Generalized Epilepsy With Febrile Seizures Plus via the GABRG2 Gene
Summary and Pricing 
Test Method
Sequencing and CNV Detection via NextGen Sequencing using PG-Select Capture Probes| Test Code | Test Copy Genes | Test CPT Code | Gene CPT Codes Copy CPT Code | Base Price | |
|---|---|---|---|---|---|
| 4159 | GABRG2 | 81405 | 81405,81479 | $990 | Order Options and Pricing |
Pricing Comments
Testing run on PG-select capture probes includes CNV analysis for the gene(s) on the panel but does not permit the optional add on of exome-wide CNV analysis. Any of the NGS platforms allow reflex to other clinically relevant genes, up to whole exome or whole genome sequencing depending upon the base platform selected for the initial test.
An additional 25% charge will be applied to STAT orders. STAT orders are prioritized throughout the testing process.
This test is also offered via a custom panel (click here) on our exome or genome backbone which permits the optional add on of exome-wide CNV or genome-wide SV analysis.
Turnaround Time
3 weeks on average for standard orders or 2 weeks 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.
Clinical Features and Genetics
Clinical Features
Idiopathic generalized epilepsy (IGE) is a clinically and genetically heterogeneous group of epilepsy disorders. IGE has a strong genetic basis, is not usually associated with cognitive defects and presents during childhood or adolescence. Sub-types of IGE include: juvenile myoclonic epilepsy (JME), childhood absence epilepsy (CAE), and generalized epilepsy with febrile seizures plus (GEFS+).
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 (Audenaert et al. 2006).
Genetics
GEFS+ is inherited in an autosomal dominant manner and can be caused by mutations in the GABRG2 gene. Both missense and nonsense mutations in GABRG2 have been reported in cases of GEFS+. The penetrance of GABRG2 mutations is incomplete (Lachance-Touchette et al. 2011).
The GABRG2 gene encodes a subunit of the neuronally expressed GABAA receptor. GABA is an inhibitory neurotransmitter responsible for modulating signaling in the brain. Mutations in GABAA receptor subunits decrease the receptor's response to GABA, thus reducing GABA-signaling. It is proposed that this loss of inhibition in neurons results in increased synaptic excitation and epilepsy (Lachance-Touchette et al. 2011). It has been demonstrated that some mutations in GABRG2 are especially sensitive to elevated temperature, hence their association with febrile seizures (Kang et al. 2006).
Clinical Sensitivity - Sequencing with CNV PG-Select
GABRG2 mutations account for ~3-4% of GEFS+ cases and ~1% of IGE cases (Sun et al. 2008; Audenaert et al. 2006; Lachance-Touchette et al. 2011).
Testing Strategy
This test provides full coverage of all coding exons of the GABRG2 gene, plus ~10 bases of flanking noncoding DNA. We define full coverage as >20X NGS reads or Sanger sequencing.
Indications for Test
Candidates for GABRG2 testing include patients with a family history of febrile seizures that is consistent with autosomal dominant inheritance.
Candidates for GABRG2 testing include patients with a family history of febrile seizures that is consistent with autosomal dominant inheritance.
Gene
| Official Gene Symbol | OMIM ID |
|---|---|
| GABRG2 | 137164 |
| Inheritance | Abbreviation |
|---|---|
| Autosomal Dominant | AD |
| Autosomal Recessive | AR |
| X-Linked | XL |
| Mitochondrial | MT |
Disease
| Name | Inheritance | OMIM ID |
|---|---|---|
| Generalized Epilepsy With Febrile Seizures Plus, Type 3 | AD | 611277 |
Citations
- Audenaert et al. 2006, Neurology 67: 687–690. PubMed ID: 16924025
- Kang JQ et al. 2006. The Journal of Neuroscience : the Official Journal of the Society For Neuroscience. 26: 2590-7. PubMed ID: 16510738
- Lachance-Touchette P et al. 2011. The European Journal of Neuroscience. 34: 237-49. PubMed ID: 21714819
- Sun et al. 2008, Journal of Human Genetics 53: 769–774. PubMed ID: 18566737
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
If ordering a Duo or Trio test, the proband and all comparator samples are required to initiate testing. If we do not receive all required samples for the test ordered within 21 days, we will convert the order to the most effective testing strategy with the samples available. Prior authorization and/or billing in place may be impacted by a change in test code.
Specimen Types
Specimen Requirements and Shipping Details
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ORDER OPTIONS
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2) Select Additional Test Options
No Additional Test Options are available for this test.