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Achromatopsia via the PDE6C 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
11561 PDE6C 81479 81479,81479 $990 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
11561PDE6C81479 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. 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 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.

EMAIL CONTACTS

Genetic Counselors

Geneticist

  • Dana Talsness, PhD

Clinical Features and Genetics

Clinical Features

Achromatopsia is a congenital cone rod dystrophy (CRD) that can be distinguished from other CRDs on the basis of primary cone involvement, stationary course, and normal fundus (Hamel Orphanet J Rare Dis 2:7, 2007).  Two clinical types of achromatopsia, complete and incomplete, are recognized.  In patients with complete achromatopsia, symptoms usually begin in infancy and include nystagmus, low visual acuity, photophobia, severe color vision defects, and selective absence of functioning cone photoreceptor cells in electroretinogram (ERG) findings.  Patients with incomplete achromatopsia retain residual functioning cone cells.  In addition, they have mild visual acuity and mild color vision defects.  The prevalence of complete achromatopsia is 1 per 30,000 people worldwide (Michaelides et al. Br J Ophthalmol 88 291–297, 2004).  However, in the Micronesian atoll of Pingelap, achromatopsia affects ~ 5 % of the island population (Morton et al. Am J Hum Genet 24:277-289, 1972).

Genetics

Achromatopsia is a heterogeneous genetic disease inherited in an autosomal recessive manner. It is caused by defects in various genes that encode important elements of the cone phototransduction process. Variants in four genes, including PDE6C (Chang et al. Proc Natl Acad Sci USA 106:19581-19586, 2009; Thiadens et al. Am J Hum Genet 85:240-247, 2009), have been identified in patients with achromatopsia. To date, ~15 different PDE6C causative variants have been reported. Variants include missense, nonsense, splicing, and small insertions or deletions. No large deletions, duplications, or complex rearrangements have been reported. In addition to achromatopsia, PDE6C variants were identified in patients with autosomal recessive, early-onset progressive cone dystrophy (arCD), suggesting that ACHM and arCD are clinically and genetically overlapping disorders (Thiadens et al. 2009). The PDE6C gene encodes the alpha subunit of phosphodiesterase in cone photoreceptor cells.

Clinical Sensitivity - Sequencing with CNV PGxome

About 2% of achromatopsia patients with known causative variants have variants in PDE6C (Thiadens et al. Am J Hum Genet 85:240-247, 2009).

Testing Strategy

This test provides full coverage of all coding exons of the PDE6C 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

Patients with normal rod response and absence of cone response in ERG findings, and no variants in the CNGB3, CNGA3, and GNAT2 genes (Kohl et al. GeneReviews, 2010). This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in PDE6C.

Gene

Official Gene Symbol OMIM ID
PDE6C 600827
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Disease

Name Inheritance OMIM ID
Cone Dystrophy 4 AR 613093

Citations

  • Chang, B., et.al. (2009). "A homologous genetic basis of the murine cpfl1 mutant and human achromatopsia linked to mutations in the PDE6C gene." Proc Natl Acad Sci U S A 106(46): 19581-6. PubMed ID: 19887631
  • Hamel CP. 2007. Cone rod dystrophies. Orphanet J Rare Dis 1;2:7. PubMed ID: 17270046
  • Kohl et al. 2015. Achromatopsia. 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: 20301591
  • Michaelides, M., et.al. (2004). "The cone dysfunction syndromes." Br J Ophthalmol 88(2): 291-7. PubMed ID: 14736794
  • Morton, N. E., et.al. (1972). "Pingelap and Mokil Atolls: historical genetics." Am J Hum Genet 24(3): 277-89. PubMed ID: 4537352
  • Thiadens, A. A., et.al. (2009). "Homozygosity mapping reveals PDE6C mutations in patients with early-onset cone photoreceptor disorders." Am J Hum Genet 85(2): 240-7. PubMed ID: 19615668

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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View Ordering Instructions

1) Select Test Method (Platform)


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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