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Autosomal Dominant Vitelliform Macular Dystrophy via the IMPG1 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
IMPG1 81479 81479,81479 $990
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
10659IMPG181479 81479,81479 $990 Order Options and Pricing

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).

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

IMPG1-associated vitelliform macular dystrophies (VMD) are inherited retinal dystrophies characterized by macular or multifocal vitelliform (egg-yolk) deposits visible upon fundus examination in individuals with juvenile Best macular dystrophy (BMD) or adult-onset vitelliform macular dystrophy (AVMD) (Manes et al. 2013. PubMed ID: 23993198).


Macular dystrophies BMD and AVMD are heterogeneous. The majority of cases have pathogenic variants in BEST1 nad PRPH2 (Manes et al. 2013. PubMed ID: 23993198). 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).

Pathogenic variants in IMPG1 have been documented causative for autosomal dominant (AD) late-onset vitelliform macular dystrophy (Meunier et al. 2014. PubMed ID: 25085631). IMPG1 and another gene IMPG2 encode the interphotoreceptor matrix proteoglycan 1 and 2, 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, ~10 pathogenic variants (missense, nonsense and splicing) in IMPG1 have been connected to vitelliform macular dystrophies (Human Gene Mutation Database).

Clinical Sensitivity - Sequencing with CNV PGxome

Predicting clinical sensitivity for the IMPG1 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 IMPG1 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.


Official Gene Symbol OMIM ID
IMPG1 602870
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT


Name Inheritance OMIM ID
Macular Dystrophy, Vitelliform, 4 AD 616151

Related Tests

Autosomal Recessive Retinitis Pigmentosa 69 (RP69) via the IMPG2 Gene
Autosomal Recessive Retinitis Pigmentosa 77 (RP77) via the REEP6 Gene
Retinitis Pigmentosa Panel


  • Brandl et al. 2017. PubMed ID: 28644393
  • Human Gene Mutation Database (Bio-base).
  • Manes et al. 2013. PubMed ID: 23993198
  • Meunier et al. 2014. PubMed ID: 25085631


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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2) Select Additional Test Options

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Note: acceptable specimen types are whole blood and DNA from whole blood only.
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