Oculocutaneous Albinism Type 3 (OCAIII) via the TYRP1 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 | |
|---|---|---|---|---|---|
| 11785 | TYRP1 | 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. If the phenotype is mainly restricted to the eyes and the optic system, it is referred to as ocular albinism (OA) (Gargiulo et al. 2011). The reduction or complete absence of melanin pigment in the developing eye leads to foveal hypoplasia and misrouting of the optic nerves in the affected individuals (Oetting and King 1999). 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). To date, four types of non-syndromic OCA (type I-IV, based on gene involved) have been described. Their prevalence varies among different populations (Lewis 2013). TYRP1-associated OCA type III also known as rufous OCA (ROCA) prevalence is estimated as 1 in 8,500 (Manga et al. 1997).
Genetics
Mutations in TYRP1 are associated with recessive oculocutaneous albinism type III. TYRP1 is located on chromosome 9 and encodes tyrosinase-related protein 1. This protein appears to be the most abundant melanosomal protein of the melanocyte and is involved in melanocyte proliferation and melanocyte death (Jimbow et al. 1997). TYRP1 is a type I membrane glycoprotein and has ~40% amino acid homology to tyrosinase (encoded by TYR gene) (del Marmol and Beermann 1996). Tyrosinase and TYRP1 catalyze the initial steps in melanin production. TYRP1 is also involved in maintenance of the tyrosinase protein stability and in the regulation of its catalytic activity. Mutations in the TYRP1 protein probably alter the native structural conformation and in turn it's catalytic function (Kamaraj and Purohit 2013). So far, ~20 causative sequence variations (missense, nonsense, small insertions and deletions) have been reported in this gene. Gross deletions have not been reported to date (Human Gene Mutation Database).
Clinical Sensitivity - Sequencing with CNV PGxome
A molecular screening 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 TYRP1 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. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in TYRP1.
All patients with symptoms suggestive of Oculocutaneous albinism are candidates. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in TYRP1.
Gene
| Official Gene Symbol | OMIM ID |
|---|---|
| TYRP1 | 115501 |
| Inheritance | Abbreviation |
|---|---|
| Autosomal Dominant | AD |
| Autosomal Recessive | AR |
| X-Linked | XL |
| Mitochondrial | MT |
Disease
| Name | Inheritance | OMIM ID |
|---|---|---|
| Oculocutaneous Albinism Type 3 | AR | 203290 |
Citations
- del Marmol V, Beermann F. 1996. Tyrosinase and related proteins in mammalian pigmentation. FEBS Lett. 381: 165–168. PubMed ID: 8601447
- 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).
- Jimbow K, Gomez PF, Toyofuku K, Chang D, Miura S, Tsujiya H, Park JS. 1997. Biological role of tyrosinase related protein and its biosynthesis and transport from TGN to stage I melanosome, late endosome, through gene transfection study. Pigment Cell Res. 10: 206–213. PubMed ID: 9263327
- Kamaraj B, Purohit R. 2013. In Silico Screening and Molecular Dynamics Simulation of Disease-Associated nsSNP in TYRP1 Gene and Its Structural Consequences in OCA3. BioMed Research International 2013: 1–13. PubMed ID: 23862152
- 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
- Manga P, Kromberg JGR, Box NF, Sturm RA, Jenkins T, Ramsay M. 1997. Rufous oculocutaneous albinism in southern African Blacks is caused by mutations in the TYRP1 gene. The American Journal of Human Genetics 61: 1095–1101. PubMed ID: 9345097
- 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
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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