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 Genes | Test CPT Code | Gene CPT Codes Copy CPT Code | Base Price | |
|---|---|---|---|---|---|
| 7625 | DHDDS | 81479 | 81479,81479 | $990 | Order Options and Pricing |
Pricing Comments
Testing run on PG-select capture probes includes CNV analysis for the gene(s) on the panel but does not permit the optional add on of exome-wide CNV analysis. Any of the NGS platforms allow reflex to other clinically relevant genes, up to whole exome or whole genome sequencing depending upon the base platform selected for the initial test.
An additional 25% charge will be applied to STAT orders. STAT orders are prioritized throughout the testing process.
This test is also offered via a custom panel (click here) on our exome or genome backbone which permits the optional add on of exome-wide CNV or genome-wide SV analysis.
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
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.
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 Panel |
Citations
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
Loading...
×
ORDER OPTIONS
View Ordering Instructions1) Select Test Type
2) Select Additional Test Options
No Additional Test Options are available for this test.