X-linked Retinitis Pigmentosa (XLRP) via the RP2 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
8821 RP2 81479 81479,81479 $890 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
8821RP281479 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.

A 25% additional charge will be applied to STAT orders. View STAT turnaround times here.

For Reflex to PGxome pricing click here.

The Sanger Sequencing method for this test is NY State approved.

For Sanger Sequencing click here.

Targeted Testing

For ordering sequencing of targeted known variants, go to our Targeted Variants page.

Turnaround Time

18 days on average

EMAIL CONTACTS

Genetic Counselors

Geneticist

Clinical Features and Genetics

Clinical Features

Retinitis pigmentosa (RP) refers to a group of related eye disorders stemming from the degeneration of photoreceptor cells in the retina (Pagon and Daiger, 2005). RP derives its name from retinal pigmentation changes. In RP patients, pigment granules accumulate in perivascular clusters, called bone spicules, in the retinal pigment epithelium (RPE). The accumulation of pigment is typically accompanied by death of the photoreceptor cells, first rods and eventually cones. As a result, RP will often present first with night blindness and decreased peripheral vision due to systematic loss of rod cells, followed by deterioration of central vision acuity and day blindness from the loss of cone cells. RP has an incidence of ~1/3500 and can be inherited in autosomal recessive, autosomal dominant, X-linked, digenic and even mitochondrial patterns. Currently, variants in over 30 genes are known to cause RP.

Genetics

X-linked RP (XLRP) is one of the most severe forms of RP, with early onset and rapid progression in males. Milder symptoms can also present in females, probably due to random X inactivation. At least five different genetic loci have been associated with XLRP: Xp11.2 (RP2), Xp21.1 (RPGR), Xp21.2-21.3 (RP6), Xp22 (RP23), and Xp26-27 (RP24) (http://www.sph.uth.tmc.edu/RetNet/disease.htm). To date, only the RP2 and RPGR genes have been identified. RPGR encodes the retinitis pigmentosa GTPase regulator (Meindl et al. Nat Genet 13:35-42, 1996), and RP2 encodes a protein of unknown function (Schwahn et al. 1998). Variants in RPGR account for the vast majority (~80%) of all XLRP cases while RP2 accounts for about 10% of cases and the other loci likely account for the remainder (~10%) (Breuer et al. 2002; Sharon et al. 2003). The RP2 gene consists of 5 exons with variants found throughout all five exons; no founder variants or mutational hotspots have been reported. Most variants result in premature protein termination (i.e. frameshift, nonsense, and splice-site), although a few missense variants have also been identified (Mears et al. 1999; Hardcastle et al. 1999). Males hemizygous for variants in RP2 typically display classic features of RP, such as initial night blindness and loss of peripheral vision. Patients with variants in RP2 appear to retain less visual acuity than patients with variants in RPGR (Sharon et al. 2003). Thus, knowledge of which XLRP gene is mutated is useful for making the most accurate long-term visual prognosis.

Clinical Sensitivity - Sequencing with CNV PGxome

This test is predicted to detect a causative variant in ~10-20% of all patients with presumptive XLRP (Breuer et al. Am J Hum Genet 70:1545-1554, 2002; Sharon et al. Am J Hum Genet 73:1131-1146, 2003).

Testing Strategy

This test provides full coverage of all coding exons of the RP2 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

This test is for patients with X-linked recessive retinitis pigmentosa (XLRP).

Gene

Official Gene Symbol OMIM ID
RP2 300757
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Disease

Name Inheritance OMIM ID
Retinitis Pigmentosa 2 XL 312600

Related Tests

Name
Primary Ciliary Dyskinesia (PCD) via the RPGR Gene
Retinitis Pigmentosa (includes RPGR ORF15) Panel
X-linked Retinitis Pigmentosa (XLRP) via the RPGR (includes ORF15) Gene

Citations

  • Breuer DK, Yashar BM, Filippova E, Hiriyanna S, Lyons RH, Mears AJ, Asaye B, Acar C, Vervoort R, Wright AF. 2002. A Comprehensive Mutation Analysis of RP2 and RPGR in a North American Cohort of Families with X-Linked Retinitis Pigmentosa. The American Journal of Human Genetics 70: 1545–1554. PubMed ID: 11992260
  • Fahim AT. et al. 2013. Retinitis Pigmentosa Overview. 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: 20301590
  • Hardcastle AJ, Thiselton DL, Maldergem L Van, Saha BK, Jay M, Plant C, Taylor R, Bird AC, Bhattacharya S. 1999. Mutations in the RP2 gene cause disease in 10% of families with familial X-linked retinitis pigmentosa assessed in this study. American journal of human genetics 64: 1210. PubMed ID: 10090907
  • Mears AJ, Gieser L, Yan D, Chen C, Fahrner S, Hiriyanna S, Fujita R, Jacobson SG, Sieving PA, Swaroop A. 1999. Protein-truncation mutations in the RP2 gene in a North American cohort of families with X-linked retinitis pigmentosa. Am. J. Hum. Genet. 64: 897–900. PubMed ID: 10053026
  • RetNet: Genes and Mapped Loci Causing Retinal Diseases
  • Schwahn, U., et.al. (1998). "Positional cloning of the gene for X-linked retinitis pigmentosa 2." Nat Genet 19(4): 327-32. PubMed ID: 9697692
  • Sharon D, Sandberg MA, Rabe VW, Stillberger M, Dryja TP, Berson EL. 2003. RP2 and RPGR Mutations and Clinical Correlations in Patients with X-Linked Retinitis Pigmentosa. The American Journal of Human Genetics 73: 1131–1146. PubMed ID: 14564670

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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