Retinitis Pigmentosa via the CNGA1 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 | |
|---|---|---|---|---|---|
| 9951 | CNGA1 | 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
Nonsyndromic retinitis pigmentosa (RP, OMIM # 268000) is a large group of inherited degenerative diseases of the retina characterized by abnormalities of the photoreceptors or the retinal pigment epithelium. It is a progressive disease. Symptoms usually begin with night blindness, progressing to constriction of the peripheral visual field and, eventually, to loss of central vision. The age of onset varies from childhood to middle age (Gu et al. J Med Genet 36:705-707, 1999). The clinical hallmarks are abnormal fundus with bone-spicule deposits and attenuated retinal vessels, abnormal electroretinographic findings, and reduced visual fields (Daiger et al. Arch Ophthalmol 125:151-158, 2007). RP affects 1 in 3,000 people worldwide (Farrar et al. EMBO J 21:857-864, 2002). Genetic abnormalities are the primary cause of RP, which affects all ethnic groups.
Genetics
Retinitis pigmentosa (RP) is genetically and clinically heterogeneous (Koenekoop et al. Clin Experiment Ophthalmol 35:473-485, 2007). At least 4 distinct subgroups are recognized on the basis of the mode of inheritance and age of onset. These include autosomal dominant (AD-RP), autosomal recessive (AR-RP), X-linked, and digenic (Kajiwara et al. Science 264:1604-1608, 1994). In addition, RP can be inherited as a mitochondrial trait (Mansergh et al. Am J Hum Genet 64:971-985, 1999). Genetic heterogeneity is documented within each subgroup. Currently, 23 genes are known to cause AR-RP. These include the CNGA1 gene (Dryja et al. Proc Natl Acad Sci USA 92:10177-10181, 1995). At least 7 different CNGA1 variants have been implicated in AR-RP to date. Reported variants consisted of 3 nonsense, 2 missense, and 2 small deletions; they occurred in patients of various ethnic groups, including Spanish, Pakistani and Japanese (Paloma et al. J Med Genet 39:E66, 2002; Zhang et al. Mol Vis 10:884-889, 2004; Jin et al. J Med Genet 45:465-472, 2008).
The CNGA1 gene encodes the alpha subunit of the rod photoreceptor cyclic nucleotide gated channel (CNG) that mediates visual transduction in retinal rods.
Clinical Sensitivity - Sequencing with CNV PGxome
Variants in the CNGA1 gene account for ~2% of patients with AR-RP (Dryja et al. Proc Natl Acad Sci USA 92:10177-10181, 1995).
Testing Strategy
This test provides full coverage of all coding exons of the CNGA1 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
Patients with AR-RP and suspected heterozygous carriers. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in CNGA1.
Patients with AR-RP and suspected heterozygous carriers. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in CNGA1.
Gene
| Official Gene Symbol | OMIM ID |
|---|---|
| CNGA1 | 123825 |
| Inheritance | Abbreviation |
|---|---|
| Autosomal Dominant | AD |
| Autosomal Recessive | AR |
| X-Linked | XL |
| Mitochondrial | MT |
Disease
| Name | Inheritance | OMIM ID |
|---|---|---|
| Retinitis Pigmentosa 49 | 613756 |
Citations
- Daiger et al. 2007. PubMed ID: 17296890
- Dryja, T. P., et.al. (1995). "Mutations in the gene encoding the alpha subunit of the rod cGMP-gated channel in autosomal recessive retinitis pigmentosa." Proc Natl Acad Sci U S A 92(22): 10177-81. PubMed ID: 7479749
- Dryja, T. P., et.al. (1995). "Mutations in the gene encoding the alpha subunit of the rod cGMP-gated channel in autosomal recessive retinitis pigmentosa." Proc Natl Acad Sci U S A 92(22): 10177-81. PubMed ID: 7479749
- Farrar, G. J., et.al. (2002). "On the genetics of retinitis pigmentosa and on mutation-independent approaches to therapeutic intervention." Embo J 21(5): 857-64. PubMed ID: 11867514
- Gu S. et al. 1999. Journal of Medical Genetics. 36: 705-7. PubMed ID: 10507729
- Jin, Z. B., et.al. (2008). "Identifying pathogenic genetic background of simplex or multiplex retinitis pigmentosa patients: a large scale mutation screening study." J Med Genet 45(7): 465-72. PubMed ID: 18310263
- Kajiwara, K. et.al. (1994). "Digenic retinitis pigmentosa due to mutations at the unlinked peripherin/RDS and ROM1 loci." Science 264(5165): 1604-1608. PubMed ID: 8202715
- Koenekoop, R. K., et.al. (2007). "Genetic testing for retinal dystrophies and dysfunctions: benefits, dilemmas and solutions." Clin Experiment Ophthalmol 35(5): 473-85. PubMed ID: 17651254
- Mansergh, F. C., et.al. (1999). "Retinitis pigmentosa and progressive sensorineural hearing loss caused by a C12258A mutation in the mitochondrial MTTS2 gene." Am J Hum Genet 64(4): 971-85. PubMed ID: 10090882
- Paloma, E., et.al. (2002). "Novel homozygous mutation in the alpha subunit of the rod cGMP gated channel (CNGA1) in two Spanish sibs affected with autosomal recessive retinitis pigmentosa." J Med Genet 39(10): E66. PubMed ID: 12362048
- Zhang, Q., et.al. (2004). "Autosomal recessive retinitis pigmentosa in a Pakistani family mapped to CNGA1 with identification of a novel mutation." Mol Vis 10: 884-9. PubMed ID: 15570217
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.