Dzenita Smailhodzic

A functional variant in the CFI gene confers a high risk of age-related macular degeneration

Up to half of the heritability of age-related macular degeneration (AMD) is explained by common variants. Here, we report the identification of a rare, highly penetrant missense mutation in CFI encoding a p.Gly119Arg substitution that confers high risk of AMD (P = 3.79 × 10−6; odds ratio (OR) = 22.20, 95% confidence interval (CI) = 2.98–164.49). Plasma and sera from cases carrying the p.Gly119Arg substitution mediated the degradation of C3b, both in the fluid phase and on the cell surface, to a lesser extent than those from controls. Recombinant protein studies showed that the Gly119Arg mutant protein is both expressed and secreted at lower levels than wild-type protein. Consistent with these findings, human CFI mRNA encoding Arg119 had reduced activity compared to wild-type mRNA encoding Gly119 in regulating vessel thickness and branching in the zebrafish retina. Taken together, these findings demonstrate that rare, highly penetrant mutations contribute to the genetic burden of AMD.

Risk Alleles in CFH and ARMS2 Are Independently Associated with Systemic Complement Activation in Age-related Macular Degeneration

PURPOSE Systemic complement activation is associated with age-related macular degeneration (AMD) and has mainly been attributed to a risk allele in the complement factor H (CFH) gene. Whether other important AMD genes also influence complement activation is unclear. In the present case-control study, complement activity and concentrations of complement components and their activation products are measured in AMD patients and in unaffected controls and correlated with genetic variants in the CFH, ARMS2, C3, CFI, and CFB genes. DESIGN Case-control study. PARTICIPANTS A cohort of 197 confirmed AMD patients and 150 unaffected age-matched controls were recruited prospectively for the study. METHODS Hemolytic complement assays (AP50, CP50, and LP50), complement components (C3, CFB, CFI, and CFH), and the activation products (C3d, C5a, and SC5b-9) were analyzed in serum or plasma. The DNA samples were genotyped for 5 single nucleotide polymorphisms (SNPs) previously associated with AMD in the CFH, ARMS2, C3, CFB, and CFI genes. MAIN OUTCOME MEASURES Complement concentrations and their associations with SNPs in the CFH, ARMS2, C3, CFB, and CFI genes. RESULTS The AMD patients had increased activation of the alternative complement pathway (P = 0.003) and elevated levels of complement activation components C3d (P<0.0001) and C5a (P<0.0001), CFB (P<0.0001), and an increased C3d/C3 ratio (P<0.0001) calculated as a measure of C3 activation. While the CFH risk genotype was significantly associated with the elevated C3d/C3 ratios obtained, in the absence of CFH risk alleles the ARMS2 risk genotype also showed significantly increased levels of complement activation (P = 0.013). Furthermore, the carriers of the CFB protective allele had lower CFB concentrations. CONCLUSIONS The current study found evidence showing that in AMD risk alleles in CFH and ARMS2 are independently associated with complement activation. Especially the C3d/C3 ratio seems to be a strong marker for AMD. The findings suggest that CFH and ARMS2 share a common pathway in the pathogenesis of AMD.

Cumulative Effect of Risk Alleles in CFH, ARMS2, and VEGFA on the Response to Ranibizumab Treatment in Age-Related Macular Degeneration

PURPOSE Intravitreal ranibizumab injections currently are the standard treatment for neovascular age-related macular degeneration (AMD). However, a broad range of response rates have been observed, the reasons for which are poorly understood. This pharmacogenetic study evaluated the impact of high-risk alleles in CFH, ARMS2, VEGFA, vascular endothelial growth factor (VEGF) receptor KDR, and genes involved in angiogenesis (LRP5, FZD4) on the response to ranibizumab treatment and on the age of treatment onset. In contrast to previous studies, the data were stratified according to the number of high-risk alleles to enable the study of the combined effects of these genotypes on the treatment response. DESIGN Case series study. PARTICIPANTS A cohort of 420 eyes of 397 neovascular AMD patients. METHODS The change in visual acuity (VA) between baseline and after 3 ranibizumab injections was calculated. Genotyping of single nucleotide polymorphisms in the CFH, ARMS2, VEGFA, KDR, LPR5, and FZD4 genes was performed. Associations were assessed using linear mixed models. MAIN OUTCOME MEASURES The VA change after 3 ranibizumab injections and the age of neovascular disease onset. RESULTS After ranibizumab treatment, AMD patients without risk alleles in the CFH and ARMS2 genes (4.8%) demonstrated a mean VA improvement of 10 Early Treatment Diabetic Retinopathy Study (ETDRS) letters, whereas no VA improvement was observed in AMD patients with 4 CFH and ARMS2 risk alleles (6.9%; P = 0.014). Patients with 4 high-risk alleles in CFH and ARMS2 were 5.2 years younger than patients with 1 or 2 risk alleles, respectively (63.5%; P<0.0001). The mean age at which the first ranibizumab treatment was carried out among AMD patients with all 6 risk alleles in CFH, ARMS2, and VEGFA was 65.9 years (2%) versus 75.3 years in patients with 0 or 1 high-risk allele (8.8%; P = 0.001). After ranibizumab treatment, patients with 6 high-risk alleles demonstrated a mean VA loss of 10 ETDRS letters (P<0.0001). CONCLUSIONS This study evaluated the largest pharmacogenetic AMD cohort reported to date. A cumulative effect of high-risk alleles in CFH, ARMS2, and VEGFA seems to be associated with a younger age of onset in combination with poor response rates to ranibizumab treatment.

Zinc Supplementation Inhibits Complement Activation in Age-Related Macular Degeneration

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. Trial Registration The Netherlands National Trial Register NTR2605

Genetic, behavioral, and sociodemographic risk factors for second eye progression in age-related macular degeneration.

PURPOSE This study was conducted to investigate the correlation of genetic, sociodemographic, and behavioral risk factors with second eye progression to end-stage AMD. METHODS One hundred and eight patients with end-stage AMD in one or both eyes were included in a retrospective time-to-event analysis of the onset of end-stage AMD in the second eye. Multivariate Cox regression survival analysis was performed for sex, age, smoking, body mass index (BMI), education, and 16 single nucleotide polymorphisms (SNPs) associated with AMD. RESULTS Except for education, all sociodemographic and behavioral risk factors analyzed were significantly associated with a more rapid progression toward second eye involvement. Hazard ratios (HRs) were 2.6 (95% confidence interval [CI], 1.4-5.0) for female sex; 5.0 (95% CI, 2.0-12.5) for age >80; 2.2 (95% CI, 1.1-4.1) for BMI >30; and 4.4 (95% CI, 1.4-14.3) for >40 pack years, compared with the referent groups. Carriers of the lipoprotein lipase (LPL; rs12678919) risk alleles were at risk for more rapid progression to end-stage AMD in the second eye compared with the referent wild-type genotype (HR 2.0; 95% CI, 1.0-3.6). For complement factor I (CFI; rs10033900), homozygous carriers of the risk allele progressed faster than wild-type individuals (HR 2.2; 95% CI, 1.1-4.3). CONCLUSIONS Sociodemographic, behavioral, and genetic risk factors are associated with the rate of second eye progression toward end-stage AMD. The findings of this study underline the importance of lifestyle factors and the complement pathway in AMD progression and suggest a role of the high-density-lipoprotein metabolism in second eye progression.

A genetic variant in NRP1 is associated with worse response to ranibizumab treatment in neovascular age-related macular degeneration.

Objective The aim of the study was to investigate the role of single-nucleotide polymorphisms (SNPs) located in the neuropilin-1 (NRP1) gene in treatment response to antivascular endothelial growth factor (VEGF) therapy for neovascular age-related macular degeneration (nvAMD). Methods Four SNPs in the NRP1 gene (rs2229935, rs2247383, rs2070296, and rs2804495) were genotyped in a study cohort of 377 nvAMD patients who received the loading dose of three monthly ranibizumab injections. Treatment response was assessed as the change in visual acuity after three monthly loading injections compared with baseline. Results SNP rs2070296 was associated with change in visual acuity after 3 months of treatment. Patients carrying the GA or AA genotypes performed significantly worse than individuals carrying the GG genotype (P=0.01). A cumulative effect of rs2070296 in the NRP1 gene and rs4576072 located in the VEGF receptor 2 (VEGFR2 or KDR) gene, previously associated with treatment response, was observed. Patients carrying two risk alleles performed significantly worse than patients carrying zero or one risk allele (P=0.03), and patients with more than two risk alleles responded even worse to the therapy (P=3×10–3). The combined effect of these two SNPs on the response was also seen after 6 and 12 months of treatment. Conclusion This study suggests that genetic variation in NRP1, a key molecule in VEGFA-driven neovascularization, influences treatment response to ranibizumab in nvAMD patients. The results of this study may be used to generate prediction models for treatment response, which in the future may help tailor medical care to individual needs.

Prognostic Factors for Long Term Visual Acuity Outcome after Ranibizumab Therapy in Patients with Neovascular Age-Related Macular Degeneration

Purpose: To evaluate whether spectral domain optical coherence tomography (SDOCT) and fluorescein angiography (FA) findings are predictive of visual acuity (VA) outcome after ranibizumab for neovascular age-related macular degeneration (NVAMD). Methods: Best corrected VA of 72 previously untreated eyes with NVAMD were retrospectively collected at baseline, after 3 injections and at 12, 24 and 36 months follow-up, if available. FA and SDOCT images at baseline were qualitatively and quantitatively analyzed using reading center software. The area of CNV lesion components on FA as well as the volume of the neurosensory retina, the outer nuclear layer, subretinal fluid, subretinal hyperreflective material and pigment epithelial detachment (PED) on SDOCT were calculated. VA as well as change in VA from baseline were correlated with all parameters. Results: VA at baseline significantly correlated with final VA as well as change in VA during follow-up. A greater area of total CNV lesion, classic as well as occult CNV lesion components on FA correlated with lower VA during follow-up. Qualitative features that indicated better short-term outcomes included the presence of retinal angiomatous proliferation (RAP) and the absence of cystoid spaces on SDOCT. Eyes with a larger retinal volume demonstrated a greater short-term increase in VA, eyes with larger PED volume and area measurements on OCT demonstrated less VA increase after 12 months. Lower VA outcomes were seen in eyes with larger volume of subretinal hyperreflective material or larger area of PED, as well as lower volume of the outer nuclear layer. No prognostic value could be identified for CNV lesion types other than RAP, subretinal fluid, gender and age. Conclusions: Several FA and SDOCT parameters showed prognostic value for VA outcome after ranibizumab in NVAMD. A larger, prospective dataset will be crucial for defining the relative importance of these parameters.