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RPE65 gene

retinoid isomerohydrolase RPE65

Normal Function

The RPE65 gene provides instructions for making a protein that is essential for normal vision. The RPE65 protein is produced in a thin layer of cells at the back of the eye called the retinal pigment epithelium (RPE). This cell layer supports and nourishes the retina, which is the light-sensitive tissue that lines the back of the eye. The RPE layer is essential for capturing light and vision.

The RPE65 protein is involved in a multi-step process called the visual cycle (also called the retinoid or vitamin A cycle), which converts light entering the eye into electrical signals that are transmitted to the brain. When light hits photosensitive pigments in the retina, it changes a molecule called 11-cis retinal (a form of vitamin A) to another molecule called all-trans retinal. This conversion triggers a series of chemical reactions that create electrical signals. 

The RPE65 protein  is a key enzyme in this cycle as it converts all-trans retinal to 11-cis retinol. Other enzymes then produce 11-cis retinal, so that the visual cycle can begin again and capture light.

Health Conditions Related to Genetic Changes

Leber congenital amaurosis

Many variants (also called mutations) in the RPE65 gene have been found to cause Leber congenital amaurosis. This condition is an eye disorder that primarily affects the retina. People with this disorder typically have severe visual impairment beginning at birth or shortly afterward. Variants in the RPE65 gene account for 6 to 16 percent of all cases of this condition. 

RPE65 gene variants lead to a partial or total loss of RPE65 protein function. As a result, all-trans retinal cannot be converted back to 11-cis retinal, and excess all-trans retinal builds up in the retinal pigment epithelium. These abnormalities block the visual cycle, which leads to severe visual impairment beginning very early in life in Leber congenital amaurosis.

More About This Health Condition

Fundus albipunctatus

MedlinePlus Genetics provides information about Fundus albipunctatus

More About This Health Condition

Retinitis pigmentosa

MedlinePlus Genetics provides information about Retinitis pigmentosa

More About This Health Condition

Other Names for This Gene

  • all-trans-retinyl-palmitate hydrolase
  • BCO3
  • LCA2
  • mRPE65
  • p63
  • RBP-binding membrane protein
  • rd12
  • retinal pigment epithelium specific protein 65
  • retinal pigment epithelium-specific 65 kDa protein
  • retinal pigment epithelium-specific protein 65kDa
  • retinitis pigmentosa 20 (autosomal recessive)
  • retinoid isomerohydrolase
  • retinol isomerase
  • RP20
  • sRPE65

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


  • Cai X, Conley SM, Naash MI. RPE65: role in the visual cycle, human retinal disease, and gene therapy. Ophthalmic Genet. 2009 Jun;30(2):57-62. doi: 10.1080/13816810802626399. Citation on PubMed or Free article on PubMed Central
  • Cideciyan AV, Aleman TS, Boye SL, Schwartz SB, Kaushal S, Roman AJ, Pang JJ, Sumaroka A, Windsor EA, Wilson JM, Flotte TR, Fishman GA, Heon E, Stone EM, Byrne BJ, Jacobson SG, Hauswirth WW. Human gene therapy for RPE65 isomerase deficiency activates the retinoid cycle of vision but with slow rod kinetics. Proc Natl Acad Sci U S A. 2008 Sep 30;105(39):15112-7. doi: 10.1073/pnas.0807027105. Epub 2008 Sep 22. Citation on PubMed or Free article on PubMed Central
  • den Hollander AI, Roepman R, Koenekoop RK, Cremers FP. Leber congenital amaurosis: genes, proteins and disease mechanisms. Prog Retin Eye Res. 2008 Jul;27(4):391-419. doi: 10.1016/j.preteyeres.2008.05.003. Epub 2008 Jun 1. Citation on PubMed
  • Morimura H, Fishman GA, Grover SA, Fulton AB, Berson EL, Dryja TP. Mutations in the RPE65 gene in patients with autosomal recessive retinitis pigmentosa or leber congenital amaurosis. Proc Natl Acad Sci U S A. 1998 Mar 17;95(6):3088-93. doi: 10.1073/pnas.95.6.3088. Citation on PubMed or Free article on PubMed Central
  • Redmond TM, Poliakov E, Yu S, Tsai JY, Lu Z, Gentleman S. Mutation of key residues of RPE65 abolishes its enzymatic role as isomerohydrolase in the visual cycle. Proc Natl Acad Sci U S A. 2005 Sep 20;102(38):13658-63. doi: 10.1073/pnas.0504167102. Epub 2005 Sep 6. Citation on PubMed or Free article on PubMed Central
  • Redmond TM. Focus on Molecules: RPE65, the visual cycle retinol isomerase. Exp Eye Res. 2009 May;88(5):846-7. doi: 10.1016/j.exer.2008.07.015. Epub 2008 Aug 14. No abstract available. Citation on PubMed or Free article on PubMed Central
  • Thompson DA, Gyurus P, Fleischer LL, Bingham EL, McHenry CL, Apfelstedt-Sylla E, Zrenner E, Lorenz B, Richards JE, Jacobson SG, Sieving PA, Gal A. Genetics and phenotypes of RPE65 mutations in inherited retinal degeneration. Invest Ophthalmol Vis Sci. 2000 Dec;41(13):4293-9. Citation on PubMed
  • Travis GH, Golczak M, Moise AR, Palczewski K. Diseases caused by defects in the visual cycle: retinoids as potential therapeutic agents. Annu Rev Pharmacol Toxicol. 2007;47:469-512. doi: 10.1146/annurev.pharmtox.47.120505.105225. Citation on PubMed or Free article on PubMed Central

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.