RPE65, retinoid isomerohydrolase
1. 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 RPE65 protein is involved in a multi-step process called the visual 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 then helps convert all-trans retinal back to 11-cis retinal so the visual cycle can begin again.
2. Health Conditions Related to Genetic Changes
2.1. Leber congenital amaurosis
More than 30 mutations in the RPE65 gene have been found to cause Leber congenital amaurosis. Mutations in this gene account for 6 to 16 percent of all cases of this condition.
RPE65 gene mutations 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.
2.2. Other disorders
More than 20 mutations in the RPE65 gene have been identified in people with another eye disorder called retinitis pigmentosa. This condition is characterized by progressive vision loss caused by the gradual degeneration of light-sensing cells in the retina. The first sign of retinitis pigmentosa is usually a loss of night vision, which often becomes apparent in childhood. Over a period of years, the disease progresses to disrupt side (peripheral) vision and central vision. It may eventually lead to blindness.
The RPE65 gene mutations that cause retinitis pigmentosa disrupt RPE65 protein function, which leads to vision loss by impairing the visual cycle. Mutations in this gene appear to be an uncommon cause of retinitis pigmentosa; these genetic changes are responsible for only a small percentage of all cases.
Other Names for This Gene
RBP-binding membrane protein
retinal pigment epithelium specific protein 65
retinal pigment epithelium-specific 65 kDa protein
retinal pigment epithelium-specific protein 65kDa
retinitis pigmentosa 20 (autosomal recessive)
The entry is from https://medlineplus.gov/genetics/gene/rpe65
- Cai X, Conley SM, Naash MI. RPE65: role in the visual cycle, human retinaldisease, and gene therapy. Ophthalmic Genet. 2009 Jun;30(2):57-62. doi:10.1080/13816810802626399. Review.
- 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, ByrneBJ, Jacobson SG, Hauswirth WW. Human gene therapy for RPE65 isomerase deficiency activates the retinoid cycle of vision but with slow rod kinetics. Proc Natl AcadSci U S A. 2008 Sep 30;105(39):15112-7. doi: 10.1073/pnas.0807027105. Epub 2008Sep 22.
- den Hollander AI, Roepman R, Koenekoop RK, Cremers FP. Leber congenitalamaurosis: genes, proteins and disease mechanisms. Prog Retin Eye Res. 2008Jul;27(4):391-419. doi: 10.1016/j.preteyeres.2008.05.003. Epub 2008 Jun 1.Review.
- Morimura H, Fishman GA, Grover SA, Fulton AB, Berson EL, Dryja TP. Mutationsin the RPE65 gene in patients with autosomal recessive retinitis pigmentosa orleber congenital amaurosis. Proc Natl Acad Sci U S A. 1998 Mar 17;95(6):3088-93.
- Redmond TM, Poliakov E, Yu S, Tsai JY, Lu Z, Gentleman S. Mutation of keyresidues 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. Epub 2005 Sep 6.
- Redmond TM. Focus on Molecules: RPE65, the visual cycle retinol isomerase. ExpEye Res. 2009 May;88(5):846-7. doi: 10.1016/j.exer.2008.07.015. Epub 2008 Aug 14.Review.
- Thompson DA, Gyürüs P, Fleischer LL, Bingham EL, McHenry CL, Apfelstedt-Sylla E, Zrenner E, Lorenz B, Richards JE, Jacobson SG, Sieving PA, Gal A. Genetics andphenotypes of RPE65 mutations in inherited retinal degeneration. InvestOphthalmol Vis Sci. 2000 Dec;41(13):4293-9.
- Travis GH, Golczak M, Moise AR, Palczewski K. Diseases caused by defects inthe visual cycle: retinoids as potential therapeutic agents. Annu Rev PharmacolToxicol. 2007;47:469-512. Review.