X-Linked Complete Congenital Stationary Night Blindness (CSNB1) via the NYX 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
8705 NYX 81479 81479,81479 $890 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
8705NYX81479 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


Genetic Counselors


Clinical Features and Genetics

Clinical Features

X-linked congenital stationary night blindness (CSNB) is a non-progressive (stationary) inherited retinal disorder and has two clinical types, complete (CSNB1) and incomplete (CSNB2) (Rozzo et al. 1999). CSNB1 lacks rod function by electroretinography and dark adaptometry and refraction ranges from mild to severe myopia. CSNB2 shows some rod function on scotopic testing and refraction ranges from moderate hyperopia to moderate myopia (Musarella et al. 1989). Female carriers are usually asymptomatic (Musarella et al. 1989). However, a few cases of affected females in X-linked CSNB have been reported, most likely due to skewed X-inactivation (Ruttum et al. 1992).


Mutations in the NYX gene, which encodes glycosylphosphatidyl (GPI)-anchored protein called nyctalopin has been reported to be causative for CSNB1. Nyctalopin is a unique member of the leucine-rich proteoglycan family, which has shown to be expressed in both retina and kidney and may function as an adhesion molecule in the formation of synapses between neurons for the development of retinal interconnections (Bech-Hansen et al. 2000). So far, over 60 causative variants (missense, nonsense, splicing, small as well as gross deletions and duplications, complex genomic rearrangements) have been reported in this gene (Human Gene Mutation Database). A common NYX founder mutation c.855delG (p.Asp286Thrfs *62) has been reported in Flemish (population from Belgium) CSNB1 patients (Leroy et al. 2009).

Clinical Sensitivity - Sequencing with CNV PGxome

Mutation screening in a total of 39 patients with CSNB1 from 29 families, detected NYX, TRPM1, GRM6 and GPR179 mutations in ~50% (20 patients, 13 families), ~25% (10 patients, 9 families), ~10% (4 patients, 3 families), and ~5% (2 patients, 1 family) of the patients, respectively (Bijveld et al. 2013). In an additional report, NYX mutations are reported to be a common cause of CSNB1 (Wang 2012).

Testing Strategy

This test provides full coverage of all coding exons of the NYX 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 complete congenital stationary night blindness (CSNB1) are candidates.


Official Gene Symbol OMIM ID
NYX 300278
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT


Name Inheritance OMIM ID
Night Blindness, Congenital Stationary, Type 1A XL 310500



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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View Ordering Instructions

1) Select Test Type

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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