretation | 69047-9 |
| 616519 | Reason for Referral | 42349-1 |
| 616520 | Specimen | 31208-2 |
| 616521 | Method | 85069-3 |
| 616522 | Source | 31208-2 |
| 616523 | Released By | 18771-6 |
Testing Algorithm
For cord blood specimens that have an accompanying maternal blood specimen, maternal cell contamination studies will be performed at an additional charge.
For more information see Epilepsy: Unexplained Refractory and/or Familial Testing Algorithm
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| MATCC | Maternal Cell Contamination, B | Yes | No |