Dataset Information

Phenotypic Characterization of Complement Factor H R1210C Rare Genetic Variant in Age-Related Macular Degeneration.

ABSTRACT: IMPORTANCE:The complement factor H R1210C rare variant confers the strongest genetic risk for age-related macular degeneration and earlier age at onset; however, its associated phenotype has not been well characterized. OBJECTIVE:To describe specific fundus features of a white population with the R1210C rare variant. DESIGN, SETTING, AND PARTICIPANTS:Fundus features specific for diagnosis and disease staging were retrospectively characterized by systematic review of all available fundus images for each patient, including color photography, fluorescein angiography, fundus autofluorescence, and optical coherence tomography, at a tertiary ophthalmologic referral center. For this retrospective observational study conducted from 2012 to 2014, enrolled patients with the variant and their family members without the variant were identified from the Age-Related Macular Degeneration Study for a family-based study arm. For patients with the variant but without a family member enrolled in the study, age-matched comparison individuals without the variant were selected randomly from the database. MAIN OUTCOMES AND MEASURES:The presence of drusen in the macula (macular drusen score) and estimated number (total macular drusen score) were assessed. The presence of drusen in the extramacular regions (extramacular drusen score), pigmentary abnormalities, and disease staging were also evaluated. Binary logistic regression models were used to evaluate the association between rare variant status and ocular phenotypes. RESULTS:Images from a total of 143 patients (283 eyes), including 62 patients with the rare variant, were analyzed. Drusen score covariates were associated with the R1210C rare variant. A larger proportion of patients carrying the variant had the highest level of macular and total macular drusen scores compared with those without the variant (57.9% vs 16.7% and 52.9% vs 14.2%, respectively; P for trend?

SUBMITTER: Ferrara D

PROVIDER: S-EPMC6516461 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature

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Phenotypic Characterization of Complement Factor H R1210C Rare Genetic Variant in Age-Related Macular Degeneration.

Ferrara Daniela D Seddon Johanna M JM

JAMA ophthalmology 20150701 7

<h4>Importance</h4>The complement factor H R1210C rare variant confers the strongest genetic risk for age-related macular degeneration and earlier age at onset; however, its associated phenotype has not been well characterized.<h4>Objective</h4>To describe specific fundus features of a white population with the R1210C rare variant.<h4>Design, setting, and participants</h4>Fundus features specific for diagnosis and disease staging were retrospectively characterized by systematic review of all ava ...[more]

PMID: 25880396

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Project description:PurposeGenetic variants in the complement factor H gene (CFH) have been consistently implicated in age-related macular degeneration (AMD) risk. However, their functional effects are not fully characterized. We previously identified a rare, AMD-associated variant in CFH (P503A, rs570523689) in 19 Amish individuals, but its functional consequences were not investigated.MethodsWe performed genotyping for CFH P503A in 1326 Amish individuals to identify additional risk allele carriers. We examined differences for age at AMD diagnosis between carriers and noncarriers. In blood samples from risk allele carriers and noncarriers, we quantified (i) CFH RNA expression, (ii) CFH protein expression, and (iii) C-reactive protein (CRP) expression. Potential changes to the CFH protein structure were interrogated computationally with Phyre2 and Chimera software programs.ResultsWe identified 39 additional carriers from Amish communities in Ohio and Indiana. On average, carriers were younger than noncarriers at AMD diagnosis, but this difference was not significant. CFH transcript and protein levels in blood samples from Amish carriers and noncarriers were also not significantly different. CRP levels were also comparable in plasma samples from carriers and noncarriers. Computational protein modeling showed slight changes in the CFH protein conformation that were predicted to alter interactions between the CFH 503 residue and other neighboring residues.ConclusionsIn total, we have identified 58 risk allele carriers for CFH P503A in the Ohio and Indiana Amish. Although we did not detect significant differences in age at AMD diagnosis or expression levels of CFH in blood samples from carriers and noncarriers, we observed modest structural changes to the CFH protein through in silico modeling. Based on our functional and computational observations, we hypothesize that CFH P503A may affect CFH binding or function rather than expression, which would require additional research to confirm.

Project description:Purpose To evaluate associations between rare dysfunctional complement factor I (CFI) genetic variant status and progression to advanced age-related macular degeneration (AAMD), geographic atrophy (GA), and neovascular disease (NV). Design Prospective, longitudinal study Participants Patients aged 55 to 80 years at baseline identifying as White with non-AAMD in 1 or both eyes at baseline were included. Follow-up grades were assigned as early, intermediate, or AAMD (GA or NV). CFI variants were categorized using genotyping and sequencing platforms. Methods Analyses were performed using the Seddon Longitudinal Cohort Study (N = 2116 subjects, 3901 eyes, and mean follow-up of 8.3 years) and the Age-Related Eye Disease Study (N = 2837 subjects, 5200 eyes, and mean follow-up of 9.2 years). CFI rare variants associated with low serum factor I (FI) protein levels and decreased FI function (type 1), other AMD genetic variants, and demographic, behavioral, and ocular factors were evaluated. Generalized estimating equations methods were used to assess the association between CFI rare variants and progression, independent of other genetic variants and covariates. Main Outcome Measures Progression to AAMD, GA, or NV. Results In the prospective cohort of 4953 subjects (9101 eyes with non-AAMD at baseline), 1% were type 1 rare CFI carriers. Over 12 years, progression to AAMD was 44% for carriers and 20% for noncarriers (P < 0.001), 30% of carriers versus 10% of noncarriers progressed to GA (P < 0.001), and 18% of carriers compared with 11% of noncarriers progressed to NV (P = 0.049). CFI carriers were more likely to have a family history of AMD (P for trend = 0.035) and a higher baseline AMD grade (P < 0.001). After adjusting for all covariates, CFI carrier status was associated with progression to GA (odds ratio [OR] = 1.91; 95% confidence interval [CI] = 1.03, 3.52) but not NV (OR = 0.96). Higher body mass index was associated with progression among CFI carriers (body mass index ≥ 25 vs. < 25; OR = 5.8; 95% CI 1.5, 22.3) but not for noncarriers (OR = 1.1; 95% CI = 0.9, 1.3), with P_interaction = 0.011. Conclusions Results suggest that carriers of rare dysfunctional type 1 CFI variants are at higher risk for progression to AAMD with GA. Financial Disclosure(s) Proprietary or commercial disclosure may be found after the references.

Project description:ImportanceRare variants in the complement factor H (CFH) gene and their association with age-related macular degeneration (AMD) have been described. However, there is limited literature on the phenotypes accompanying these rare variants. Phenotypical characteristics could help ophthalmologists select patients for additional genetic testing.ObjectiveTo describe the phenotypical characteristics of patients with AMD carrying a rare variant in the CFH gene.Design, setting, and participantsIn this cross-sectional study, we searched the genetic database of the department of ophthalmology at the Radboudumc (tertiary ophthalmologic referral center) and the European Genetic Database for patients with AMD with a rare genetic variant in the CFH gene. Patient recruitment took place from March 30, 2006, to February 18, 2013, and data were analyzed from November 30, 2015, to May 8, 2017. Phenotypical features on fundus photographs of both eyes of patients were graded by 2 independent reading center graders masked for carrier status.Main outcomes and measuresDifferences in phenotypical characteristics between rare variant carriers and noncarriers were analyzed using univariable generalized estimated equations logistic regression models accounting for intereye correlation.ResultsAnalyses included 100 eyes of 51 patients with AMD carrying a CFH variant (mean [SD] age, 66.7 [12.1] years; 64.7% female) and 204 eyes of 102 age-matched noncarriers (mean [SD] age, 67.1 [11.8] years; 54.9% female). Carrying a rare pathogenic CFH variant was associated with larger drusen area (odds ratio range, 6.98 [95% CI, 2.04-23.89] to 18.50 [95% CI, 2.19-155.99]; P = .002), presence of drusen with crystalline appearance (odds ratio, 3.24; 95% CI, 1.24-8.50; P = .02), and drusen nasal to the optic disc (odds ratio range, 4.03 [95% CI, 1.70-9.56] to 7.42 [95% CI, 0.65-84.84]; P = .003).Conclusions and relevanceIdentification of rare CFH variant carriers may be important for upcoming complement-inhibiting therapies. Patients with an extensive drusen area, drusen with crystalline appearance, and drusen nasal to the optic disc are more likely to have a rare variant in the CFH gene. However, it is not likely that carriers can be discriminated from noncarriers based solely on phenotypical characteristics from color fundus images. Therefore, ophthalmologists should consider genetic testing in patients with these phenotypic characteristics in combination with other patient characteristics, such as early onset, cuticular drusen on fluorescein angiography, and family history of AMD.

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.

Dataset Information

Phenotypic Characterization of Complement Factor H R1210C Rare Genetic Variant in Age-Related Macular Degeneration.

Publications

Phenotypic Characterization of Complement Factor H R1210C Rare Genetic Variant in Age-Related Macular Degeneration.

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