Long QT Syndrome (LQTS)

$600.00

Category:

About the Test

Long QT syndrome, Brugada syndrome, and Short QT syndrome are inherited arrhythmias that are often asymptomatic and can lead to sudden cardiac death.

The Long QT Panel examines 34 genes most commonly associated with hereditary Long QT syndrome (LQTS). This test can be an effective way to confirm an arrhythmia disorder and direct medical management and treatment decisions.

Overview

Long QT syndrome, Brugada syndrome, and Short QT syndrome are inherited arrhythmias that are often asymptomatic and can lead to sudden cardiac death.

The Long QT Panel examines 34 genes most commonly associated with hereditary Long QT syndrome (LQTS). This test can be an effective way to confirm an arrhythmia disorder and direct medical management and treatment decisions.

Genes

34 Genes

ABCC9, AKAP9, ANK2, CACNA1C, CACNA2D1, CACNB2, CALM1, CALM2, CALM3, CAV3, GPD1L, HCN4, KCND3, KCNE1, KCNE2, KCNE3, KCNE5, KCNH2, KCNJ2, KCNJ5, KCNJ8, KCNQ1, PKP2, RANGRF, SCN10A, SCN1B, SCN2B, SCN3B, SCN4B, SCN5A, SLMAP, SNTA1, TRDN, TRPM4

Disorders
Gene Function
When To Order

Patients with a personal and/or family history suggestive of LQTS or Brugada syndrome. Long QT syndrome is defined by an increased QT interval on an electrocardiogram (ECG). Brugada syndrome has abnormal ECG findings as well, including broad P wave, J point elevation, coved ST elevation, and inverted T wave. Red flags for LQTS or Brugada syndrome can include, but are not limited to, episodes of heart palpitations, dizziness, fainting, shortness of breath, seizures, cardiac arrest, and sudden cardiac death. Some individuals found to have a LQTS or Brugada syndrome gene mutation may never develop symptoms.

Benefit To My Patient

Patients identified with LQTS or Brugada syndrome can benefit from increased surveillance and preventative steps to better manage their risks. Medical intervention can include beta blockers, implantable devices, and lifestyle changes. Also, your patient’s family members can be tested to help define their risk. If a pathogenic variant is identified in your patient, close relatives (children, siblings, parents) could have as high as a 50% risk to also be at increased risk. In some cases, screening should begin in childhood.

Clinical Utility
Lab Method & Assay
  • Next-Generation  Sequencing
  • Deletion/Duplication Analysis
  • Pathogenic and Likely Pathogenic Variants Confirmed With Sanger Sequencing
  • Coverage: 96% at 20X
Test Limitations

All sequencing technologies have limitations. This analysis is performed by Next Generation Sequencing (NGS) and is designed to examine coding regions and splicing junctions. Although next generation sequencing technologies and our bioinformatics analysis significantly reduce the contribution of pseudogene sequences or other highly-homologous sequences, these may still occasionally interfere with the technical ability of the assay to identify pathogenic variant alleles in both sequencing and deletion/duplication analyses. Sanger sequencing is used to confirm variants with low quality scores and to meet coverage standards. If ordered, deletion/duplication analysis can identify alterations of genomic regions which include one whole gene (buccal swab specimens and whole blood specimens) and are two or more contiguous exons in size (whole blood specimens only); single exon deletions or duplications may occasionally be identified, but are not routinely detected by this test. Identified putative deletions or duplications are confirmed by an orthogonal method (qPCR or MLPA). This assay will not detect certain types of genomic alterations which may cause disease such as, but not limited to, translocations or inversions, repeat expansions (eg. trinucleotides or hexanucleotides), alterations in most regulatory regions (promoter regions) or deep intronic regions (greater than 20bp from an exon). This assay is not designed or validated for the detection of somatic mosaicism or somatic mutations.

Test Code
Specimen Requirements

Buccal Swab

Turn Around Time

3 – 5 weeks

CPT Codes

81404, 81406, 81407, 81479×1

NOTE: The CPT codes listed on the website are in accordance with Current Procedural Terminology, a publication of the American Medical Association. CPT codes are provided here for the convenience of our clients. Clients who bill for services should make the final decision on which codes to use.

References
  1. Beckmann, B.M., Pfeufer, A., & Kääb, S. Inherited cardiac arrhythmias: diagnosis, treatment, and prevention. Dtsch Arztebl Int. 2011 Sep;108(37):623-33 (2011)
  2. Brugada, R., Campuzano O., Sarquella-Brugada, G., et al. Brugada Syndrome. 2005 Mar 31 [Updated 2016 Nov 17]. In: Pagon RA, Adam MP, Ardinger HH, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle (1993-2017)
  3. Alders, M., Christiaans, I. Long QT Syndrome. 2003 Feb 20 [Updated 2015 Jun 18]. In: Pagon RA, Adam MP, Ardinger HH, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle (1993-2017)
  4. Kim, J.B. Channelopathies. Korean J Pediatr. 2014 Jan;57(1):1-18. doi: 10.3345/kjp.2014.57.1.1. (2014)