Fundus Albipunctatus With or Without Cone Dystrophy via the RDH5 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
4223 RDH5 81479 81479,81479 $890 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
4223RDH581479 81479 $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. 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.

For Reflex to PGxome pricing click here.

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 14 days on average for STAT orders.

Once a specimen has started the testing process in our lab, the most accurate prediction of TAT will be displayed in the myPrevent portal as an Estimated Report Date (ERD) range. We calculate the ERD for each specimen as testing progresses; therefore the ERD range may differ from our published average TAT. View 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

Clinical Features and Genetics

Clinical Features

Fundus albipunctatus (FA) is a relatively mild and rare form of congenital stationary night blindness (CSNB). FA is characterized by poor night vision with prolonged dark adaptation and the presence of a large number of discrete, small round or elliptical yellow-white lesions in the perimacular area and retinal periphery (Nakamura et al. 2000). Approximately 38% of FA patients have been reported to have extensive cone dysfunction (Niwa 2005).

Genetics

Fundus albipunctatus is inherited in an autosomal recessive manner. The causative gene, RDH5, located on chromosome 12q13-q14, encodes an enzyme called retinol dehydrogenase 5. RDH5 is predominantly expressed in retinal pigment epithelium (RPE) and is responsible for the oxidation of 11-cis retinol to the visual chromophore 11-cis-retinaldehyde (11-cis-RAL). The 11-cis-RAL is further transported to the photoreceptors for integration into opsins, making them amenable for photoactivation (Parker and Crouch 2010). Due to mutations in RDH5, which leads to visual chromophore deficiency, patients have characteristic white retinal spots named fundus albipunctatus (FA), which has been regarded as a mild retinal disorder that does not significantly affect central vision (Pras et al. 2012). Over forty mutations in RDH5 have been reported to be involved with autosomal recessive FA either with or without the development of cone dystrophy, especially in elderly patients (over 40 years old) (Liden 2001; Nakamura et al. 2000). The RDH5 mutation c.103G>A (p.G35S) is reported to be causative for FA with cone dystrophy (Wada et al. 2001). So far no gross deletions or duplications have been reported in RDH5 (Human Gene Mutation Database).

Clinical Sensitivity - Sequencing with CNV PGxome

RDH5 mutation screening identified heterozygous mutations in ~ 89% (34/38) of carrier chromosomes and ~84% (16/19) of FA patients had homozygous mutations (Pras et al. 2012). Another study showed that 9 patients from 8 families (aged 7-55 years) with night blindness and electrophysiologic or fundoscopic findings had RDH5 mutations (Sergouniotis et al. 2011).

Testing Strategy

This test provides full coverage of all coding exons of the RDH5 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.

Since this test is performed using exome capture probes, a reflex to any of our exome based tests is available (PGxome, PGxome Custom Panels).

Indications for Test

All patients with symptoms suggestive of Fundus albipunctatus with or without cone dystrophy, especially patients with characteristic appearance of a large number of discrete, small round or elliptical yellow-white lesions at the level of the RPE. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in RDH5.

Gene

Official Gene Symbol OMIM ID
RDH5 601617
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Disease

Name Inheritance OMIM ID
Pigmentary Retinal Dystrophy AR, AD 136880

Related Tests

Name
RHO-Related Disorders via the RHO Gene
RLBP1-Related Disorders via the RLBP1 Gene
Cone-Rod Dystrophy Panel
Flecked Retina Disorder Panel
Retinitis Pigmentosa (includes RPGR ORF15) Panel
Retinitis Pigmentosa via the PRPH2 (RDS) Gene

Citations

  • Human Gene Mutation Database (Bio-base).
  • Liden M. 2001. Biochemical Defects in 11-cis-Retinol Dehydrogenase Mutants Associated with Fundus Albipunctatus. Journal of Biological Chemistry 276: 49251–49257. PubMed ID: 11675386
  • Nakamura M, Hotta Y, Tanikawa A, Terasaki H, Miyake Y. 2000. A high association with cone dystrophy in Fundus albipunctatus caused by mutations of the RDH5 gene. Invest. Ophthalmol. Vis. Sci. 41: 3925–3932. PubMed ID: 11053295
  • Niwa Y, Kondo M, Ueno S, Nakamura M, Terasaki H, Miyake Y. 2005. Cone and rod dysfunction in fundus albipunctatus with RDH5 mutation: an electrophysiological study. Invest. Ophthalmol. Vis. Sci. 46: 1480–1485. PubMed ID: 15790919
  • Parker RO, Crouch RK. 2010. Retinol dehydrogenases (RDHs) in the visual cycle. Experimental Eye Research 91: 788–792. PubMed ID: 20801113
  • Pras E, Pras E, Reznik-Wolf H, Sharon D, Raivech S, Barkana Y, Abu-Horowitz A, Ygal R, Banin E. 2012. Fundus albipunctatus: novel mutations and phenotypic description of Israeli patients. Molecular vision 18: 1712. PubMed ID: 22815624
  • Sergouniotis PI, Sohn EH, Li Z, McBain VA, Wright GA, Moore AT, Robson AG, Holder GE, Webster AR. 2011. Phenotypic variability in RDH5 retinopathy (Fundus Albipunctatus). Ophthalmology 118: 1661–1670. PubMed ID: 21529959
  • Wada Y, Abe T, Sato H, Tamai M. 2001. A novel Gly35Ser mutation in the RDH5 gene in a Japanese family with fundus albipunctatus associated with cone dystrophy. Arch. Ophthalmol. 119: 1059–1063. PubMed ID: 11448328

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.

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

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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.

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