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Oguchi Disease and Retinitis Pigmentosa (RP47) via the SAG Gene

Summary and Pricing

Test Method

Exome Sequencing with CNV Detection
Test Code Test Copy GenesTest CPT Code Gene CPT Codes Copy CPT Codes Base Price
8211 SAG 81479 81479,81479 $890 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
8211SAG81479 81479(x2) $890 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 backbone).

Click here for costs to reflex to whole PGnome (if original test is on PGnome Sequencing backbone).

The Sanger Sequencing method for this test is NY State approved.

For Sanger Sequencing click here.

Turnaround Time

18 days on average for standard orders or 13 days 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.

EMAIL CONTACTS

Genetic Counselors

Geneticist

  • Dana Talsness, PhD

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.

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 (includes RPGR ORF15) 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


Specimen Types

Specimen Requirements and Shipping Details

PGxome (Exome) Sequencing Panel

PGnome (Genome) Sequencing Panel

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ORDER OPTIONS

View Ordering Instructions

1) Select Test Method (Backbone)


1) Select Test Type


2) Select Additional Test Options

STAT and Prenatal Test Options are not available with Patient Plus.

No Additional Test Options are available for this test.

Note: acceptable specimen types are whole blood and DNA from whole blood only.
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