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Oculocutaneous Albinism in Griscelli syndrome via the MYO5A 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
11497 MYO5A 81479 81479,81479 $890 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
11497MYO5A81479 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.

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

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). 

Clinical findings of hypopigmentation of the skin and hair, in addition to the characteristic ocular symptoms are present in many syndromic disorders for e.g., Griscelli syndrome (GS) (Ménasché et al. 2000; Pastural et al. 1997). MYO5A-associated GS is described as characteristic albinism with a severe developmental delay and mental retardation that occurs early in life (Ménasché et al. 2000).

Genetics

Mutations in MYO5A gene, which encodes an actin-based molecular motor protein Myosin Va (MyoVa) are associated with recessive GS (Pastural et al. 1997). It has been reported that the MYO5A encoded protein has a role in neuron function (Miyata et al. 2011). Myosin Va is recruited on to diverse organelles, such as melanosomes and secretory vesicles and is involved in short-range axonal/dendritic transport (Langford 2002; Brown et al. 2004), which explains the developmental delay in the GS patients. Very few causative mutations (nonsense and gross insertions and deletions) with limited cases have been reported in this gene (Human Gene Mutation Database). 

Clinical Sensitivity - Sequencing with CNV PGxome

Predicting clinical sensitivity for the MYO5A gene is challenging due to genetic heterogeneity of Oculocutaneous albinism and the limited number of cases reported with MYO5A-associated Griscelli syndrome.

Testing Strategy

This test provides full coverage of all coding exons of the MYO5A 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 with developmental delay are candidates. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in MYO5A.

Gene

Official Gene Symbol OMIM ID
MYO5A 160777
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Disease

Name Inheritance OMIM ID
Griscelli Syndrome Type 1 AR 214450

Citations

  • Brown JR, Stafford P, Langford GM. 2004. Short-range axonal/dendritic transport by myosin-V: A model for vesicle delivery to the synapse. J. Neurobiol. 58: 175–188. PubMed ID: 14704950
  • 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).
  • Langford GM. 2002. Myosin-V, a versatile motor for short-range vesicle transport. Traffic 3: 859–865. PubMed ID: 12453149
  • 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
  • Ménasché G, Pastural E, Feldmann J, Certain S, Ersoy F, Dupuis S, Wulffraat N, Bianchi D, Fischer A, Deist F Le, Saint Basile G de. 2000. Mutations in RAB27A cause Griscelli syndrome associated with haemophagocytic syndrome. Nat. Genet. 25: 173–176. PubMed ID: 10835631
  • Miyata M, Kishimoto Y, Tanaka M, Hashimoto K, Hirashima N, Murata Y, Kano M, Takagishi Y. 2011. A Role for Myosin Va in Cerebellar Plasticity and Motor Learning: A Possible Mechanism Underlying Neurological Disorder in Myosin Va Disease. Journal of Neuroscience 31: 6067–6078. PubMed ID: 21508232
  • 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
  • Pastural E, Barrat FJ, Dufourcq-Lagelouse R, Certain S, Sanal O, Jabado N, Seger R, Griscelli C, Fischer A, Saint Basile G de. 1997. Griscelli disease maps to chromosome 15q21 and is associated with mutations in the myosin-Va gene. Nat. Genet. 16: 289–292. PubMed ID: 9207796

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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