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Autosomal Recessive Retinitis Pigmentosa 59 (RP59) via the DHDDS Gene

Summary and Pricing

Test Method

Sequencing and CNV Detection via NextGen Sequencing using PG-Select Capture Probes
Test Code Test Copy GenesTest CPT Code Gene CPT Codes Copy CPT Codes Base Price
7625 DHDDS 81479 81479,81479 $640 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
7625DHDDS81479 81479,81479 $640 Order Options and Pricing

Pricing Comments

This test is also offered via our exome backbone with CNV detection (click here). The exome-based test may be higher priced, but permits reflex to the entire exome or to any other set of clinically relevant genes.

An additional 25% charge will be applied to STAT orders. STAT orders are prioritized throughout the testing process.

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

Retinitis pigmentosa (RP) or rod cone dystrophies (RCDs) represent a group of hereditary retinal dystrophies with a worldwide prevalence of ~1 in 4,000 (Booij et al. 2005. PubMed ID: 16272259). RP is clinically characterized by retinal pigment deposits visible on fundus examination, nyctalopia ("night blindness"), followed by progressive degeneration of the photoreceptors, which eventually leads to blindness (van Soest et al. 1999. PubMed ID: 10025514).

Genetics

Nonsyndromic RP is remarkably heterogeneous both clinically and genetically and exhibits autosomal dominant (AD), autosomal recessive (AR) or X-linked (XL) inheritance. To date, over 50 loci have been linked to nonsyndromic RP, and 18, 27 and 2 genes have been identified that are involved with AD, AR and XL forms, respectively (RetNet).

Bi-allelic pathogenic variants in DHDDS are associated with retinitis pigmentosa especially in Ashkenazi Jews (Zelinger et al. 2011. PubMed ID: 21295282; Lam et al. 2014. PubMed ID: 24664694). DHDDS encodes dehydrodolichyl diphosphate synthase, which is primarily expressed in photoreceptor inner segments. This is a key enzyme in the pathway of dolichol biosynthesis, which plays an important role in N-glycosylation of many glycoproteins, including rhodopsin, and plays an essential role in retinal function (Zelinger et al. 2011. PubMed ID: 21295282). So far, less than 5 pathogenic variants (only missense variants) have been associated with DHDDS-associated RP and (Human Gene Mutation Database).

To date, two out of three missense DHDDS pathogenic variants reported were found in the Ashkenazi Jewish (AJ) RP population (Züchner et al. 2011. PubMed ID: 21295283; Zelinger et al. 2011. PubMed ID: 21295282). The p.Lys42Glu variant was reported in 12% (15/123) of the AJ RP patients and reported as a founder mutation (Zelinger et al. 2011. PubMed ID: 21295282). RP patients with AJ ancestry should consider for the screening of p.Lys42Glu variant first (Zelinger et al. 2011. PubMed ID: 21295282).

Of note, pathogenic variants in this genes have also been documented causative for Developmental and epileptic encephalopathy and a Congenital disorder of glycosylation (Human Gene Mutation Database).

Clinical Sensitivity - Sequencing with CNV PG-Select

DHDDS is associated with retinitis pigmentosa in Ashkenazi Jews (over 10% of AJ RP patients) (Zelinger et al. 2011. PubMed ID: 21295282; Lam et al. 2014. PubMed ID: 24664694). RP patients with AJ ancestry should consider screening for the p.Lys42Glu variant first (Zelinger et al. 2011. PubMed ID: 21295282).

Testing Strategy

This test provides full coverage of all coding exons of the DHDDS gene, plus ~10 bases of flanking noncoding DNA. We define full coverage as >20X NGS reads or Sanger sequencing.

Indications for Test

All patients with symptoms suggestive of AR RP especially patients with bull's eye maculopathy, and relatives of patients with known DHDDS pathogenic variants. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in DHDDS.

Gene

Official Gene Symbol OMIM ID
DHDDS 608172
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Disease

Name Inheritance OMIM ID
Retinitis Pigmentosa 59 AR 613861

Related Tests

Name
Autosomal Recessive Retinitis Pigmentosa 26 (RP26) via the CERKL Gene
Autosomal Recessive Retinitis Pigmentosa 36 (RP36) via the PRCD Gene
Retinitis Pigmentosa (includes RPGR ORF15) Panel

Citations

  • Booij et al. 2005. PubMed ID: 16272259
  • Human Gene Mutation Database (Bio-base).
  • Lam et al. 2014. PubMed ID: 24664694
  • RetNet: Genes and Mapped Loci Causing Retinal Diseases.
  • van Soest et al. 1999. PubMed ID: 10025514
  • Zelinger et al. 2011. PubMed ID: 21295282
  • Züchner et al. 2011. PubMed ID: 21295283

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

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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.
Total Price: $
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