Long QT Syndrome via the KCNH2 Gene

Summary and Pricing

Test Method

Sequencing and CNV Detection via NextGen Sequencing using PG-Select Capture Probes
Test Code Test Copy GenesTest CPT Code Gene CPT Codes Copy CPT Codes Base Price
4875 KCNH2 81406 81406,81479 $640 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
4875KCNH281406 81406(x1), 81479(x1) $640 Order Options and Pricing

Pricing Comments

This test is also offered via our exome backbone with CNV detection (click here). The exome-based test may be higher priced, but permits reflex to the entire exome or to any other set of clinically relevant genes.

An additional 25% charge will be applied to STAT orders. STAT orders are prioritized throughout the testing process.

Turnaround Time

18 days on average for standard orders or 13 days on average for STAT orders.

Please note: Once the testing process begins, an Estimated Report Date (ERD) range will be displayed in the portal. This is the most accurate prediction of when your report will be complete and may differ from the average TAT published on our website. About 85% of our tests will be reported within or before the ERD range. We will notify you of significant delays or holds which will impact the ERD. Learn more about turnaround times here.

Targeted Testing

For ordering sequencing of targeted known variants, go to our Targeted Variants page.

EMAIL CONTACTS

Genetic Counselors

Geneticist

  • Chun-An Chen, PhD

Clinical Features and Genetics

Clinical Features

Long QT syndrome (LQTS) is a heritable channelopathy characterized by an exceedingly prolonged cardiac repolarization that may trigger ventricular arrhythmias (torsade de pointes), recurrent syncopes, seizure, or sudden cardiac death (SCD) (Cerrone et al. 2012). LQTS can manifest with syncope and cardiac arrest that is commonly triggered by adrenergic stress, often precipitated by emotion or exercise. Roughly 10% to 15% of patients experience symptoms at rest or during the night (Schwartz et al. 2001). The mean age of onset of symptoms is 12 years, and earlier onset usually is associated with a more severe form of the disease (Priori et al 2004). Inherited LQTS occurs due to mutations in multiple genes such as KCNQ1 (LQT1), KCNH2 (LQT2), SCN5A (LQT3), KCNE1 (LQT5) and KCNE2 (LQT6), but it can also be acquired (acquired LQTS), usually as a result of pharmacological therapy. A small percentage of cases of acquired LQTS occur in people who have an underlying variation in the KCNH2 gene.

Genetics

LQT2 accounts for about 45% of all long QT syndrome cases and occurs due to heterozygous mutations in the KCNH2 (HERG) gene (Splawski et al. 2000), suggesting an autosomal dominant mode of inheritance. Female predominance has often been observed and has sometimes been attributed to an increased susceptibility to cardiac arrhythmias in women (Imboden et al. 2006). KCNH2 codes for the voltage-gated potassium channel protein that is highly expressed in the heart muscle and helps transport positively charged potassium ions out of cells. In the heart, the channels are involved in recharging the cardiac muscle after each heartbeat to maintain a regular rhythm. The KCNH2 protein is also produced in nerve cells and certain immune cells (microglia) in the central nervous system. Causative mutations in KCNH2 include missense, nonsense and splicing variants as well as small deletions and insertions (Splawski et al. 2000). Causative mutations in the KCNH2 gene are also associated with acquired long QT syndrome.

Clinical Sensitivity - Sequencing with CNV PG-Select

Approximately 45% of all long QT syndrome cases occur due to heterozygous mutations in the KCNH2 gene (Splawski et al. 2000).

Gross deletions and duplications in the KCNH2 gene have been reported in patients with Long QT syndrome.

Testing Strategy

This test provides full coverage of all coding exons of the KCNH2 gene, plus ~10 bases of flanking noncoding DNA. We define full coverage as >20X NGS reads or Sanger sequencing.

Indications for Test

All patients with symptoms suggestive of Long QT syndrome are candidates for this test.

Gene

Official Gene Symbol OMIM ID
KCNH2 152427
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Diseases

Name Inheritance OMIM ID
Long QT Syndrome 2 AD 613688
Short QT Syndrome 1 AD 609620

Related Tests

Name
Andersen-Tawil Syndrome/Long QT Syndrome via the KCNJ2 Gene
Catecholaminergic Polymorphic Ventricular Tachycardia and Long QT Syndrome via the CALM1 Gene
Comprehensive Cardiac Arrhythmia Panel
Comprehensive Cardiology Panel
Familial Atrial Fibrillation Syndrome Panel
Fetal Concerns Panel
Long QT Syndrome and Jervell and Lange-Nielsen Syndrome via the KCNE1 Gene
Long QT Syndrome via the KCNE2 Gene
Long QT Syndrome via the KCNJ5 Gene
Long QT Syndrome via the SCN4B Gene
Long QT Syndrome via the SNTA1 Gene
Short QT Syndrome Panel
Sudden Cardiac Arrest Panel

Citations

  • Cerrone M. et al. 2012. Circulation. Cardiovascular genetics. 5: 581-90. PubMed ID: 23074337
  • Imboden M, Swan H, Denjoy I, Van Langen IM, Latinen-Forsblom PJ, Napolitano C, Fressart V, Breithardt G, Berthet M, Priori S, Hainque B, Wilde AA, Schulze-Bahr E, Feingold J, Guicheney P. 2006. Female predominance and transmission distortion in the long-QT syndrome. New England Journal of Medicine 355: 2744–2751. PubMed ID: 17192539
  • Priori et al. 2004. PubMed ID: 15367556
  • Schwartz et al. 2001. PubMed ID: 11136691
  • Splawski I. et al. 2000. Circulation. 102: 1178-85. PubMed ID: 10973849

Ordering/Specimens

Ordering Options

We offer several options when ordering sequencing tests. For more information on these options, see our Ordering Instructions page. To view available options, click on the Order Options button within the test description.

myPrevent - Online Ordering

  • The test can be added to your online orders in the Summary and Pricing section.
  • Once the test has been added log in to myPrevent to fill out an online requisition form.
  • PGnome sequencing panels can be ordered via the myPrevent portal only at this time.

Requisition Form

  • A completed requisition form must accompany all specimens.
  • Billing information along with specimen and shipping instructions are within the requisition form.
  • All testing must be ordered by a qualified healthcare provider.

For Requisition Forms, visit our Forms page


Specimen Types

Specimen Requirements and Shipping Details

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ORDER OPTIONS

View Ordering Instructions

1) Select Test Method (Backbone)


1) Select Test Type


2) Select Additional Test Options

STAT and Prenatal Test Options are not available with Patient Plus.

No Additional Test Options are available for this test.

Note: acceptable specimen types are whole blood and DNA from whole blood only.
Total Price: $
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