Dataset Information

The complement component 5 gene and age-related macular degeneration.

ABSTRACT:

Objective

To investigate the association between variants in the complement component 5 (C5) gene and age-related macular degeneration (AMD).

Design

Separate and combined data from 3 large AMD case-control studies and a prospective population-based study (The Rotterdam Study).

Participants

A total of 2599 AMD cases and 3458 ethnically matched controls.

Methods

Fifteen single nucleotide polymorphisms (SNPs) spanning the C5 gene were initially genotyped in 375 cases and 199 controls from The Netherlands (The Amsterdam/Rotterdam-Netherlands [AMRO-NL] study population). Replication testing of selected SNPs was performed in the Rotterdam Study (NL) and study populations from Southampton, United Kingdom (UK), and New York, United States (US).

Main outcome measures

Early and late stages of prevalent and incident AMD, graded according to (a modification of) the international grading and classification system of AMD.

Results

Significant allelic or genotypic associations between 8 C5 SNPs and AMD were found in the AMRO-NL study and this risk seemed to be independent of CFH Y402H, LOC387715 A69S, age, and gender. None of these findings could be confirmed consistently in 3 replication populations.

Conclusions

Although the complement pathway, including C5, plays a crucial role in AMD, and the C5 protein is present in drusen, no consistent significant associations between C5 SNPs and AMD were found in any of these studies. The implications for genetic screening of AMD are discussed.

SUBMITTER: Baas DC

PROVIDER: S-EPMC2830367 | biostudies-literature | 2010 Mar

REPOSITORIES: biostudies-literature

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Publications

The complement component 5 gene and age-related macular degeneration.

Baas Dominique C DC Ho Lintje L Ennis Sarah S Merriam Joanna E JE Tanck Michael W T MW Uitterlinden André G AG de Jong Paulus T V M PT Cree Angela J AJ Griffiths Helen L HL Rivadeneira Fernando F Hofman Albert A van Duijn Cornelia C Smith R Theodore RT Barile Gaetano R GR Gorgels Theo G M F TG Vingerling Johannes R JR Klaver Caroline C W CC Lotery Andrew J AJ Allikmets Rando R Bergen Arthur A B AA

Ophthalmology 20091222 3

<h4>Objective</h4>To investigate the association between variants in the complement component 5 (C5) gene and age-related macular degeneration (AMD).<h4>Design</h4>Separate and combined data from 3 large AMD case-control studies and a prospective population-based study (The Rotterdam Study).<h4>Participants</h4>A total of 2599 AMD cases and 3458 ethnically matched controls.<h4>Methods</h4>Fifteen single nucleotide polymorphisms (SNPs) spanning the C5 gene were initially genotyped in 375 cases an ...[more]

PMID: 20022638

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Project description:BACKGROUND:Given the relatively high prevalence of age-related macular degeneration (AMD) and the increased incidence of AMD as populations age, the results of trials of novel treatments are awaited with much anticipation. The complement cascade describes a series of proteolytic reactions occurring throughout the body that generate proteins with a variety of roles including the initiation and promotion of immune reactions against foreign materials or micro-organisms. The complement cascade is normally tightly regulated, but much evidence implicates complement overactivity in AMD and so it is a logical therapeutic target in the treatment of AMD. OBJECTIVES:To assess the effects and safety of complement inhibitors in the prevention or treatment of advanced AMD. SEARCH METHODS:We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2013, Issue 11), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to November 2013), EMBASE (January 1980 to November 2013), Allied and Complementary Medicine Database (AMED) (January 1985 to November 2013), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to November 2013), OpenGrey (System for Information on Grey Literature in Europe) (www.opengrey.eu/), Web of Science Conference Proceedings Citation Index - Science (CPCI-S) (January 1990 to November 2013), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 21 November 2013. We also performed handsearching of proceedings, from 2012 onwards, of meetings and conferences of specific professional organisations. SELECTION CRITERIA:We planned to include randomised controlled trials (RCTs) with parallel treatment groups which investigated either the prevention or treatment of advanced AMD by inhibition of the complement cascade. DATA COLLECTION AND ANALYSIS:Two authors (MW and GMcK) independently evaluated all the titles and abstracts resulting from the searches. We contacted companies running clinical trials which had not yet reported results to request information. Since no trials met our inclusion criteria, we undertook no assessment of quality or meta-analysis. MAIN RESULTS:We identified and screened 317 references but there were no published RCTs that met the inclusion criteria. We identified two ongoing studies: one phase I study and one phase II study. AUTHORS' CONCLUSIONS:There is insufficient information at present to generate evidence-based recommendations on the potential safety and efficacy of complement inhibitors for prevention or treatment of AMD. However we anticipate the results of ongoing trials.

Project description:PurposeThe complement system has been implicated in the pathogenesis of age-related macular degeneration (AMD). Complement factor I (CFI) is a serum protease that inhibits all complement pathways. A previous multicenter study identified a single missense CFI mutation (p.Gly119Arg) in 20/3,567 (0.56%) of AMD cases versus 1/3,937 (0.025%) of controls, thus suggesting that this mutation confers a high risk of AMD. A second CFI mutation, p.Gly188Ala, was identified in one patient with AMD.MethodsWe screened 521 unrelated AMD cases and 627 controls for the p.Gly119Arg and p.Gly188Ala variants. All participants were Caucasian and >55 years, and recruited through Southampton Eye Unit or research clinics in Guernsey. All participants underwent dilated fundal examination by an experienced retinal specialist. SNP assays were performed using KASP™ biochemistry.ResultsThe p.Gly119Arg mutation was identified in 7/521 AMD cases compared to 1/627 age-matched controls (odds ratio [OR] = 8.47, confidence interval [CI] = 1.04-69.00, p = 0.027). There was a varied phenotype among the seven cases with the mutation, which was present in 4/254 (1.6%) cases with active or end-stage wet AMD and 3/267 dry AMD cases (1.1%). The p.Gly188Ala substitution was identified in 1/521 cases and 1/627 controls.ConclusionsOur results identified a much higher frequency of heterozygosity for p.Gly119Arg in both cases and controls than in previous studies. Of note is that our sub-cohort from Guernsey had a particularly high frequency of p.Gly119Arg heterozygosity in affected individuals (4%) compared to our sub-cohort from the mainland (0.71%). Although these data support the conclusions of van de Ven et al. that the p.Gly119Arg substitution confers a high risk of AMD, our data suggest that this missense mutation is not as rare or as highly penetrant as previously reported. There was no difference in frequency for a second CFI variant, p.Gly188Ala, between the cases and the controls.

Project description:Age-related macular degeneration (AMD) is the leading cause of blindness in the Western world. AMD is a multifactorial disorder but complement-mediated inflammation at the level of the retina plays a pivotal role. Oral zinc supplementation can reduce the progression of AMD but the precise mechanism of this protective effect is as yet unclear. We investigated whether zinc supplementation directly affects the degree of complement activation in AMD and whether there is a relation between serum complement catabolism during zinc administration and the complement factor H (CFH) gene or the Age-Related Maculopathy susceptibility 2 (ARMS2) genotype. In this open-label clinical study, 72 randomly selected AMD patients in various stages of AMD received a daily supplement of 50 mg zinc sulphate and 1 mg cupric sulphate for three months. Serum complement catabolism-defined as the C3d/C3 ratio-was measured at baseline, throughout the three months of supplementation and after discontinuation of zinc administration. Additionally, downstream inhibition of complement catabolism was evaluated by measurement of anaphylatoxin C5a. Furthermore, we investigated the effect of zinc on complement activation in vitro. AMD patients with high levels of complement catabolism at baseline exhibited a steeper decline in serum complement activation (p<0.001) during the three month zinc supplementation period compared to patients with low complement levels. There was no significant association of change in complement catabolism and CFH and ARMS2 genotype. In vitro zinc sulphate directly inhibits complement catabolism in hemolytic assays and membrane attack complex (MAC) deposition on RPE cells. This study provides evidence that daily administration of 50 mg zinc sulphate can inhibit complement catabolism in AMD patients with increased complement activation. This could explain part of the mechanism by which zinc slows AMD progression.The Netherlands National Trial Register NTR2605.

Dataset Information

The complement component 5 gene and age-related macular degeneration.

Objective

Design

Participants

Methods

Main outcome measures

Results

Conclusions

Publications

The complement component 5 gene and age-related macular degeneration.

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