Achromatopsia via the CNGB3 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 | |
|---|---|---|---|---|---|
| 6917 | CNGB3 | 81479 | 81479,81479 | $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
Achromatopsia is a congenital cone rod dystrophy (CRD) that can be distinguished from other CRDs on the basis of primary cone involvement, stationary course, and normal fundus (Hamel Orphanet J Rare Dis 2:7, 2007). Two clinical types of achromatopsia, complete and incomplete, are recognized. In patients with complete achromatopsia, symptoms usually begin in infancy and include nystagmus, low visual acuity, photophobia, severe color vision defects, and selective absence of functioning cone photoreceptor cells in electroretinogram (ERG) findings. Patients with incomplete achromatopsia retain residual functioning cone cells. In addition, they have mild visual acuity and mild color vision defects. The prevalence of complete achromatopsia is 1 per 30,000 people worldwide (Michaelides et al. Br J Ophthalmol 88 291–297, 2004). However, in the Micronesian atoll of Pingelap, achromatopsia affects ~ 5 % of the island population (Morton et al. Am J Hum Genet 24:277-289, 1972).
Genetics
Achromatopsia is a heterogeneous genetic disease that is inherited in an autosomal recessive manner. It is caused by defects in various genes that encode important elements of the cone phototransduction process. Variants in four genes, including CNGB3 (Sundin et al. Nat Genet 25:289-293, 2000), have been identified in patients with achromatopsia. At least 37 different CNGB3 causative variants have been reported. Most variants are expected to result in truncated proteins and include nonsense and splice site variants and small insertions, deletions, and indels. Only three missense variants have been reported to date. No large deletions, duplications, or complex rearrangements have been reported. A founder missense variant, c.1304C>T, causes achromatopsia in the Pingelap population (Sundin, 2000). In addition to achromatopsia (OMIM 262300), CNGB3 variants were identified in patients with juvenile onset macular degeneration (OMIM 248200; Nishiguchi et al. Hum Mutat 25:248-258, 2005) and patients with progressive cone dystrophy (Michaelides et al. Invest Ophthalmol Vis Sci 45:1975-1982, 2004).
The CNGB3 gene encodes the beta subunit of the cyclic nucleotide-gated cation channel in cone photoreceptor cells.
Clinical Sensitivity - Sequencing with CNV PG-Select
This test will detect variants in up to 50% of patients with clinical diagnosis of achromatopsia (Kohl et al. Eur J Hum Genet13:302-308, 2005).
Testing Strategy
This test provides full coverage of all coding exons of the CNGB3 gene, plus ~10 bases of flanking noncoding DNA. We define full coverage as >20X NGS reads or Sanger sequencing.
Indications for Test
Patients with normal rod function and absence of cone response in ERG findings (Kohl et al. GeneReviews, 2009). This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in CNGB3.
Patients with normal rod function and absence of cone response in ERG findings (Kohl et al. GeneReviews, 2009). This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in CNGB3.
Gene
| Official Gene Symbol | OMIM ID |
|---|---|
| CNGB3 | 605080 |
| Inheritance | Abbreviation |
|---|---|
| Autosomal Dominant | AD |
| Autosomal Recessive | AR |
| X-Linked | XL |
| Mitochondrial | MT |
Diseases
| Name | Inheritance | OMIM ID |
|---|---|---|
| Achromatopsia 3 | AR | 262300 |
| Stargardt Disease 1 | AR | 248200 |
Related Tests
| Name |
|---|
| Cone-Rod Dystrophy Panel |
| Flecked Retina Disorder Panel |
| Leber Congenital Amaurosis Panel |
Citations
- Hamel CP. 2007. Cone rod dystrophies. Orphanet J Rare Dis 1;2:7. PubMed ID: 17270046
- Kohl et al. 2015. Achromatopsia. In: Pagon RA, Adam MP, Bird TD, Dolan CR, Fong C-T, Smith RJ, and Stephens K, editors. GeneReviews™, Seattle (WA): University of Washington, Seattle. PubMed ID: 20301591
- Kohl S. et al. 2005. European Journal of Human Genetics: Ejhg. 13: 302-8. PubMed ID: 15657609
- Michaelides, M., et.al. (2004). "Progressive cone dystrophy associated with mutation in CNGB3." Invest Ophthalmol Vis Sci 45(6): 1975-82. PubMed ID: 15161866
- Michaelides, M., et.al. (2004). "The cone dysfunction syndromes." Br J Ophthalmol 88(2): 291-7. PubMed ID: 14736794
- Nishiguchi, K. M., et.al. (2005). "Cone cGMP-gated channel mutations and clinical findings in patients with achromatopsia, macular degeneration, and other hereditary cone diseases." Hum Mutat 25(3): 248-58. PubMed ID: 15712225
- Strauss, K. A., Morton, D. H. (2003). "Type I glutaric aciduria, part 2: a model of acute striatal necrosis." Am J Med Genet C Semin Med Genet 121C(1): 53-70. PubMed ID: 12888986
- Sundin O.H. et al. 2000. Nature Genetics. 25: 289-93. PubMed ID: 10888875
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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