Cone-Rod Dystrophy via the KCNV2 Gene
Summary and Pricing 
Test Method
Exome Sequencing with CNV Detection
| Test Code | Test Copy Genes | Test CPT Code | Gene CPT Codes Copy CPT Code | Base Price | |
|---|---|---|---|---|---|
| 8849 | KCNV2 | 81479 | 81479,81479 | $990 | Order Options and Pricing |
Pricing Comments
Our favored testing approach is exome based NextGen sequencing with CNV analysis. This will allow cost effective reflexing to PGxome or other exome based tests. However, if full gene Sanger sequencing is desired for STAT turnaround time, insurance, or other reasons, please see link below for Test Code, pricing, and turnaround time information. If the Sanger option is selected, CNV detection may be ordered through Test #600.
An additional 25% charge will be applied to STAT orders. STAT orders are prioritized throughout the testing process.
Click here for costs to reflex to whole PGxome (if original test is on PGxome Sequencing platform).
Click here for costs to reflex to whole PGnome (if original test is on PGnome Sequencing platform).
The Sanger Sequencing method for this test is NY State approved.
For Sanger Sequencing click here.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
Cone-rod dystrophy (CORD/CRD) is a rare hereditary retinal disorder with a worldwide prevalence of ~1 in 40,000. CRD is characterized by dysfunction or degeneration of cone photoreceptors with relative preservation of rod function in the initial stages. The most common symptoms are photophobia and epiphora in bright light, decreased visual acuity, and dyschromatopsia. Fundus changes may vary from mild pigment granularity to a distinct atrophic lesion in the central macula. As the disease progresses, degeneration of rod photoreceptors also occurs and leads to progressive night blindness and peripheral visual field loss (Hamel 2007).
KCNV2-associated cone dystrophy with supernormal rod electroretinogram (ERG) is an autosomal recessive disorder, which is characterized by reduced visual acuity of variable degree combined with supernormal ERG response to a bright flash of light. Other symptoms include photoaversion, night blindness, and abnormal color vision (Wu et al. 2006; Wissinger et al. 2008).
Genetics
Non syndromic CRD is genetically heterogeneous and exhibits autosomal dominant (ad), autosomal recessive (ar) and, rarely, X-linked (xl) inheritance (Hamel 2007). So far, about 25 genes have been implicated in different forms of CRD (RetNet). Homozygosity mapping in one large consanguineous pedigree with cone dystrophy with supernormal rod response (CDSRR) identified that KCNV2 is involved with autosomal recessive CDSRR. KCNV2 encodes voltage-gated potassium channel Kv8.2 subunit, family V, member 2 (also known as Kv11.1), which is expressed in human photoreceptors and is essential for visual processing and cone survival (Wu et al. 2006; Ottschytsch et al. 2002; Holter et al. 2012; Wissinger et al. 2008). So far about eighty pathogenic variations in KCNV2 have been shown to cause autosomal recessive CDSRR (Human Gene Mutation Database).
Clinical Sensitivity - Sequencing with CNV PGxome
Two different studies have reported KCNV2 mutations in all their patients with cone dystrophy with supernormal rod response (Thiagalingam et al. 2007; Wissinger et al. 2008).
Testing Strategy
This test provides full coverage of all coding exons of the KCNV2 gene plus 10 bases of flanking noncoding DNA in all available transcripts along with other non-coding regions in which pathogenic variants have been identified at PreventionGenetics or reported elsewhere. We define full coverage as >20X NGS reads or Sanger sequencing. PGnome panels typically provide slightly increased coverage over the PGxome equivalent. PGnome sequencing panels have the added benefit of additional analysis and reporting of deep intronic regions (where applicable).
Dependent on the sequencing backbone selected for this testing, discounted reflex testing to any other similar backbone-based test is available (i.e., PGxome panel to whole PGxome; PGnome panel to whole PGnome).
Indications for Test
All patients with symptoms suggestive of Cone-rod dystrophy. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in KCNV2.
All patients with symptoms suggestive of Cone-rod dystrophy. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in KCNV2.
Gene
| Official Gene Symbol | OMIM ID |
|---|---|
| KCNV2 | 607604 |
| Inheritance | Abbreviation |
|---|---|
| Autosomal Dominant | AD |
| Autosomal Recessive | AR |
| X-Linked | XL |
| Mitochondrial | MT |
Disease
| Name | Inheritance | OMIM ID |
|---|---|---|
| Retinal Cone Dystrophy 3B | AR | 610356 |
Citations
- Hamel CP. 2007. Cone rod dystrophies. Orphanet J Rare Dis 1;2:7. PubMed ID: 17270046
- Holter P, Kunst S, Wolloscheck T, Kelleher DK, Sticht C, Wolfrum U, Spessert R. 2012. The Retinal Clock Drives the Expression of Kcnv2, a Channel Essential for Visual Function and Cone Survival. Investigative Ophthalmology & Visual Science 53: 6947–6954. PubMed ID: 22969075
- Human Gene Mutation Database (Bio-base).
- Ottschytsch N, Raes A, Hoorick D Van, Snyders DJ. 2002. Obligatory heterotetramerization of three previously uncharacterized Kv channel α-subunits identified in the human genome. Proceedings of the National Academy of Sciences 99: 7986–7991. PubMed ID: 12060745
- Thiagalingam S, McGee TL, Weleber RG, Sandberg MA, Trzupek KM, Berson EL, Dryja TP. 2007. Novel mutations in the KCNV2 gene in patients with cone dystrophy and a supernormal rod electroretinogram. Ophthalmic Genet. 28: 135–142. PubMed ID: 17896311
- Wissinger B, Dangel S, Jägle H, Hansen L, Baumann B, Rudolph G, Wolf C, Bonin M, Koeppen K, Ladewig T, others. 2008. Cone dystrophy with supernormal rod response is strictly associated with mutations in KCNV2. Investigative ophthalmology & visual science 49: 751–757. PubMed ID: 18235024
- Wu H, Cowing JA, Michaelides M, Wilkie SE, Jeffery G, Jenkins SA, Mester V, Bird AC, Robson AG, Holder GE, others. 2006. Mutations in the Gene KCNV2 Encoding a Voltage-Gated Potassium Channel Subunit Cause “Cone Dystrophy with Supernormal Rod Electroretinogram” in Humans. The American Journal of Human Genetics 79: 574–579. PubMed ID: 16909397
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
PGxome (Exome) Sequencing Panel
PGnome (Genome) Sequencing Panel
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ORDER OPTIONS
View Ordering Instructions1) Select Test Type
2) Select Additional Test Options
No Additional Test Options are available for this test.