Ocular Albinism (OA1) via the GPR143 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 | |
|---|---|---|---|---|---|
| 11363 | GPR143 | 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.
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
Oculocutaneous albinism (OCA) is an inherited disorder caused by deficiency in melanin synthesis that results in hypopigmentation of the skin, eyes, and hair (Gargiulo et al. 2011). To date, four types of non-syndromic OCA (type I-IV, based on gene involved) have been described, and their prevalence varies among different populations (Lewis 2013). The eye and optic system abnormalities that are common to all types of albinism are nystagmus, photophobia, strabismus, moderate to severe impairment of visual acuity, reduced iris pigment with iris translucency, reduced retinal pigment with visualization of the choroidal blood vessels on ophthalmoscopic examination, refractive errors and altered visual evoked potentials (VEP). The degree of skin and hair hypopigmentation varies with the type of OCA, but the ocular phenotype does not change (Lewis 2012).X-linked recessive ocular albinism type 1 (OA1) mainly effects pigment production in the eye (known as incomplete albinism) that results in foveal hypoplasia, reduced visual acuity and misrouting of the optic nerves in the affected individuals (Oetting 2002; Oetting and King 1999). Estimated prevalence of OA1 is 1:60 000 live-births (Rosenberg and Schwartz 1998). Female carriers have normal vision. However, they show a characteristic 'mud splattered' fundus appearance (Schiaffino and Tacchetti 2005).
Genetics
Mutations in GPR143 cause X-linked recessive ocular albinism type 1. GPR143 is located on chromosome Xp22.32, and encodes an integral transmembrane glycoprotein that has weak structural and functional homology with G protein-coupled receptors (GPCRs). Unlike GPCRs, GPR143 is located in intracellular organelles, such as late endosomes/lysosomes and melanosomes and is involved in the regulation of melanosome biogenesis by intracellular signal transduction (Schiaffino and Tacchetti 2005; Palmisano et al. 2008). So far, over 100 causative sequence variations (missense, nonsense, splicing, small insertions and deletions) have been reported in this gene and gross deletions are also commonly reported (Human Gene Mutation Database; Schnur et al. 1998).
Clinical Sensitivity - Sequencing with CNV PGxome
A mutation screening of 29 unrelated North American and Australian X-linked ocular albinism (OA) probands, detected GPR143 mutations in approximately 90% of the probands. Over 40% 0f the probands had gross deletions in this gene (Schnur et al. 1998). A molecular screening of the TYR, OCA2, TYRP1, SLC45A2 genes in 121 unrelated non-Hispanic/Latino White OCA patients identified mutations in TYR (69%), OCA2 (18%), SLC45A2 (6%), and no apparent pathological mutations in 7% of patients (Hutton and Spritz 2008). These results indicate the heterogeneity of this disorder. Another study in Chinese OCA patients identified mutations in TYR (36%), OCA2 (25%), TYRP1(2%), SLC45A2 (11%) and GPR143 (6%) (Morice-Picard et al. 2014).
Testing Strategy
This test provides full coverage of all coding exons of the GPR143 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 Oculocutaneous albinism are candidates.
All patients with symptoms suggestive of Oculocutaneous albinism are candidates.
Gene
| Official Gene Symbol | OMIM ID |
|---|---|
| GPR143 | 300808 |
| Inheritance | Abbreviation |
|---|---|
| Autosomal Dominant | AD |
| Autosomal Recessive | AR |
| X-Linked | XL |
| Mitochondrial | MT |
Diseases
| Name | Inheritance | OMIM ID |
|---|---|---|
| Nystagmus 6, Congenital, X-Linked | 300814 | |
| Ocular Albinism, Type I | XL | 300500 |
Citations
- Gargiulo A, Testa F, Rossi S, Iorio V Di, Fecarotta S, Berardinis T de, Iovine A, Magli A, Signorini S, Fazzi E. 2011. Molecular and clinical characterization of albinism in a large cohort of Italian patients. Investigative Ophthalmology & Visual Science 52: 1281–1289. PubMed ID: 20861488
- Human Gene Mutation Database (Bio-base).
- Hutton SM, Spritz RA. 2008. Comprehensive Analysis of Oculocutaneous Albinism among Non-Hispanic Caucasians Shows that OCA1 Is the Most Prevalent OCA Type. Journal of Investigative Dermatology 128: 2442–2450. PubMed ID: 18463683
- Lewis RA. 2012. Oculocutaneous Albinism Type 2. In: Pagon RA, Adam MP, Bird TD, Dolan CR, Fong C-T, and Stephens K, editors. GeneReviews™, Seattle (WA): University of Washington, Seattle. PubMed ID: 20301410
- Lewis RA. 2013. Oculocutaneous Albinism Type 1. 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: 20301345
- Morice-Picard F, Lasseaux E, François S, Simon D, Rooryck C, Bieth E, Colin E, Bonneau D, Journel H, Walraedt S, Leroy BP, Meire F, Lacombe D, Arveiler B. 2014. SLC24A5 Mutations Are Associated with Non-Syndromic Oculocutaneous Albinism. J Invest Dermatol 134: 568–571. PubMed ID: 23985994
- Oetting WS, King RA. 1999. Molecular basis of albinism: mutations and polymorphisms of pigmentation genes associated with albinism. Hum. Mutat. 13: 99–115. PubMed ID: 10094567
- Oetting WS. 2002. New insights into ocular albinism type 1 (OA1): Mutations and polymorphisms of the OA1 gene. Human Mutation 19: 85–92. PubMed ID: 11793467
- Palmisano I, Bagnato P, Palmigiano A, Innamorati G, Rotondo G, Altimare D, Venturi C, Sviderskaya EV, Piccirillo R, Coppola M, Marigo V, Incerti B, et al. 2008. The ocular albinism type 1 protein, an intracellular G protein-coupled receptor, regulates melanosome transport in pigment cells. Human Molecular Genetics 17: 3487–3501. PubMed ID: 18697795
- Rosenberg T, Schwartz M. 1998. X-linked ocular albinism: prevalence and mutations-a national study. European Journal of Human Genetics 6: 570–577. PubMed ID: 9887374
- Schiaffino MV, Tacchetti C. 2005. The ocular albinism type 1 (OA1) protein and the evidence for an intracellular signal transduction system involved in melanosome biogenesis: OA1 and signal transduction at internal membranes. Pigment Cell Research 18: 227–233. PubMed ID: 16029416
- Schnur RE, Gao M, Wick PA, Keller M, Benke PJ, Edwards MJ, Grix AW, Hockey A, Jung JH, Kidd KK, others. 1998. OA1 mutations and deletions in X-linked ocular albinism. The American Journal of Human Genetics 62: 800–809. PubMed ID: 9529334
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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