Dataset Information

Prevalence and phenotype associations of complement factor I mutations in geographic atrophy.

ABSTRACT: Rare variants in the complement factor I (CFI) gene, associated with low serum factor I (FI) levels, are strong risk factors for developing the advanced stages of age-related macular degeneration (AMD). No studies have been undertaken on the prevalence of disease-causing CFI mutations in patients with geographic atrophy (GA) secondary to AMD. A multicenter, cross-sectional, noninterventional study was undertaken to identify the prevalence of pathogenic rare CFI gene variants in an unselected cohort of patients with GA and low FI levels. A genotype-phenotype study was performed. Four hundred and sixty-eight patients with GA secondary to AMD were recruited to the study, and 19.4% (n = 91) demonstrated a low serum FI concentration (below 15.6 μg/ml). CFI gene sequencing on these patients resulted in the detection of rare CFI variants in 4.7% (n = 22) of recruited patients. The prevalence of CFI variants in patients with low serum FI levels and GA was 25%. Of the total patients recruited, 3.2% (n = 15) expressed a CFI variant classified as pathogenic or likely pathogenic. The presence of reticular pseudodrusen was detected in all patients with pathogenic CFI gene variants. Patients with pathogenic CFI gene variants and low serum FI levels might be suitable for FI supplementation in therapeutic trials.

SUBMITTER: Khan AH

PROVIDER: S-EPMC9290714 | biostudies-literature | 2021 Sep

REPOSITORIES: biostudies-literature

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Prevalence and phenotype associations of complement factor I mutations in geographic atrophy.

Khan Adnan H AH Sutton Janice J Cree Angela J AJ Khandhadia Samir S De Salvo Gabriella G Tobin John J Prakash Priya P Arora Rashi R Amoaku Winfried W Charbel Issa Peter P MacLaren Robert E RE Bishop Paul N PN Peto Tunde T Mohamed Quresh Q Steel David H DH Sivaprasad Sobha S Bailey Clare C Menon Geeta G Kavanagh David D Lotery Andrew J AJ

Human mutation 20210629 9

Rare variants in the complement factor I (CFI) gene, associated with low serum factor I (FI) levels, are strong risk factors for developing the advanced stages of age-related macular degeneration (AMD). No studies have been undertaken on the prevalence of disease-causing CFI mutations in patients with geographic atrophy (GA) secondary to AMD. A multicenter, cross-sectional, noninterventional study was undertaken to identify the prevalence of pathogenic rare CFI gene variants in an unselected coh ...[more]

PMID: 34153144

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Project description:PurposeTo establish the safety, tolerability, pharmacokinetics, and pharmacodynamics of an intravitreal injection of recombinant human complement factor H (CFH), GEM103, in individuals with genetically defined age-related macular degeneration (AMD) and geographic atrophy (GA).DesignPhase I single ascending-dose, open-label clinical trial (ClinicalTrials.gov identifier, NCT04246866).ParticipantsTwelve individuals 50 years of age or older with a confirmed diagnosis of foveal GA in the study eye.MethodsParticipants were assigned to the increasing dose cohorts and received 1 50-μl intravitreal injection of GEM103 at doses of 50 μg/eye, 100 μg/eye, 250 μg/eye, or 500 μg/eye; dose escalation was dependent on the occurrence of dose-limiting toxicities.Main outcome measuresSafety assessments included ocular and systemic adverse events (AEs), ocular examinations, clinical laboratory and vital signs, and serum antidrug antibody levels. Biomarkers, measured in the aqueous humor (AH), included CFH and complement activation biomarkers factor Ba and complement component 3a.ResultsNo dose-limiting toxicities were reported, enabling escalation to the maximum study dose. No anti-GEM103 antidrug antibodies were detected during the study. Four participants experienced AEs; these were nonserious, mild or moderate in severity, and unrelated to GEM103. The AEs in 2 of these participants were related to the intravitreal injection procedure. No clinically significant ophthalmic changes and no ocular inflammation were observed. Visual acuity was maintained and stable throughout the 8-week follow-up period. No choroidal neovascularization occurred. CFH levels increased in a dose-dependent manner after GEM103 administration with supraphysiological levels observed at week 1; levels were more than baseline for 8 weeks or more in all participants receiving single doses of 100 μg or more. Complement activation biomarkers were reduced 7 days after dose administration.ConclusionsA single intravitreal administration of GEM103 (up to 500 μg/eye) was well tolerated in individuals with GA. Of the few mild or moderate AEs reported, none were determined to be related to GEM103. No intraocular inflammation or choroidal neovascularization developed. CFH levels in AH were increased and stable for 8 weeks, with pharmacodynamic data suggesting that GEM103 restored complement regulation. These results support further development in a repeat-dose trial in patients with GA with AMD.

Project description:PurposeTo evaluate the effect of eculizumab, a systemic inhibitor of complement component (C5), on the growth of geographic atrophy (GA) in patients with age-related macular degeneration (AMD).DesignProspective, double-masked, randomized clinical trial.ParticipantsPatients with GA measuring from 1.25 to 18 mm(2) based on spectral-domain optical coherence tomography imaging.MethodsPatients were randomized 2:1 to receive intravenous eculizumab or placebo over 6 months. In the eculizumab treatment arm, the first 10 patients received a low-dose regimen of 600 mg weekly for 4 weeks followed by 900 mg every 2 weeks until week 24, and the next 10 patients received a high-dose regimen of 900 mg weekly for 4 weeks followed by 1200 mg every 2 weeks until week 24. The placebo group was infused with saline. Patients were observed off treatment for an additional 26 weeks. Both normal-luminance and low-luminance visual acuities were measured throughout the study, and the low-luminance deficits were calculated as the difference between the letter scores.Main outcome measuresChange in area of GA at 26 weeks.ResultsThirty eyes of 30 patients were enrolled. Eighteen fellow eyes also met inclusion criteria and were analyzed as a secondary endpoint. For the 30 study eyes, mean square root of GA area measurements ± standard deviation at baseline were 2.55 ± 0.94 and 2.02 ± 0.74 mm in the eculizumab and placebo groups, respectively (P = 0.13). At 26 weeks, GA enlarged by a mean of 0.19 ± 0.12 and 0.18 ± 0.15 mm in the eculizumab and placebo groups, respectively (P = 0.96). At 52 weeks of follow-up, GA enlarged by a mean of 0.37 ± 0.22 mm in the eculizumab-treated eyes and by a mean of 0.37 ± 0.21 mm in the placebo group (P = 0.93, 2 sample t test). None of the eyes converted to wet AMD. No drug-related adverse events were identified.ConclusionsSystemic complement inhibition with eculizumab was well tolerated through 6 months but did not decrease the growth rate of GA significantly. However, there was a statistically significant correlation between the low-luminance deficit at baseline and the progression of GA over 6 months.

Project description:In geographic atrophy (GA), the non-neovascular end stage of age-related macular degeneration (AMD), the macular retinal pigment epithelium (RPE) progressively degenerates. Membrane cofactor protein (MCP, CD46) is the only membrane-bound regulator of complement expressed on the human RPE basolateral surface. Based on evidence of the role of complement in AMD, we hypothesized that altered CD46 expression on the RPE would be associated with GA development and/or progression. Here we report the timeline of CD46 protein expression changes across the GA transition zone, relative to control eyes, and relative to events in other chorioretinal layers. Eleven donor eyes (mean age 87.0 ± 4.1 yr) with GA and 5 control eyes (mean age 84.0 ± 8.9 yr) without GA were evaluated. Macular cryosections were stained with PASH for basal deposits, von Kossa for calcium, and for CD46 immunoreactivity. Internal controls for protein expression were provided by an independent basolateral protein, monocarboxylate transporter 3 (MCT3) and an apical protein, ezrin. Within zones defined by 8 different semi-quantitative grades of RPE morphology, we determined the location and intensity of immunoreactivity, outer segment length, and Bruch's membrane calcification. Differences between GA and control eyes and between milder and more severe RPE stages in GA eyes were assessed statistically. Increasing grades of RPE degeneration were associated with progressive loss of polarity and loss of intensity of staining of CD46, beginning with the stages that are considered normal aging (grades 0-1). Those GA stages with affected CD46 immunoreactivity exhibited basal laminar deposit, still-normal photoreceptors, and concomitant changes in control protein expression. Activated or anteriorly migrated RPE (grades 2-3) exhibited greatly diminished CD46. Changes in RPE CD46 expression thus occur early in GA, before there is evidence of morphological RPE change. At later stages of degeneration, CD46 alterations occur within a context of altered RPE polarity. These changes precede degeneration of the overlying retina and suggest that therapeutic interventions be targeted to the RPE.

Project description:PurposeThe accuracy of predicting conversion from early-stage age-related macular degeneration (AMD) to the advanced stages of choroidal neovascularization (CNV) or geographic atrophy (GA) was evaluated to determine whether inclusion of clinically relevant genetic markers improved accuracy beyond prediction using phenotypic risk factors alone.DesignCohort study.ParticipantsWhite, non-Hispanic subjects participating in the Age-Related Eye Disease Study (AREDS) sponsored by the National Eye Institute consented to provide a genetic specimen. Of 2415 DNA specimens available, 940 were from disease-free subjects and 1475 were from subjects with early or intermediate AMD.MethodsDNA specimens from study subjects were genotyped for 14 single nucleotide polymorphisms (SNPs) in genes shown previously to associate with CNV: ARMS2, CFH, C3, C2, FB, CFHR4, CFHR5, and F13B. Clinical demographics and established disease associations, including age, sex, smoking status, body mass index (BMI), AREDS treatment category, and educational level, were evaluated. Four multivariate logistic models (phenotype; genotype; phenotype + genotype; and phenotype + genotype + demographic + environmental factors) were tested using 2 end points (CNV, GA). Models were fitted using Cox proportional hazards regression to use time-to-disease onset data.Main outcome measuresBrier score (measure of accuracy) was used to identify the model with the lowest prediction error in the training set. The most accurate model was subjected to independent statistical validation, and final model performance was described using area under the receiver operator curve (AUC) or C-statistic.ResultsThe CNV prediction models that combined genotype with phenotype with or without age and smoking revealed superior performance (C-statistic = 0.96) compared with the phenotype model based on the simplified severity scale and the presence of CNV in the nonstudy eye (C-statistic = 0.89; P<0.01). For GA, the model that combined genotype with phenotype demonstrated the highest performance (AUC = 0.94). Smoking status and ARMS2 genotype had less of an impact on the prediction of GA compared with CNV.ConclusionsInclusion of genotype assessment improves CNV prediction beyond that achievable with phenotype alone and may improve patient management. Separate assessments should be used to predict progression to CNV and GA because genetic markers and smoking status do not equally predict both end points.Financial disclosure(s)Proprietary or commercial disclosure may be found after the references.

Project description:IntroductionGeographic atrophy (GA) is the advanced form of the non-neovascular ('dry') type of age-related macular degeneration (AMD). Previously untreatable, complement inhibitors delivered by regular intravitreal injections have recently been demonstrated to slow down the progression of GA lesions in phase 3 trials. One such treatment, Syfovre (pegcetacoplan), was approved by the US Food and Drug Administration in February 2023. These therapies slow down, but do not stop or reverse, the progression of GA; they may also increase the risk of developing the neovascular ('wet') type of AMD. In light of these developments, this study aims to quantify the acceptability of these new intravitreal injection treatments to patients with GA in the UK and explore factors that may influence the acceptability of these treatments.Methods and analysisIn this cross-sectional, non-interventional study, the primary objective is to determine the proportion of patients with GA that find regular intravitreal therapy acceptable for slowing the progression of GA. We will use a validated acceptability questionnaire in order to quantify the acceptability of new treatments among patients with GA. The correlation between acceptability and functional and structural biomarkers of GA will be established. We will also explore demographic, general health and ocular factors that may influence acceptability. 180 individuals with a diagnosis of GA will be recruited from 7 to 8 participating National Health Service trusts across the UK. Multiple regression analysis will be conducted to determine the simultaneous effects of multiple factors on patient acceptability.Ethics and disseminationThe study received ethical approval from the Health Research Authority on 14 March 2023 (IRAS Project ID: 324854). Findings will be disseminated through peer-reviewed publications and conference presentations to the medical retina community, as well as through dialogue with patients and macular disease charities.

Dataset Information

Prevalence and phenotype associations of complement factor I mutations in geographic atrophy.

Publications

Prevalence and phenotype associations of complement factor I mutations in geographic atrophy.

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