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Early Infantile Epileptic Encephalopathy 24 via the HCN1 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
8199 HCN1 81479 81479,81479 $640 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
8199HCN181479 81479,81479 $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

  • Eric Bend, PhD

Clinical Features and Genetics

Clinical Features

Early infantile epileptic encephalopathy 24 is known as Dravet-like syndrome. Patients with a pathogenic variant in HCN1 have clinical symptoms resembling those of Dravet syndrome with progression toward atypical absences, intellectual disability and autistic traits (Nava et al. 2014). Patients have similar clinical features of seizures beginning at ages of 4 to 13 months and a combination of febrile and afebrile seizures, including hemiclonic and generalized seizures. These manifestations are initially suggestive of Dravet syndrome, but show different progression over time. Atypical absences, with or without myoclonic jerks, and focal seizures become predominant in older patients. All affected patients have mild to severe intellectual disability and major behavioral disturbances, including autistic traits (Nava et al. 2014).

Genetics

Early infantile epileptic encephalopathy 24 is inherited in an autosomal dominant manner and is caused by pathogenic variants in HCN1 which encodes Hyperpolarization-activated cyclic nucleotide-gated potassium channel 1. HCN channels are activated by membrane hyperpolarization at voltages close to resting membrane potentials and carry the hyperpolarization-activated current, dubbed If (funny current) in heart and Ih in neurons (DiFrancesco et al. 2015). HCN1 is one of four genes (HCN1-4) with different biophysical properties expressed in the heart and brain.

The reported HCN1 pathogenic variants are missense variants (Human Gene Mutation Database). Most of the pathogenic missense variants have gain-of-function with possible dominant-negative effect (DiFrancesco et al. 2015). Some of the pathogenic variants occur de novo (Nava et al. 2014). Copy number variants (CNVs) encompassing HCN1 exons have been reported in healthy and intellectually disabled individuals at similarly low frequencies (Nava et al. 2014; Poduri et al. 2014). To date, no pathogenic large deletions/duplications have been reported in HCN1 (HGMD).

Clinical Sensitivity - Sequencing with CNV PG-Select

Pathogenic variants in HCN1 caused early infantile epileptic encephalopathy in roughly 2.5% of the cases in a screening cohort (Nava et al. 2014).

Testing Strategy

This test provides full coverage of all coding exons of the HCN1 gene, plus ~10 bases of flanking noncoding DNA. We define full coverage as >20X NGS reads or Sanger sequencing.

Indications for Test

Sequencing is recommended for cases who are suspected to have early infantile epileptic encephalopathy 24.

Gene

Official Gene Symbol OMIM ID
HCN1 602780
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Disease

Name Inheritance OMIM ID
Epileptic Encephalopathy, Early Infantile, 24 AD 615871

Citations

  • DiFrancesco J.C., DiFrancesco D. 2015. Frontiers in Cellular Neuroscience. 6: 174. PubMed ID: 25805968
  • Human Gene Mutation Database (Bio-base).
  • Nava C. et al. 2014. Nature Genetics. 46: 640-5. PubMed ID: 24747641
  • Poduri A. 2014. Epilepsy Currents. 14: 348-9. PubMed ID: 25678871

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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