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Autosomal Recessive Retinitis Pigmentosa 69 (RP69) via the IMPG2 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
IMPG2 81479 81479,81479 $990
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
10643IMPG281479 81479,81479 $990 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.

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).

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

For Sanger Sequencing click here.

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.


Genetic Counselors


  • Dana Talsness, PhD

Clinical Features and Genetics

Clinical Features

Retinitis pigmentosa (RP) represents 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).


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 associated with AD, AR, and XL RP, respectively (RetNet).

Pathogenic variants in IMPG2 have been documented causative for autosomal recessive (AR) Retinitis Pigmentosa (RP) with relatively early macular involvement (Bandah-Rozenfeld et al. 2010. PubMed ID: 20673862; van Huet et al. 2014. PubMed ID: 24876279) and autosomal dominant (AD) late-onset vitelliform macular dystrophy (Meunier et al. 2014. PubMed ID: 25085631).

IMPG2 and another gene IMPG1 encode the interphotoreceptor matrix proteoglycan 2 and 1, respectively. IMPG1 and IMPG2 are also known as sialoprotein associated with cones and rods (SPACR) and SPACRCAN (a proteoglyCan related to SPACR), respectively. These are large glycosylated protein components of the insoluble interphotoreceptor matrix (IPM). Both these proteins consist of hyaluronan (HA) binding motifs and it is believed that they bind to HA and that their interaction stabilizes or modulates the IPM scaffold (Brandl et al. 2017. PubMed ID: 28644393). To date, over 30 pathogenic variants (missense, nonsense, splicing, small frameshift deletions, insertions and a large deletion) in IMPG2 have been connected to retinal disorders (Human Gene Mutation Database). Of note, loss of function variants repeatedly have been reported in cases with AR inheritance (Brandl et al. 2017. PubMed ID: 28644393).

Clinical Sensitivity - Sequencing with CNV PGxome

Predicting clinical sensitivity for the IMPG2 gene is challenging due to genetic heterogeneity. However, IMPG1 and IMPG2 are new causal genes in 8% of cases that are negative for BEST1 and PRPH2 causative variants (Meunier et al. 2014. PubMed ID: 25085631).

Testing Strategy

This test provides full coverage of all coding exons of the IMPG2 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 retinal disorders are candidates. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in IMPG2.


Official Gene Symbol OMIM ID
IMPG2 607056
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Related Tests

Autosomal Recessive Retinitis Pigmentosa 77 (RP77) via the REEP6 Gene
Retinitis Pigmentosa Panel


  • Bandah-Rozenfeld et al. 2010. PubMed ID: 20673862
  • Booij et al. 2005. PubMed ID: 16272259
  • Brandl et al. 2017. PubMed ID: 28644393
  • Human Gene Mutation Database (Bio-base).
  • Meunier et al. 2014. PubMed ID: 25085631
  • RetNet: Genes and Mapped Loci Causing Retinal Diseases.
  • van Huet et al. 2014. PubMed ID: 24876279
  • van Soest et al. 1999. PubMed ID: 10025514


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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View Ordering Instructions

1) Select Test Method (Platform)

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2) Select Additional Test Options

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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