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Generalized Epilepsy with Febrile Seizures Plus and Dravet syndrome via the SCN1B 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
10671 SCN1B 81404 81404,81479 $640 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
10671SCN1B81404 81404,81479 $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

Generalized epilepsy with febrile seizures plus (GEFS+; OMIM:604233) is a familial epilepsy syndrome characterized by  febrile seizures. GEFS+ patients usually present with fever induced seizures between the ages of 6 months and 6 years. 'Plus' refers to the persistence of seizures into adolescence when patients may also experience myoclonic, absence or focal seizures. Patients with GEFS+ usually have at least two family members with GEFS+ spectrum phenotypes and seizure-type heterogeneity is typical among family members (Scheffer et al. Brain Dev 31(5):394-400, 2009).

Dravet syndrome (DS; OMIM: 607208) is one of a group of early infantile epileptic encephalopathies (EIEE). DS is characterized by the onset of seizures within the first year of life in children with previously normal psychomotor development. Early seizures can be clonic or clonic-tonic and are usually brought on by fever. DS is characterized by the presence of multiple seizure types within a patient, including: myoclonic jerks, absence seizures, focal seizures, photosensitive seizures and prolonged seizures resulting in status epilepticus (Akiyama et al. Acta Med. Okayama 66(5):369-376, 2012). Seizures observed in DS are resistant to treatment with anti-epileptic drugs. DS patients suffer severe cognitive and motor impairments that persist throughout their lives.

Genetics

GEFS+ is inherited in an autosomal dominant manner with incomplete penetrance. Mutations in SCN1B have been identified in a small percent of GEFS+ families and show ~63% penetrance (Audenaert et al. Neurology 61(6):854-856, 2003). GEFS+ cases can also be sporadic with no family history.

Recessive mutations in SCN1B have also been reported in rare cases of Dravet syndrome (Patino et al. J Neurosci 29(34):10764-10778, 2009; Ogiwara et al. Epilepsia. 53(12):e200-e203, 2012).

SCN1B encodes a beta subunit of the voltage-gated sodium channel. SCN1B has been shown to modulate the excitability of sodium channels, mediate cell-cell adhesions and direct neurite outgrowth- all of which may contribute to the epilepsy phenotypes associated with SCN1B mutations (Patino et al., 2009).

Clinical Sensitivity - Sequencing with CNV PG-Select

SCN1B mutations are found in 1-2% of patients with idiopathic childhood epilepsies and ~4% of cases where febrile seizures are a key clinical feature (Orrico et al. Clin Genet 75(6):579-581; Scheffer et al. Brain 130(Pt 1):100-109, 2007).

Thus far, no gross deletions or duplications have been reported in SCN1B (Human Gene Mutation Database).

Testing Strategy

This test provides full coverage of all coding exons of the SCN1B gene, plus ~10 bases of flanking noncoding DNA. We define full coverage as >20X NGS reads or Sanger sequencing.

Indications for Test

Candidates for SCN1B sequencing include patients with symptoms of GEFS+ with at least two family members affected with GEFS+-spectrum disorders. SCN1B should also be considered for patients who display clinical features of Dravet syndrome, but for which no SCN1A mutation was identified. Normal development prior to seizure onset and seizures that are sensitive to elevated body temperature are two symptoms which are strong indicators for SCN1A and SCN1B testing  (Fountain-Capal et al. Pediatr Neurol 45(5):319-323, 2011).

Gene

Official Gene Symbol OMIM ID
SCN1B 600235
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Citations

  • Akiyama M. et al. 2012. Acta Medica Okayama. 66: 369-76. PubMed ID: 23093055
  • Audenaert D et al. 2003. Neurology. 61: 854-6. PubMed ID: 14504340
  • Fountain-Capal JK, Holland KD, Gilbert DL, Hallinan BE. 2011. When Should Clinicians Order Genetic Testing for Dravet Syndrome? Pediatric Neurology 45: 319–323. PubMed ID: 22000312
  • Human Gene Mutation Database (Bio-base).
  • Ogiwara I. et al. 2012. Epilepsia 53: e200–e203. PubMed ID: 23148524
  • Orrico A. et al. 2009. Clinical Genetics. 75: 579-81. PubMed ID: 19522081
  • Patino GA et al. 2009. The Journal of Neuroscience : the Official Journal of the Society For Neuroscience. 29: 10764-78. PubMed ID: 19710327
  • Scheffer IE et al. 2007. Brain : a Journal of Neurology. 130: 100-9. PubMed ID: 17020904
  • Scheffer IE. et al. 2009. Brain and Development 31: 394–400. PubMed ID: 19203856

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.
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