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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


Reviewed May 2009

What is the official name of the NYX gene?

The official name of this gene is “nyctalopin.”

NYX is the gene's official symbol. The NYX gene is also known by other names, listed below.

What is the normal function of the NYX gene?

The NYX gene provides instructions for making a protein called nyctalopin, which plays an important role in a specialized tissue at the back of the eye called the retina. Within the retina, nyctalopin is located on the surface of light-detecting cells called photoreceptors. The retina contains two types of photoreceptors: rods and cones. Rods are responsible for vision in low light. Cones provide vision in bright light, including color vision.

Nyctalopin appears to play a critical role in normal vision. Studies suggest the protein helps relay visual signals from rods and cones to other retinal cells called bipolar cells. This signaling is an essential step in the transmission of visual information from the eyes to the brain.

How are changes in the NYX gene related to health conditions?

X-linked congenital stationary night blindness - caused by mutations in the NYX gene

More than 50 mutations in the NYX gene have been identified in people with X-linked congenital stationary night blindness. Mutations in this gene are responsible for the complete form of the disorder, which is characterized by difficulty seeing in low light (night blindness), loss of sharpness (reduced acuity), severe nearsightedness (high myopia), involuntary movements of the eyes (nystagmus), and eyes that do not look in the same direction (strabismus).

Many NYX mutations change single protein building blocks (amino acids) in nyctalopin. NYX mutations can change the size or shape of the protein or prevent it from attaching to the surface of photoreceptor cells. A loss of functional nyctalopin disrupts the ability of photoreceptor cells to transmit visual signals, which impairs vision. The function of rods is severely disrupted, while the function of cones is only mildly affected.

other disorders - caused by mutations in the NYX gene

At least two mutations in the NYX gene have been found to cause high myopia without the other vision problems characteristic of X-linked congenital stationary night blindness. The mutations responsible for high myopia each change a single amino acid in nyctalopin, which is predicted to result in an unstable protein. Researchers are uncertain why these mutations cause high myopia without any other vision abnormalities.

Where is the NYX gene located?

Cytogenetic Location: Xp11.4

Molecular Location on the X chromosome: base pairs 41,445,637 to 41,476,421

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBI (

The NYX gene is located on the short (p) arm of the X chromosome at position 11.4.

The NYX gene is located on the short (p) arm of the X chromosome at position 11.4.

More precisely, the NYX gene is located from base pair 41,445,637 to base pair 41,476,421 on the X chromosome.

See How do geneticists indicate the location of a gene? ( in the Handbook.

Where can I find additional information about NYX?

You and your healthcare professional may find the following resources about NYX helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the NYX gene or gene products?

  • CLRP
  • CSNB1
  • CSNB1A
  • CSNB4
  • leucine-rich repeat protein
  • MGC138447

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding NYX?

acids ; amino acid ; cones ; congenital ; gene ; involuntary ; leucine ; myopia ; nearsightedness ; nystagmus ; photoreceptor ; protein ; retina ; rods ; strabismus ; synapse ; tissue

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Bech-Hansen NT, Naylor MJ, Maybaum TA, Sparkes RL, Koop B, Birch DG, Bergen AA, Prinsen CF, Polomeno RC, Gal A, Drack AV, Musarella MA, Jacobson SG, Young RS, Weleber RG. Mutations in NYX, encoding the leucine-rich proteoglycan nyctalopin, cause X-linked complete congenital stationary night blindness. Nat Genet. 2000 Nov;26(3):319-23. (
  • Jacobi FK, Andréasson S, Langrova H, Meindl A, Zrenner E, Apfelstedt-Sylla E, Pusch CM. Phenotypic expression of the complete type of X-linked congenital stationary night blindness in patients with different mutations in the NYX gene. Graefes Arch Clin Exp Ophthalmol. 2002 Oct;240(10):822-8. Epub 2002 Sep 21. (
  • Leroy BP, Budde BS, Wittmer M, De Baere E, Berger W, Zeitz C. A common NYX mutation in Flemish patients with X linked CSNB. Br J Ophthalmol. 2009 May;93(5):692-6. doi: 10.1136/bjo.2008.143727. Epub 2008 Jul 10. (
  • Morgans CW, Ren G, Akileswaran L. Localization of nyctalopin in the mammalian retina. Eur J Neurosci. 2006 Mar;23(5):1163-71. (
  • NCBI Gene (
  • O'Connor E, Eisenhaber B, Dalley J, Wang T, Missen C, Bulleid N, Bishop PN, Trump D. Species specific membrane anchoring of nyctalopin, a small leucine-rich repeat protein. Hum Mol Genet. 2005 Jul 1;14(13):1877-87. Epub 2005 May 19. (
  • Poopalasundaram S, Erskine L, Cheetham ME, Hardcastle AJ. Focus on molecules: nyctalopin. Exp Eye Res. 2005 Dec;81(6):627-8. Epub 2005 Sep 12. Review. (
  • Pusch CM, Zeitz C, Brandau O, Pesch K, Achatz H, Feil S, Scharfe C, Maurer J, Jacobi FK, Pinckers A, Andreasson S, Hardcastle A, Wissinger B, Berger W, Meindl A. The complete form of X-linked congenital stationary night blindness is caused by mutations in a gene encoding a leucine-rich repeat protein. Nat Genet. 2000 Nov;26(3):324-7. (
  • Xiao X, Jia X, Guo X, Li S, Yang Z, Zhang Q. CSNB1 in Chinese families associated with novel mutations in NYX. J Hum Genet. 2006;51(7):634-40. Epub 2006 May 3. (
  • Zeitz C, Scherthan H, Freier S, Feil S, Suckow V, Schweiger S, Berger W. NYX (nyctalopin on chromosome X), the gene mutated in congenital stationary night blindness, encodes a cell surface protein. Invest Ophthalmol Vis Sci. 2003 Oct;44(10):4184-91. (
  • Zhang Q, Xiao X, Li S, Jia X, Yang Z, Huang S, Caruso RC, Guan T, Sergeev Y, Guo X, Hejtmancik JF. Mutations in NYX of individuals with high myopia, but without night blindness. Mol Vis. 2007 Mar 1;13:330-6. (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: May 2009
Published: February 8, 2016