Oguchi Disease and Retinitis Pigmentosa (RP47) via the SAG 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 | |
|---|---|---|---|---|---|
| 8211 | SAG | 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
Oguchi disease (OD) is a rare autosomal recessive form of congenital stationary night blindness. OD is clinically characterized by typical golden yellow discoloration of the fundus (first described in Japanese population as Mizuo-Nakamura phenomenon) and extremely slow dark adaptation. Other visual functions such as visual acuity, visual field, and colour vision are usually normal (Fuchs et al. 1995).
Retinitis pigmentosa (RP) represents a group of hereditary retinal dystrophies with a worldwide prevalence of ~1 in 4000 (Booij 2005). RP is clinically characterized by retinal pigment deposits visible on fundus examination, nyctalopia ("night blindness"), followed by progressive degeneration of the photoreceptors, which eventually leads to blindness (van Soest et al. 1999).
Genetics
Mutations in SAG cause autosomal recessive Oguchi disease and retinitis pigmentosa. So far two genes, SAG and GRK1, have been implicated in Oguchi disease. SAG-associated OD is classified as type 1 and GRK1-associated OD as type 2 (Waheed et al. 2012). SAG, which is located on chromosome 2 (Fuchs et al. 1995) encodes S-antigen (also known as arrestin) protein, which may be involved in the recovery phase of the phototransduction cascade. SAG is a soluble protein expressed in the retina, specifically in the rod photoreceptor cell outer segment also in and pinealocytes (Yamaki et al. 1990). It has been suggested that SAG binds to phosphorylated activated rhodopsin (Rh*) and stabilizes Rh*. This process impedes the regeneration of native rhodopsin, which suggests that SAG serves as a switch that shuts down light-induced activity of Rh* (Maw et al. 1995; Wilden et al. 1986). So far, about 15 mutations (missense/nonsense, small and gross deletions) have been reported in SAG that are involved with OD and RP (Human Gene Mutation Database). SAG is reported to be a frequent cause of OD in the Japanese population, often due to a founder mutation c.926delA (p.Asn309Thrfs*12) (Fuchs et al. 1995).
Clinical Sensitivity - Sequencing with CNV PGxome
SAG is reported to be a frequent cause of OD in the Japanese population (Fuchs et al. 1995). Clinical sensitivity cannot be precisely estimated due to a small number of patients in the reported studies. Analytical sensitivity should be high because majority of the mutations reported are detectable by this method. Gross deletions and duplications have been reported in the SAG gene (Human Gene Mutation Database).
Testing Strategy
This test provides full coverage of all coding exons of the SAG 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 Oguchi disease or Retinitis pigmentosa are candidates. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in SAG.
All patients with symptoms suggestive of Oguchi disease or Retinitis pigmentosa are candidates. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in SAG.
Gene
| Official Gene Symbol | OMIM ID |
|---|---|
| SAG | 181031 |
| Inheritance | Abbreviation |
|---|---|
| Autosomal Dominant | AD |
| Autosomal Recessive | AR |
| X-Linked | XL |
| Mitochondrial | MT |
Disease
| Name | Inheritance | OMIM ID |
|---|---|---|
| Retinitis Pigmentosa 47 | AR | 613758 |
Related Test
| Name |
|---|
| Retinitis Pigmentosa Panel |
Citations
- Booij JC. 2005. Identification of mutations in the AIPL1, CRB1, GUCY2D, RPE65, and RPGRIP1 genes in patients with juvenile retinitis pigmentosa. Journal of Medical Genetics 42: e67–e67. PubMed ID: 16272259
- Fuchs S, Nakazawa M, Maw M, Tamai M, Oguchi Y, Gal A. 1995. A homozygous 1-base pair deletion in the arrestin gene is a frequent cause of Oguchi disease in Japanese. Nat. Genet. 10: 360–362. PubMed ID: 7670478
- Human Gene Mutation Database (Bio-base).
- Maw MA, John S, Jablonka S, Müller B, Kumaramanickavel G, Oehlmann R, Denton MJ, Gal A. 1995. Oguchi disease: suggestion of linkage to markers on chromosome 2q. Journal of medical genetics 32: 396–398. PubMed ID: 7616550
- van Soest S, Westerveld A, Jong PT de, Bleeker-Wagemakers EM, Bergen AA. 1999. Retinitis pigmentosa: defined from a molecular point of view. Surv Ophthalmol 43: 321–334. PubMed ID: 10025514
- Waheed NK, Qavi AH, Malik SN, Maria M, Riaz M, Cremers FPM, Azam M, Qamar R. 2012. A nonsense mutation in S-antigen (p.Glu306*) causes Oguchi disease. Mol Vis 18: 1253–1259. PubMed ID: 22665972
- Wilden U, Hall SW, Kühn H. 1986. Phosphodiesterase activation by photoexcited rhodopsin is quenched when rhodopsin is phosphorylated and binds the intrinsic 48-kDa protein of rod outer segments. Proceedings of the National Academy of Sciences 83: 1174–1178. PubMed ID: 3006038
- Yamaki K, Tsuda M, Kikuchi T, Chen KH, Huang KP, Shinohara T. 1990. Structural organization of the human S-antigen gene. cDNA, amino acid, intron, exon, promoter, in vitro transcription, retina, and pineal gland. Journal of Biological Chemistry 265: 20757–20762. PubMed ID: 2249983
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
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2) Select Additional Test Options
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