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HelpTest Code SQTSG Short QT Syndrome Gene Panel, Varies
Ordering Guidance
This test is intended for genetic screening for and diagnosis of short QT syndrome.
For comprehensive inherited cardiac arrhythmia genetic testing, order CARGG / Comprehensive Arrhythmia Gene Panel, Varies.
Customization of this panel and single gene analysis for any gene present on this panel are available. For more information see CGPH / Custom Gene Panel, Hereditary, Next-Generation Sequencing, Varies.
Targeted testing for familial variants (also called site-specific or known mutations testing) is available for the genes on this panel. See FMTT / Familial Variant, Targeted Testing, Varies.
Shipping Instructions
Specimen preferred to arrive within 96 hours of collection.
Necessary Information
Prior Authorization is available, but not required, for this test. If proceeding with the prior authorization process, submit the required form with the specimen.
Specimen Required
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.
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)/Refrigerated
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. Hereditary Cardiomyopathies and Arrhythmias Patient Information (T725)
3. Short QT Syndrome Gene Panel (SQTSG) Prior Authorization Ordering Instructions
4. If not ordering electronically, complete, print, and send a Cardiovascular Test Request (T724) with the specimen.
Secondary ID
617463Useful For
Providing a genetic evaluation for patients with a personal or family history suggestive of short QT syndrome
Establishing a diagnosis of short QT syndrome
Special Instructions
Method Name
Sequence Capture and Targeted Next-Generation Sequencing followed by Polymerase Chain Reaction (PCR) and Sanger Sequencing
Reporting Name
Short QT Syndrome Gene PanelSpecimen Type
VariesSpecimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Varies | Varies | ||
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Clinical Information
Short QT syndrome (SQTS) is a genetic cardiac arrhythmia condition characterized by a shortened QT interval and T-wave abnormalities on electrocardiogram (ECG).(1) SQTS may result in or present with recurrent syncope, ventricular arrhythmia, sudden cardiac arrest, and sudden cardiac death.(1)
The prevalence of SQTS is unknown, but the condition is thought to be rare.(2) The overall diagnostic yield of genetic testing for SQTS is estimated to be 5% to 20%.(2,3) While disease-causing variants in several genes have been reported in association with SQTS, the strongest evidence of association is currently limited to gain-of- function variants in the cardiac ion change genes KCNH2, KCNJ2, and KCNQ1,(4) and loss-of-function variants in the SLC4A3 gene.(5) Based on current knowledge, SQTS follows an autosomal dominant pattern of inheritance.
Genetic testing in SQTS is recommended to confirm the clinical diagnosis, assist with risk stratification, guide management, and identify at-risk family members. Even individuals with a normal QT interval may still be at risk for a cardiac event and sudden cardiac death; thus, ECG analysis alone is insufficient to rule out the diagnosis, and genetic testing is necessary to confirm the presence or absence of disease in at-risk family members.(1-5)
Reference Values
An interpretive report will be provided.
Interpretation
All detected variants are evaluated according to American College of Medical Genetics and Genomics recommendations.(6) Variants are classified based on known, predicted, or possible pathogenicity and reported with interpretive comments detailing their potential or known significance.
Method Description
Next-generation sequencing (NGS) and/or Sanger sequencing are performed to test for the presence of variants in coding regions and intron/exon boundaries of the genes analyzed, as well as some other regions that have known disease-causing variants. The human genome reference GRCh37/hg19 build was used for sequence read alignment. At least 99% of the bases are covered at a read depth over 30X. Sensitivity is estimated at above 99% for single nucleotide variants, above 94% for deletions-insertions (delins) less than 40 base pairs (bp), above 95% for deletions up to 75 bp and insertions up to 47 bp. NGS and/or a polymerase chain reaction-based quantitative method is performed to test for the presence of deletions and duplications in the genes analyzed.
There may be regions of genes that cannot be effectively evaluated by sequencing or deletion and duplication analysis as a result of technical limitations of the assay, including regions of homology, high guanine-cytosine (GC) content, and repetitive sequences. See Targeted Genes and Methodology Details for Short QT Syndrome Gene Panel for details regarding the targeted genes analyzed for each test and specific gene regions not routinely covered.(Unpublished Mayo method)
Confirmation of select reportable variants may be performed by alternate methodologies based on internal laboratory criteria.
Genes analyzed: KCNH2, KCNJ2, KCNQ1, and SLC4A3
Day(s) Performed
Varies
Performing 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
81403
81406 x 2
81479
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| SQTSG | Short QT Syndrome Gene Panel | 51966-0 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 617464 | Test Description | 62364-5 |
| 617465 | Specimen | 31208-2 |
| 617466 | Source | 31208-2 |
| 617467 | Result Summary | 50397-9 |
| 617468 | Result | 82939-0 |
| 617469 | Interpretation | 69047-9 |
| 617470 | Additional Results | 82939-0 |
| 617471 | Resources | 99622-3 |
| 617472 | Additional Information | 48767-8 |
| 617473 | Method | 85069-3 |
| 617474 | Genes Analyzed | 48018-6 |
| 617475 | Disclaimer | 62364-5 |
| 617476 | Released By | 18771-6 |
Prior Authorization
Insurance preauthorization is available for this testing; forms are available.
Patient financial assistance may be available to those who qualify. Patients who receive a bill from Mayo Clinic Laboratories will receive information on eligibility and how to apply.