Congenital Stationary Night Blindness and Retinal Degeneration via the SLC24A1 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
11671 SLC24A1 81479 81479,81479 $890 Order Options and Pricing
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
11671SLC24A181479 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

Congenital Stationary Night Blindness (CSNB) is a retinal condition with negative bright-flash dark-adapted electroretinogram response, and optic atrophy or dysplastic changes, or both, in the optic nerve head. Typical findings of CSNB include impaired night vision, no pigmentary retinopathy, full visual fields consistent with myopia and strabismus, which appear from early childhood and are nonprogressive (Heckenlively et al. 1983; Nakamura et al. 2001).Early stages of retinitis pigmentosa (RP) and CSNB are difficult to distinguish. RP and Leber Congenital Amaurosis (LCA) are inherited degenerative diseases of the retina. RP is characterized by night blindness, with age of onset varying from childhood to middle age, progression to constriction of the peripheral visual field and, eventually, to loss of central vision. LCA is characterized by bilateral congenital blindness. Several clinical features of LCA overlap with those of RP. These include attenuated retinal vessels, abnormal ERG findings and a variable amount of retinal pigmentation (Perrault et al. 1996; Daiger et al. 2007; Gu et al. 1999). Both LCA and RP are clinically and genetically heterogeneous.

Genetics

Maintenance of calcium and sodium concentrations within the rod and cone outer segments is essential for phototransduction, and is regulated by the two similar exchanger or solute carrier proteins in the rod and cones encoded by SLC24A1 and SLC24A2, respectively. Mutations in SLC24A1 are involved with autosomal recessive (AR) CSNB or retinal degeneration (Sharon et al. 2002; Riazuddin et al. 2010). A mutation analysis in a large multigeneration family found five CSNB affected individuals who were homozygous for a SLC24A1 small deletion (c.1613_1614del, p.Phe538Cysfs*23), which segregated with the disease and was not found in 384 control chromosomes (Riazuddin et al. 2010). Mouse studies have shown that SLC24A1 is predominantly expressed in the inner segment, outer and inner nuclear layers of the retina. It is also expressed at low levels in the cornea, lens, and optic nerve (Riazuddin et al. 2010). About twenty causative mutations have been reported in this rod exchanger gene in patients with retinal degeneration (Sharon et al. 2002; Human Gene Mutation Database).

Clinical Sensitivity - Sequencing with CNV PGxome

Predicting clinical sensitivity for the SLC24A1 gene is challenging due to genetic heterogeneity of optic atrophy. However, analytical sensitivity should be high because nearly all reported mutations are detectable by this method (Human Gene Mutation Database).

Testing Strategy

This test provides full coverage of all coding exons of the SLC24A1 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

Patients with symptoms suggestive of inherited optic neuropathy in CSNB or retinal degeneration are candidates. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in SLC24A1.

Gene

Official Gene Symbol OMIM ID
SLC24A1 603617
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT

Disease

Name Inheritance OMIM ID
Night Blindness, Congenital Stationary, Type 1D AR 613830

Citations

  • Daiger SP, Bowne SJ, Sullivan LS. 2007. Perspective on genes and mutations causing retinitis pigmentosa. Archives of ophthalmology 125: 151-158. PubMed ID: 17296890
  • Gu S. et al. 1999. Journal of Medical Genetics. 36: 705-7. PubMed ID: 10507729
  • Heckenlively JR, Martin DA, Rosenbaum AL. 1983. Loss of electroretinographic oscillatory potentials, optic atrophy, and dysplasia in congenital stationary night blindness. Am. J. Ophthalmol. 96: 526–534. PubMed ID: 6605090
  • Human Gene Mutation Database (Bio-base).
  • Nakamura M, Ito S, Terasaki H, Miyake Y. 2001. Novel CACNA1F mutations in Japanese patients with incomplete congenital stationary night blindness. Investigative ophthalmology & visual science 42: 1610–1616. PubMed ID: 11381068
  • Perrault I, Rozet JM, Calvas P, Gerber S, Camuzat A, Dollfus H, Châtelin S, Souied E, Ghazi I, Leowski C, Bonnemaison M, Paslier D Le, et al. 1996. Retinal-specific guanylate cyclase gene mutations in Leber’s congenital amaurosis. Nat. Genet. 14: 461–464. PubMed ID: 8944027
  • Riazuddin SA, Shahzadi A, Zeitz C, Ahmed ZM, Ayyagari R, Chavali VRM, Ponferrada VG, Audo I, Michiels C, Lancelot M-E, Nasir IA, Zafar AU, et al. 2010. A Mutation in SLC24A1 Implicated in Autosomal-Recessive Congenital Stationary Night Blindness. The American Journal of Human Genetics 87: 523–531. PubMed ID: 20850105
  • Sharon D, Yamamoto H, McGee TL, Rabe V, Szerencsei RT, Winkfein RJ, Prinsen CF, Barnes CS, Andreasson S, Fishman GA, others. 2002. Mutated alleles of the rod and cone Na-Ca+ K-exchanger genes in patients with retinal diseases. Investigative ophthalmology & visual science 43: 1971–1979. PubMed ID: 12037007

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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