Oculocutaneous Albinism Type 4 (OCAIV) via the SLC45A2 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 | |
|---|---|---|---|---|---|
| 11681 | SLC45A2 | 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). OCAIV accounts for 17% of the total OCA cases worldwide and is one of the most prevalent types in Japan (Inagaki et al. 2004).
Genetics
Mutations in SLC45A2 [solute carrier family 45, member 2 gene, previously known as membrane-associated transporter protein (MATP)] are associated with recessive oculocutaneous albinism type IV (one of the major sub types) (Simeonov et al. 2013). It has been reported that the melanosomal membrane localized SLC45A2 protein has a critical role in vertebrate pigmentation, by mediating the transport of an essential substance across the membrane (Newton et al. 2001). A study showed that substantial reduction of the SLC45A2 protein in the patient’s melanocytes caused the mis-localization of tyrosinase (encoded by TYR gene) from melanosomes (Simeonov et al. 2013). So far, over 80 causative sequence variations (missense, nonsense, splicing, small and gross insertions and deletions) have been reported in this gene (Human Gene Mutation Database). In approximately ~30% (12/39) of OCAIV cases the second mutation was not identified in the SLC45A2 gene, which could be due to mutations in the distal promoter or deep intronic regions or possibly mutations in another locus currently unknown (Sengupta et al. 2007).
Clinical Sensitivity - Sequencing with CNV PGxome
In molecular screenings, 11% of the Chinese OCA patients (Morice-Picard et al. 2014), 3.4% of Italian patients (Mauri et al. 2014), 10% of the eastern and southern India OCA patients (Sengupta et al. 2007) and 24% of Japanese patients (Inagaki et al. 2004) had SLC45A2 causative mutations.
Testing Strategy
This test provides full coverage of all coding exons of the SLC45A2 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 SLC45A2.
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 SLC45A2.
Gene
| Official Gene Symbol | OMIM ID |
|---|---|
| SLC45A2 | 606202 |
| Inheritance | Abbreviation |
|---|---|
| Autosomal Dominant | AD |
| Autosomal Recessive | AR |
| X-Linked | XL |
| Mitochondrial | MT |
Disease
| Name | Inheritance | OMIM ID |
|---|---|---|
| Oculocutaneous Albinism Type IV | 606574 |
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).
- Inagaki K, Suzuki T, Shimizu H, Ishii N, Umezawa Y, Tada J, Kikuchi N, Takata M, Takamori K, Kishibe M, Tanaka M, Miyamura Y, Ito S, Tomita Y. 2004. Oculocutaneous albinism type 4 is one of the most common types of albinism in Japan. The American Journal of Human Genetics 74: 466–471. PubMed ID: 14961451
- 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
- Mauri L, Barone L, Oum M Al, Longo A Del, Piozzi E, Manfredini E, Stanzial F, Benedicenti F, Penco S, Patrosso MC. 2014. SLC45A2 mutation frequency in Oculocutaneous Albinism Italian patients doesn’t differ from other European studies. Gene 533: 398–402. PubMed ID: 24096233
- 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
- Newton JM, Cohen-Barak O, Hagiwara N, Gardner JM, Davisson MT, King RA, Brilliant MH. 2001. Mutations in the human orthologue of the mouse underwhite gene (uw) underlie a new form of oculocutaneous albinism, OCA4. The American Journal of Human Genetics 69: 981–988. PubMed ID: 11574907
- 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
- Sengupta M, Chaki M, Arti N, Ray K. 2007. SLC45A2 variations in Indian oculocutaneous albinism patients. Mol. Vis 13: 1406–1411. PubMed ID: 17768386
- Simeonov DR, Wang X, Wang C, Sergeev Y, Dolinska M, Bower M, Fischer R, Winer D, Dubrovsky G, Balog JZ, Huizing M, Hart R, Zein WM, Gahl WA, Brooks BP, Adams DR. 2013. DNA Variations in Oculocutaneous Albinism: An Updated Mutation List and Current Outstanding Issues in Molecular Diagnostics. Human Mutation 34: 827–835. PubMed ID: 23504663
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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