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  • Title: C9-R95X polymorphism in patients with neovascular age-related macular degeneration.
    Author: Nishiguchi KM, Yasuma TR, Tomida D, Nakamura M, Ishikawa K, Kikuchi M, Ohmi Y, Niwa T, Hamajima N, Furukawa K, Terasaki H.
    Journal: Invest Ophthalmol Vis Sci; 2012 Jan 31; 53(1):508-12. PubMed ID: 22190594.
    Abstract:
    PURPOSE: A non-sense mutation at codon 95 in the gene encoding complement factor C9 (C9-R95X) is found most frequently among Japanese. The authors investigated the association between C9-R95X and Japanese patients with neovascular age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV). METHODS: The presence of the C9-R95X polymorphism was assessed by direct sequencing in Japanese patients with either PCV (n = 105) or neovascular AMD (n = 198) and 396 control subjects. Multivariate regression analyses were conducted. Photocoagulation was applied in the eyes of mice with a heterozygous defect in the C3 gene and control wild-type mice. Photocoagulation was also applied to wild-type mice before either anti-C9 antibody or isotype IgG was injected into the eyes. The eyes were collected later for measurement of vascular endothelial growth factor (VEGF) and histological evaluation of choroidal neovascularization (CNV). RESULTS: The frequency of those with one or two C9-R95X variants was lower in neovascular AMD (2.02%) than in PCV (5.71%) and controls (6.05%). The presence of C9-R95X conferred a 4.7-fold reduction (95% confidence interval, 1.2-18.1; P = 0.021) in the risk for neovascular AMD after adjusting for the major AMD risk factors. A heterozygous defect in the C3 gene was associated with the reduced growth of laser-induced CNV, as was intraocular injection of anti-C9 antibody. This reduced CNV growth was accompanied by a decreased level of secreted VEGF in the intraocular fluid. CONCLUSIONS: These findings support the notion that the haploinsufficiency of C9, a terminal complement complex component, engenders reduced intraocular secretion of VEGF and decreased risk for CNV development.
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