Oguchi Disease, Type 2 Clinical CharacteristicsOcular Features: The distinctive feature of Oguchi disease is the peculiar and distinctive discoloration of the fundus under various light conditions, known as the Mizuo phenomenon. Typically, the fundus assumes a golden or gray-white coloration under light adapted conditions but this disappears during acute dark adaptation and only reappears after prolonged time spent in darkness. Rod dark adaptation is markedly delayed while that of cones is normal. Single flash cone and 30Hz flicker responses are markedly reduced. Visual acuity, visual fields and color vision are all normal. A- and b-waves on single flash ERG are decreased or absent under lighted conditions but increase after prolonged dark adaptation. Night blindness is present from birth without progression. Systemic Features: No systemic abnormalities are associated with Oguchi disease. GeneticsOguchi type 2 disease is an autosomal recessive condition caused by mutations in the rhodopsin kinase (GRK1) gene (13q34) whose product works with arrestin in turning off rhodopsin after light activation as part of the dark adaptation mechanism. Oguchi type 1 disease (258100) is a similar form of congenital stationary nightblindness caused by mutations in the SAG gene. Pedigree: Autosomal recessiveTreatmentTreatment Options: No treatment is available. ReferencesArticle Title: Defects in the rhodopsin kinase gene in the Oguchi form of stationary night blindness Yamamoto S, Sippel KC, Berson EL, Dryja TP. Defects in the rhodopsin kinase gene in the Oguchi form of stationary night blindness. Nat Genet. 1997 Feb;15(2):175-8. PubMed ID: 9020843 A novel homozygous GRK1 mutation (P391H) in 2 siblings with Oguchi disease with markedly reduced cone responses Hayashi T, Gekka T, Takeuchi T, Goto-Omoto S, Kitahara K. A novel homozygous GRK1 mutation (P391H) in 2 siblings with Oguchi disease with markedly reduced cone responses. Ophthalmology. 2007 Jan;114(1):134-41. PubMed ID: 17070587 Read more about Oguchi Disease, Type 2
Defects in the rhodopsin kinase gene in the Oguchi form of stationary night blindness Yamamoto S, Sippel KC, Berson EL, Dryja TP. Defects in the rhodopsin kinase gene in the Oguchi form of stationary night blindness. Nat Genet. 1997 Feb;15(2):175-8. PubMed ID: 9020843
A novel homozygous GRK1 mutation (P391H) in 2 siblings with Oguchi disease with markedly reduced cone responses Hayashi T, Gekka T, Takeuchi T, Goto-Omoto S, Kitahara K. A novel homozygous GRK1 mutation (P391H) in 2 siblings with Oguchi disease with markedly reduced cone responses. Ophthalmology. 2007 Jan;114(1):134-41. PubMed ID: 17070587
