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Cone-Rod Dystrophy 20 via the POC1B 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
10637 POC1B 81479 81479,81479 $990 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
10637POC1B81479 81479,81479 $990 Order Options and Pricing

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).

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

Cone-rod dystrophy (CORD/CRD) is a rare hereditary retinal disorder with a worldwide prevalence of ~1 in 40,000. CRD is characterized by dysfunction or degeneration of cone photoreceptors with relative preservation of rod function in the initial stages. The most common symptoms are photophobia and epiphora in bright light, decreased visual acuity, and dyschromatopsia. Fundus changes may vary from mild pigment granularity to a distinct atrophic lesion in the central macula. As the disease progresses, degeneration of rod photoreceptors also occurs and leads to progressive night blindness and peripheral visual field loss (Hamel. 2007. PubMed ID: 17270046).

Genetics

Non syndromic CRD is genetically heterogeneous and exhibits autosomal dominant (AD), autosomal recessive (AR) and, rarely, X-linked (XL) inheritance (Hamel. 2007. PubMed ID: 17270046). To date, over 25 genes have been implicated in different forms of CRD (RetNet). Causative variants in the genes ABCA4, ADAM9, AIPL1, C21orf2, C8orf37, CABP4, CACNA2D4, CDHR1, CERKL, CNGB3, CNNM4, DRAM2, KCNV2, PDE6C, POC1B, RAB28, RPGRIP1, RGS9, RGS9BP and TTLL5 are inherited in an AR manner. Causative variants in the genes CRX, GUCA1A, GUCY2D, PITPNM3, RAX2, RIMS1, SEMA4A, UNC119 show AD inheritance. Pathogenic variants in BEST1, PDE6H, PROM1 and PRPH2 are inherited in both AD and AR manner. CACNA1F and RPGR are the only genes associated with XL-CRD in male patients. Due to the genetic heterogeneity, screening of all the CRD-associated genes is recommended. Most of the CRD-associated genes are also involved in other types of retinal dystrophies such as Retinitis Pigmentosa, macular dystrophies and cone dystrophies. Many of these genes encode proteins that have major roles in disc morphogenesis and the membrane- trafficking of photoreceptors (Sung and Chuang. 2010. PubMed ID: 20855501).

Bi-allelic pathogenic variants in POC1B cause nonsyndromic early childhood onset (first decade of life) slowly progressive cone rod dystrophy without night blindness, as well as syndromic retinal ciliopathy (Durlu et al. 2014. PubMed ID: 24945461; Beck et al. 2014. PubMed ID: 25044745). POC1B encodes a POC1 centriolar protein B, which is predominantly expressed in the ciliary region of photoreceptor cells and synapses of the outer plexiform layer (Beck et al. 2014. PubMed ID: 25044745). Depletion studies indicated that this protein is involved in ciliogenesis and is colocalized with another retinal-ciliopathy-associated protein FAM161A at the plasma membrane, basal body and is associated with the microtubule network photoreceptor homeostasis (Roosing et al. 2014. PubMed ID: 25018096). In vitro studies suggested that pathogenic POC1B variants in the WD40 domain of the protein strongly decreased its interaction with FAM161A, which might induce photoreceptor degeneration (Roosing et al. 2014. PubMed ID: 25018096). To date, ~5 pathogenic variants (missense, nonsense, splicing and small in-frame deletion) have been documented causative (Human Gene Mutation Database).

Clinical Sensitivity - Sequencing with CNV PGxome

Due to the genetic heterogeneity and limited number of reported cases, it is difficult to predict clinical sensitivity. Analytical sensitivity should be high as all reported pathogenic variants are detectable by sequencing.

Testing Strategy

This test provides full coverage of all coding exons of the POC1B 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 syndromic and nonsyndromic forms of Cone-rod dystrophy are candidates. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in POC1B.

Gene

Official Gene Symbol OMIM ID
POC1B 614784
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Disease

Name Inheritance OMIM ID
Cone-Rod Dystrophy 20 AR 615973

Related Test

Name
Cone-Rod Dystrophy Panel

Citations

  • Beck et al. 2014. PubMed ID: 25044745
  • Durlu et al. 2014. PubMed ID: 24945461
  • Hamel. 2007. PubMed ID: 17270046
  • Human Gene Mutation Database (Bio-base).
  • RetNet: Genes and Mapped Loci Causing Retinal Diseases
  • Roosing et al. 2014. PubMed ID: 25018096
  • Sung and Chuang. 2010. PubMed ID: 20855501

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)


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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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