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CNGB3 gene
URL of this page: https://medlineplus.gov/genetics/gene/cngb3/

CNGB3 gene

cyclic nucleotide gated channel subunit beta 3

Normal Function

The CNGB3 gene provides instructions for making one part (the beta subunit) of the cyclic nucleotide-gated (CNG) channel. These channels are found exclusively in light-sensing (photoreceptor) cells called cones, which are located in a specialized tissue at the back of the eye (retina). Cones provide color vision and vision in bright light (daytime vision). Other photoreceptor cells, called rods, provide vision in low light (night vision).

CNG channels are openings in the cell membrane that transport positively charged atoms (ions) into cells. The CNG channels in cones remain open in low light, allowing ions to flow in. When light enters the eye, these channels close, stopping the flow of ions. This change in ion transport alters the cone's electrical charge, which ultimately generates a signal. This signal is sent to the brain, where it combines with other visual information and is interpreted as vision. The process of translating light into an electrical signal is called phototransduction.

Health Conditions Related to Genetic Changes

Achromatopsia

Variants (also called mutations) in the CNGB3 gene can cause achromatopsia. Achromatopsia is a disorder of the retina. Some people with achromatopsia cannot perceive any color; they see only black, white, and shades of gray. Other affected individuals can see some color. Approximately 40 to 50 percent of people with achromatopsia have a variant in the CNGB3 gene. Variants in the CNGB3 gene are more common in affected individuals from Europe and the United States.  

Complete achromatopsia, which is the form of the disorder that results in total loss of color vision, occurs more frequently among Pingelapese islanders, who live in parts of Micronesia in the western Pacific Ocean. Among this population, the condition is typically caused by a particular variant that results in the substitution of one protein building block (amino acid) for another in the beta subunit. In this case, the amino acid serine is replaced with the amino acid phenylalanine at position 435 (written as Ser435Phe).

Most of the CNGB3 gene variants that cause achromatopsia cause cells to produce a version of the protein that does not function properly. The altered beta subunits impair the function of the CNG channels, which impairs the cones' ability to respond to light. This causes the lack of color vision and contributes to the other vision problems found in people with achromatopsia.

More About This Health Condition

Cone-rod dystrophy

MedlinePlus Genetics provides information about Cone-rod dystrophy

More About This Health Condition

Other disorders

Variants in the CNGB3 gene have also been found in some people with progressive cone dystrophy. Like achromatopsia, this condition affects the function of cones. However, individuals with progressive cone dystrophy begin having problems with cone function in childhood or adolescence. Progressive cone dystrophy causes vision problems, such as an increased sensitivity to light and a reduced ability to see color, that worsen over time. It is unclear why some CNGB3 gene variants cause achromatopsia, while others result in progressive cone dystrophy.

Other Names for This Gene

  • ACHM3
  • achromatopsia (rod monochromacy) 3
  • cyclic nucleotide gated channel beta 3

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

Scientific Articles on PubMed

Catalog of Genes and Diseases from OMIM

Gene and Variant Databases

References

  • Hirji N, Aboshiha J, Georgiou M, Bainbridge J, Michaelides M. Achromatopsia: clinical features, molecular genetics, animal models and therapeutic options. Ophthalmic Genet. 2018 Apr;39(2):149-157. doi: 10.1080/13816810.2017.1418389. Epub 2018 Jan 5. Citation on PubMed
  • Johnson S, Michaelides M, Aligianis IA, Ainsworth JR, Mollon JD, Maher ER, Moore AT, Hunt DM. Achromatopsia caused by novel mutations in both CNGA3 and CNGB3. J Med Genet. 2004 Feb;41(2):e20. doi: 10.1136/jmg.2003.011437. No abstract available. Citation on PubMed or Free article on PubMed Central
  • Kohl S, Baumann B, Broghammer M, Jagle H, Sieving P, Kellner U, Spegal R, Anastasi M, Zrenner E, Sharpe LT, Wissinger B. Mutations in the CNGB3 gene encoding the beta-subunit of the cone photoreceptor cGMP-gated channel are responsible for achromatopsia (ACHM3) linked to chromosome 8q21. Hum Mol Genet. 2000 Sep 1;9(14):2107-16. doi: 10.1093/hmg/9.14.2107. Citation on PubMed
  • Kohl S, Jagle H, Wissinger B, Zobor D. Achromatopsia. 2004 Jun 24 [updated 2018 Sep 20]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews(R) [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2025. Available from http://www.ncbi.nlm.nih.gov/books/NBK1418/ Citation on PubMed
  • Kohl S, Varsanyi B, Antunes GA, Baumann B, Hoyng CB, Jagle H, Rosenberg T, Kellner U, Lorenz B, Salati R, Jurklies B, Farkas A, Andreasson S, Weleber RG, Jacobson SG, Rudolph G, Castellan C, Dollfus H, Legius E, Anastasi M, Bitoun P, Lev D, Sieving PA, Munier FL, Zrenner E, Sharpe LT, Cremers FP, Wissinger B. CNGB3 mutations account for 50% of all cases with autosomal recessive achromatopsia. Eur J Hum Genet. 2005 Mar;13(3):302-8. doi: 10.1038/sj.ejhg.5201269. Citation on PubMed
  • Michaelides M, Aligianis IA, Ainsworth JR, Good P, Mollon JD, Maher ER, Moore AT, Hunt DM. Progressive cone dystrophy associated with mutation in CNGB3. Invest Ophthalmol Vis Sci. 2004 Jun;45(6):1975-82. doi: 10.1167/iovs.03-0898. Citation on PubMed
  • Michalakis S, Gerhardt M, Rudolph G, Priglinger S, Priglinger C. Achromatopsia: Genetics and Gene Therapy. Mol Diagn Ther. 2022 Jan;26(1):51-59. doi: 10.1007/s40291-021-00565-z. Epub 2021 Dec 3. Citation on PubMed
  • Sundin OH, Yang JM, Li Y, Zhu D, Hurd JN, Mitchell TN, Silva ED, Maumenee IH. Genetic basis of total colourblindness among the Pingelapese islanders. Nat Genet. 2000 Jul;25(3):289-93. doi: 10.1038/77162. Citation on PubMed
  • Thiadens AA, Roosing S, Collin RW, van Moll-Ramirez N, van Lith-Verhoeven JJ, van Schooneveld MJ, den Hollander AI, van den Born LI, Hoyng CB, Cremers FP, Klaver CC. Comprehensive analysis of the achromatopsia genes CNGA3 and CNGB3 in progressive cone dystrophy. Ophthalmology. 2010 Apr;117(4):825-30.e1. doi: 10.1016/j.ophtha.2009.09.008. Epub 2010 Jan 15. Citation on PubMed
  • Wiszniewski W, Lewis RA, Lupski JR. Achromatopsia: the CNGB3 p.T383fsX mutation results from a founder effect and is responsible for the visual phenotype in the original report of uniparental disomy 14. Hum Genet. 2007 May;121(3-4):433-9. doi: 10.1007/s00439-006-0314-y. Epub 2007 Jan 31. Citation on PubMed

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