Clinical phenotypes associated with the complement factor H Y402H variant in age-related macular degeneration

Neovascular age-related macular degeneration: disease pathogenesis and current state of molecular biomarkers predicting treatment response-a scoping review

Age-related macular degeneration is a major cause of blindness, and the development of anti-vascular endothelial growth factor (VEGF) intravitreal treatments has revolutionised the management of the disease. At the same time, new challenges and unmet needs arose due to the limitations of the current therapeutic options. Neovascularisation development during the course of the disease has a complex pathogenetic mechanism, and several biomarkers and their association with treatment outcomes have been investigated. We reviewed the relevant literature about neovascularisation development and biomarkers related to response to treatment. Improving our knowledge on the field can improve patient outcomes and offer personalised care.

Biomarkers as Predictive Factors of Anti-VEGF Response

Age-related macular degeneration is the main cause of irreversible vision in developed countries, and intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections are the current gold standard treatment today. Although anti-VEGF treatment results in important improvements in the course of this disease, there is a considerable number of patients not responding to the standardized protocols. The knowledge of how a patient will respond or how frequently retreatment might be required would be vital in planning treatment schedules, saving both resource utilization and financial costs, but today, there is not an ideal biomarker to use as a predictive response to ranibizumab therapy. Whole blood and blood mononuclear cells are the samples most studied; however, few reports are available on other important biofluid samples for studying this disease, such as aqueous humor. Moreover, the great majority of studies carried out to date were focused on the search for SNPs in genes related to AMD risk factors, but miRNAs, proteomic and metabolomics studies have rarely been conducted in anti-VEGF-treated samples. Here, we propose that genomic, proteomic and/or metabolomic markers could be used not alone but in combination with other methods, such as specific clinic characteristics, to identify patients with a poor response to anti-VEGF treatment to establish patient-specific treatment plans.

Revisiting the role of factor H in age-related macular degeneration: Insights from complement-mediated renal disease and rare genetic variants

Ophthalmologists are long familiar with the eye showing signs of systemic disease, but the association between age-related macular degeneration and abnormal complement activation, common to several renal disorders, has only recently been elucidated. Although complement activation products were identified in drusen almost three decades ago, it was not until the early 21st century that a single-nucleotide polymorphism in the complement factor H gene was identified as a major heritable determinant of age-related macular degeneration, galvanizing global efforts to unravel the pathogenesis of this common disease. Advances in proteomic analyses and familial aggregation studies have revealed distinctive clinical phenotypes segregated by the functional effects of common and rare genetic variants on the mature protein and its splice variant, factor H-like protein 1. The predominance of loss-of-function, N-terminal mutations implicate age-related macular degeneration as a disease of general complement dysregulation, offering several therapeutic avenues for its modulation. Here, we explore the molecular impact of these mutations/polymorphisms on the ability of variant factor H/factor H-like protein 1 to localize to polyanions, pentraxins, proinflammatory triggers, and cell surfaces across ocular and renal tissues and exert its multimodal regulatory functions and their clinical implications. Finally, we critically evaluate key therapeutic and diagnostic efforts in this rapidly evolving field.

Genetic factors associated with response to as-needed aflibercept therapy for typical neovascular age-related macular degeneration and polypoidal choroidal vasculopathy

In the present study, we investigated the association between susceptible genetic variants to age-related macular degeneration (AMD) and response to as-needed intravitreal aflibercept injection (IAI) therapy for exudative AMD including both typical neovascular AMD and polypoidal choroidal vasculopathy (PCV) over 12-months. A total of 234 patients with exudative AMD were initially treated with 3 monthly IAI and thereafter as-needed IAI over 12 months. Seven variants of 6 genes including ARMS2 A69S (rs10490924), CFH (I62V:rs800292 and rs1329428), C2-CFB-SKIV2L(rs429608), C3 (rs2241394), CETP (rs3764261) and ADAMTS-9 (rs6795735) were genotyped for all participants using TaqMan technology. After adjusting for age, gender, baseline BCVA and AMD subtype, A (protective) allele of C2-CFB-SKIV2L rs429608 was associated with visual improvement at 12-month (P = 0.003). Retreatment was associated with T(risk) allele of ARMS2 A69S (P = 2.0 × 10⁻⁴; hazard ratio: 2.18:95%CI: 1.47-3.24) and C(risk) allele of CFH rs1329428 (P = 2.0 × 10⁻³; hazard ratio: 1.74:95%CI: 1.16–2.59) after adjusting for the baseline confounders. The need for additional injections was also associated with T allele of ARMS2 A69S (P = 1.0 × 10⁻⁵) and C allele of CFH rs1329428 (P = 3.0 × 10⁻³) after adjusting for the baseline confounders. The variants of ARMS2 and CFH are informative for both physicians and patients to predict recurrence and to quantify the need for additional injections.

The association between complement factor H rs1061170 polymorphism and age-related macular degeneration: a comprehensive meta-analysis stratified by stage of disease and ethnicity

PURPOSE

The strength of association between complement factor H (CFH) rs1061170 polymorphism and age-related macular degeneration (AMD) differs between AMD subtypes and ethnicities. The main aim was to provide a systematic review and an updated meta-analysis stratified by stage of disease and ethnicity.

METHODS

A literature search in the PubMed-Medline, EMBASE and Web of Science databases was conducted to identify epidemiological studies, published before September 2017, that included at least twp comparison groups (a control group with no signs of AMD and a case group of AMD patients). Genotype distribution, phenotype of the cases, ethnicity, mean age and gender ratio were collected. Odds ratios (ORs) and 95%CIs were estimated under the allelic, homozygous and heterozygous models. Sensitivity and subgroup analyses, by AMD subtype and ethnicity, were performed.

RESULTS

The meta-analysis included data of 27 418 AMD patients and 32 843 controls from 76 studies. In Caucasians, the rs1061170 showed a significant association with early AMD (OR: 1.44; 95%CI 1.27-1.63), dry AMD (OR: 2.90; 95%CI 1.89-4.47) and wet AMD (OR: 2.46; 95%CI 2.15-2.83), under an allelic model. In Asians, the rs1061170 showed a significant association with advanced AMD (OR: 2.09; 95%CI 1.67-2.60), especially wet AMD (OR: 2.24; 95%CI 1.81-2.77).

CONCLUSION

Our work provides a more comprehensive meta-analysis of studies investigating the effect of the CFH rs1061170 polymorphism on AMD risk. These findings not only improve the assessment of disease risk associated with the polymorphism, but also constitute a scientific background to be translated into clinical practice for AMD prevention.

American Journal of Ophthalmology Contributions to Ophthalmic Genetics

PURPOSE

To review the contributions to ophthalmic genetics through the American Journal of Ophthalmology (AJO).

DESIGN

Perspective.

METHODS

A literature search to retrieve original articles, letters, editorials, and published lectures from 1966 to 2017, providing a 50-year review. Titles were excluded that gave no reference to genetics or that presented findings related to a nongenetic ocular condition.

RESULTS

From a search of the Scopus database, 719 articles were ascertained. Of these, 115 were excluded because the title did not reference a genetic condition or have a focus on genetic factors; 4 were excluded because they described animal phenotypes (1966-1967); and 4 were excluded owing to having received no citations up to and including 2015. The highest number of citations was 283 times for a single article on familial aggregation in age-related macular degeneration. The Web of Science database yielded 771 articles; of these, 118 were excluded owing to not reporting human genetic studies; 55 received no citations. The highest number of citations was 307 for a single article, a 1991 paper on Leber hereditary optic neuropathy.

CONCLUSIONS

The Journal's contributions to our understanding of the heritability of human ocular traits have been broad and deep, with international reach. The development of new techniques fostered new concepts and new approaches to rapidly expand the number of known single gene disorders with a defined molecular genetic cause. Reports on Mendelian and complex traits in the AJO abound, along with 6 Edward Jackson Memorial Lectures on retinal dystrophies, Leber congenital amaurosis, age-related macular degeneration, and glaucoma.

Geographic atrophy: Etiopathogenesis and current therapies

Geographic atrophy is characterized by severe visual deficit whose etiology and pathophysiology are yet to be elucidated. As a working hypothesis, oxidative damage could trigger a chronic inflammation in Bruch's membrane-RPE-choriocapillaris complex, mostly due to complement pathway overactivation. Some individuals with mutations in the complement system and other factors have diminished capacity in the modulation of the inflammatory response, which results in cell damage and waste accumulation. This accumulation of intracellular and extracellular waste products manifests as drusen and pigmentary changes that precede the atrophy of photoreceptors, RPE, choriocapillaris with an ischemic process with decreased choroid flow. All these processes can be detected as tomographic findings and autofluorescence signals that are useful in the evaluation of patients with atrophic AMD, which helps to establish an individualized prognosis. Anti-inflammatory, antioxidant and therapies that decrease the accumulation of toxins for the preservation of the RPE cells and photoreceptors are being investigated in order to slow down the progression of this disease.

Incidence and risk factors of retreatment after three-monthly aflibercept therapy for exudative age-related macular degeneration

Though anti-vascular endothelial growth factor therapy has become the standard treatment for exudative age-related macular degeneration (AMD), retreatment after the initial loading injection is inevitable in most eyes with residual or recurrent exudative changes. In the present study, we studied 140 treatment naïve eyes with typical neovascular AMD (n = 71) or polypoidal choroidal vasculopathy (PCV) (n = 69) and investigated the incidence and risk factors of retreatment after 3-monthly intravitreal aflibercept injection for exudative AMD during the 12-month period. At 12 months, best-corrected visual acuity (BCVA) improved significantly from 0.45 ± 0.39 to 0.26 ± 0.33 (P = 4.1 × 10⁻¹¹). Multiple regression analysis revealed that better baseline BCVA (P = 3.6 × 10⁻¹⁴) and thicker subfoveal choroidal thickness (P = 0.039) were associated with better BCVA at 12-months. Retreatment was required in 94 out of 140 (67.1%) eyes. Multivariate logistic regression analysis revealed that older age (P = 7.2 × 10⁻³) and T-allele of ARMS2 A69S (rs10490924) variants (P = 1.9 × 10⁻³) were associated with retreatment. Cox-regression analysis revealed that older age (P = 1.0 × 10⁻²) and T-allele of the ARMS2 gene (P = 6.0 × 10⁻³) were associated with retreatment-free period. The number of retreatment episodes was significantly different among the ARMS2 genotypes (P = 8.1 × 10⁻⁴). These findings might be helpful for physicians when considering the optimal treatment regimen for exudative AMD.

Influence of CFH, HTRA1 and ARMS2 polymorphisms in the response to intravitreal ranibizumab treatment for wet age-related macular degeneration in a Spanish population

AIM

To determine whether gene polymorphisms of the major genetic risk loci for age-related macular degeneration (AMD): ARMS2 (rs10490923), the complement factor H (CFH) (rs1410996) and HTRA1 (rs11200638) influence the response to a treatment regimen with ranibizumab for exudative AMD.

METHODS

This study included 100 patients (100 eyes) with exudative AMD. Patients underwent a treatment with ranibizumab injections monthly during three months. Reinjections were made when the best corrected visual acuity (BCVA) decrease five letters (ETDRS) or central subfield retinal thickness gained 100 µm in optical coherence tomography image. Genotypes (rs10490923, rs1410996 and rs11200638) were analyzed using TaqMan probes or polymerase chain reaction-restricted fragment length polymorphisms analysis.

RESULTS

There were no statistically significant differences in allelic distribution of CFH (rs1410996), ARMS2 (rs10490923) and HTRA1 (rs11200638) polymorphisms regarding to response to ranibizumab treatment.

CONCLUSION

Ranibizumab treatment response is not related to CFH (rs1410996), ARMS2 (rs10490923) and HTRA1 (rs11200638) poymorphisms.

Single-Nucleotide Polymorphisms Associated With Age-Related Macular Degeneration and Lesion Phenotypes in the Comparison of Age-Related Macular Degeneration Treatments Trials

IMPORTANCE

Single-nucleotide polymorphisms (SNPs) associated with the CFH, ARMS2, C3, LIPC, CFB, and C2 genes are associated with age-related macular degeneration (AMD); however, the association of these SNPs with angiographic features of neovascular AMD has been inconsistent in previous studies, and to date, no studies have addressed their association with features on optical coherence tomography.

OBJECTIVE

To evaluate the influence of genotype of SNPs previously associated with AMD on the phenotype of neovascular lesions.

DESIGN, SETTING, AND PARTICIPANTS

Participants for this cross-sectional study were recruited from the 1185 patients enrolled in the Comparison of Age-Related Macular Degeneration Treatments Trials (CATT), a randomized clinical trial. Eligibility criteria for CATT specified that eyes have choroidal neovascularization and visual acuity between 20/25 and 20/320. A subgroup of 835 patients provided blood samples from July 2010 through September 2011 and were genotyped for the SNPs rs1061170 (CFH), rs10490924 (ARMS2),rs2230199 (C3), rs10468017 (LIPC), rs4151667 (CFB), rs547154 (C2) using TaqMan SNP genotyping assays. Data analysis was initiated in November 2013 and completed in January 2016.

MAIN OUTCOMES AND MEASURES

Pretreatment ocular characteristics on fluorescein angiography (lesion type, area of neovascularization and total lesion, retinal angiomatous proliferation) and on time-domain optical coherence tomography (presence of intraretinal, subretinal, and subretinal pigment epithelium fluid; thickness at the foveal center of the retina, subretinal fluid, and subretinal tissue complex), visual acuity, and age.

RESULTS

A total of 835 (73%) of 1150 CATT patients were genotyped. Mean age decreased with the number of risk alleles for CFH (P < .001), ARMS2 (P < .001), and C3 (P = .005). The following results were found as the number of risk alleles increased from 0 to 1 to 2. For CFH, mean total thickness decreased from 476 to 476 to 434 µm (P = .01; adjusted for age, sex, and smoking status). For ARMS2, the mean area of the total lesion increased from 2.0 to 2.8 to 2.4 mm2 (P = .03), the proportion with retinal angiomatous proliferation lesions increased from 8% to 10% to 12% (P = .05), and the proportion with intraretinal fluid increased from 72% to 71% to 82% (P = .008). For C3, the proportion with intraretinal fluid decreased from 78% to 69% to 64% (P = .001), and the mean retinal thickness decreased from 225 to 207 to 197 µm (P = .02).

CONCLUSIONS AND RELEVANCE

CFH, ARMS2, and C3 were associated with specific features of neovascularization at the time patients were enrolled in CATT. Previously identified associations of ARMS2 and CFH with type of choroidal neovascularization on fluorescein angiography were not confirmed. New associations with OCT features identified in CATT need confirmation to establish whether a true association exists.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00593450.

MMP20 and ARMS2/HTRA1 Are Associated with Neovascular Lesion Size in Age-Related Macular Degeneration

PURPOSE

Age-related macular degeneration (AMD) is the leading cause of severe visual impairment. Despite treatment, a central scotoma often remains. The size of the scotoma depends on the lesion size of the choroidal neovascular membrane and significantly affects the patient's quality of life, and the lesion size of neovascularization also affects response to treatments. The aim of this study was to identify genes associated with the neovascular lesion size in neovascular AMD.

DESIGN

A genome-wide association study (GWAS).

PARTICIPANTS

We included 1146 Japanese patients with neovascular AMD.

METHODS

We performed a 2-stage GWAS for the lesion size of AMD as a quantitative trait among 1146 (first stage: 727, second stage: 419) Japanese patients with neovascular AMD. Lesion size was determined by the greatest linear dimension measured with fluorescein angiography examination before treatment. We examined the association between the genotypic distribution of each single nucleotide polymorphism (SNP) and the trait using an additive model adjusted for age and sex. To evaluate the associations between AMD development and SNPs associated with lesion size, we also performed a case-control study by using the genotype data from these 1146 Japanese patients as case subjects and the fixed dataset from the Nagahama Study as control subjects.

MAIN OUTCOME MEASURES

Genes associated with the lesion size in neovascular AMD.

RESULTS

In the discovery stage, rs10895322 in MMP20 showed a genome-wide significant P value of 6.95×10(-8), and rs2284665 in ARMS2/HTRA1 showed a P value of 1.55×10(-7). The associations of these 2 SNPs were successfully replicated in the replication stage, and a meta-analysis of both stages showed genome-wide significant P values (2.80×10(-9) and 4.41×10(-9), respectively). In a case-control study using 3248 Japanese subjects as controls, we could not find contribution of MMP20 rs10895322 for AMD development. Although MMP20 has been thought to be expressed only in dental tissues, we confirmed MMP20 expression in the human retina and retinal pigment epithelium/choroid with polymerase chain reaction.

CONCLUSIONS

The growth of choroidal neovascularization in AMD would be affected by 2 genes: MMP20, a newly confirmed gene expressed in the retina, and ARMS2/HTRA1, a well-known susceptibility gene for AMD.

Complement system activation and endothelial dysfunction in patients with age-related macular degeneration (AMD): possible relationship between AMD and atherosclerosis

Age-related macular degeneration (AMD) shares several pathological and epidemiological similarities with systemic atherosclerosis (AS). First, an association between AS and AMD is apparent from the analyses of the histological and biochemical structure of atherosclerotic plaques in the vascular walls and retinal drusen, the hallmark of AMD. Second, there is considerable evidence implicating endothelial dysfunction in the pathogenesis of both disorders, and cellular oxidative stress appears to be a common denominator underlying this process. Moreover, there are observations that the complement system (CS) triggering inflammatory response contributes to the onset and advancement of both diseases. The CS plays a role in the generation of drusen and neovascularization in AMD as well as in vascular endothelium activation, cell damage and ultimately atherosclerotic plaque formation in the course of systemic arteriosclerosis. It is widely recognized that both AMD and AS are not only related to local stimulation of the CS, but also result in its systemic activation. In addition, a specific Y402H polymorphism of the complement inhibitor factor H has been found to be associated with the incidence of both AMD and AS. Here, we propose a linking hypothesis between CS activation, endothelial dysfunction and the pathogenesis of two common and age-related pathological processes, AS and AMD. We also discuss the potential therapeutic value of pharmacological modulation of CS activation in these disorders.

Genotype-phenotype associations in neovascular age-related macular degeneration

PURPOSE

To examine associations between recognized genetic susceptibility loci and angiographic subphenotypes of the neovascular variant of age-related macular degeneration (nvAMD).

METHODS

Participants (247 nvAMD, 52 early age-related macular degeneration [AMD], and 103 controls) were genotyped (complement factor H and ARMS2/HTRA1). nvAMD participants were assigned to one of two subcategories: mainly classic or mainly occult (based on the proportions of classic and occult choroidal neovascularization). nvAMD and early AMD were reassigned to two groups based on the extent and severity of drusen (retinal pigment epithelium dysfunction or not). Univariate and multivariate analysis were used to examine for associations between participant characteristics and genetic loci after adjusting for age, smoking status, and history of cardiovascular disease.

RESULTS

Univariate analysis confirmed the known significant associations between AMD stage and age, hypertension, and a history of cardiovascular disease. Those with retinal pigment epithelium dysfunction (F = 5.46; P = 0.02) or a positive smoking history (F = 3.89; P = 0.05) were more likely to have been classified as having mainly an occult rather than a mainly classic lesion. Multivariate analysis showed that significant associations were noted with the number of ARMS2/HTRA1 risk alleles (P < 0.001), smoking (ever vs. never) (P = 0.03), and cardiovascular disease (P = 0.01). With early AMD as the reference category, the mainly classic group exhibited significant associations with the number of ARMS2/HTRA1 risk alleles present (P < 0.001) and cardiovascular disease (P = 0.02). When mainly classic was compared with mainly occult, the latter was associated with the ARMS2/HTRA1 locus (P = 0.02).

CONCLUSION

ARMS2/HTRA1 risk genotype may play a role in determining neovascular subphenotype, whereas genetics/demographics, smoking, and systemic health factors contribute to the development of advanced AMD in the presence of early AMD.

Genetic predictors of response to photodynamictherapy

In Western countries, therapeutic management of patients affected by choroidal neovascularization (CNV) secondary to different typologies of macular degeneration represents a major health care problem. Age-related macular degeneration is the disease most frequently associated with CNV development. Schematically, CNVs can be distinguished into classic and occult subtypes, which are characterized by variable natural history and different responsiveness to some therapeutic procedures. At present, the dramatic vision loss due to CNV can be mainly treated by two interventional strategies, which are utilizable in either single or combined modalities: photodynamic therapy with verteporfin (PDT-V), and intravitreal administration of drugs acting against vascular endothelial growth factor. The combined use of PDT-V and anti-angiogenic drugs represents one of the most promising strategies against neovascular macular degeneration, but it unavoidably results in an expensive increase in health resource utilization. However, the positive data from several studies serve as a basis for reconsidering the role of PDT-V, which has undergone a renaissance prompted by the need for a more rational therapeutic approach toward CNV. New pharmacogenetic knowledge of PDT-V points to exploratory prospects to optimize the clinical application of this intriguing photothrombotic procedure. In fact, a Medline search provides data regarding the role of several single nucleotide polymorphisms (SNPs) as genetic predictors of CNV responsiveness to PDT-V. Specifically, correlations between SNPs and different levels of PDT-V efficacy have been detected by examining the gene variants influencing (i) thrombo-coagulative pathways, i.e. methylenetetrahydrofolate reductase (MTHFR) 677C>T (rs1801133), factor V (F5) 1691G>A (rs6025), prothrombin (F2) 20210G>A (rs1799963), and factor XIII-A (F13A1) 185G>T (rs5985); (ii) complement activation and/or inflammatory processes, i.e. complement factor H (CFH) 1277T>C (rs1061170), high-temperature requirement factor A1 (HTRA1) promoter -512G>A (rs11200638), and two variants of the C-reactive protein (CRP) gene (rs2808635 and rs876538); and (iii) production and bioavailability of vascular endothelial growth factor (VEGFA -2578C>A [rs699947] and rs2146323). This article critically evaluates both the clinical plausibility and the opportunity to utilize the most important SNP-response interactions of PDT-V for an effective upgrade of the current anti-CNV therapeutic scenario. In addition, the pharmacogenetics of a very severe post-PDT-V adverse event, i.e. a decrease in acute vision, is briefly discussed. A comprehensive appraisal of the findings reviewed in this article should be carefully considered to design future trials aimed at verifying (after proper genotypic stratification of the enrolled patients) whether these innovative pharmacogenetic approaches will be able to improve the multifaceted interventional management of neovascular macular degeneration.

Age-related macular degeneration and the complement system

Age-related macular degeneration (AMD) is the leading cause of blindness in the developed world. It is a complex multifactorial disease, and despite new advances in treatment, many patients still succumb to visual impairment. The complement pathway has been implicated in the pathogenesis of many diseases, and recently variants in several genes encoding complement pathway proteins have been associated with AMD. Complement proteins have been found in histological specimens of eyes with AMD. Altered levels of both intrinsic complement proteins and activated products have been found in the circulation of patients with AMD. Complement activation may be triggered by oxidative stress, resulting from retinal exposure to incoming light; indeed an inter-play between these two pathological processes seems to exist. Finally, complement inhibitors are currently being evaluated in clinical trials. This article reviews the role of the complement system in AMD, and the potential of complement inhibition in preventing the devastating blindness resulting from this disease.

Genetic factors associated with age-related macular degeneration

Age-related macular degeneration (AMD) is a complex, multifactorial disease associated with environmental and genetic factors. This review emphasizes the clinical impact of the major genetic factors mainly located in the complement factor H gene and on the 10q26 locus, and their current and future implications for the management of AMD.

Complement factor H Y402H gene polymorphism and response to intravitreal bevacizumab in exudative age-related macular degeneration

PURPOSE

To determine whether different complement factor H (CFH) genotypes play a role in treatment of age-related macular degeneration (AMD) with intravitreal bevacizumab.

METHODS

In this prospective study, we included 197 patients with exudative AMD and treated with 1.25 mg intravitreal bevacizumab at 6-week intervals until choroidal neovascularization (CNV) was no longer active. In all patients, ophthalmological examinations, visual acuity, optical coherence tomography (OCT), fundus photography and fluorescein angiography were performed. Single nucleotide polymorphism (SNP) genotyping was performed using restriction fragment length polymorphism (RFLP) analysis of polymerase chain reaction (PCR) products.

RESULTS

Age, gender and baseline mean visual acuity were similar among the three CFH genotypes. There was no significant difference in underlying lesion type of CNV, lesion size, number of injections or macula thickness. When examining the effect of genotype on post-treatment visual acuities, we observed a significant worse outcome for distance and reading visual acuity in the CFH 402HH genotype group. The number of patients who lost 3 or more lines in distance and reading visual acuity testing was significantly higher in the CFH 402HH (41%, 46%) genotype group than in patients with the CFH 402YY (28%, 26%) and CFH 402YH (26%, 24%) genotype.

CONCLUSIONS

In addition to the higher risk for exudative AMD in patients with the CFH 402HH genotype that was found in previous studies, our results show that the CFH 402HH genotype also correlates with lower visual acuity outcome after treatment with bevacizumab, suggesting that pharmacogenetics of CFH plays a role in response to treatment of wet AMD.

Role of complement factor H I62V and age-related maculopathy susceptibility 2 A69S variants in the clinical expression of polypoidal choroidal vasculopathy

PURPOSE

To investigate the role of complement factor H (CFH) I62V (rs800292) and age-related maculopathy susceptibility 2 (ARMS2) A69S (rs10490924) variants in the clinical characteristics of polypoidal choroidal vasculopathy (PCV).

DESIGN

Cross-sectional study.

PARTICIPANTS

A total of 226 Japanese patients with PCV in both eyes (44 cases) or in 1 eye (182 cases).

METHODS

Genotyping was performed in all cases for CFH I62V using TaqMan technology and for ARMS2 A69S by denaturing high-performance chromatography. The incidence of 5 characteristic funduscopic findings was studied, including serous retinal detachment, subretinal hemorrhage, serous pigment epithelial detachment (PED), hemorrhagic PED, and classic choroidal neovascularization (CNV).

MAIN OUTCOME MEASURES

The association of clinical phenotypes, including the incidence of each of 5 specific fundus findings, bilaterality of the disease, and age at onset, with variants of CFH I62V or ARMS2 A69S.

RESULTS

Although there was no association of CFH I62V variants with any of the phenotypes in PCV, at-risk variants of ARMS2 A69S were associated with higher incidences of subretinal hemorrhage, serous PED, and hemorrhagic PED. In particular, the at-risk allele homozygosity of ARMS2 A69S increased the likelihood for hemorrhagic PED by 12.4-fold compared with non-carriers of the allele (confidence interval, 1.60-95.1, P = 0.0001). However, the at-risk allele of ARMS2 A69S was associated with a lower incidence of serous retinal detachment (P = 0.0092). Classic CNV was not associated with either variant. The mean age at the onset of PCV was significantly younger (68.8 years) in those with homozygosity of the at-risk allele of ARMS2 A69S than in those with heterozygosity (71.6 years) or in non-carriers (72.6 years) (P = 0.026). Moreover, the at-risk allele frequencies of the ARMS2 A69S were significantly higher in bilateral cases than in unilateral cases (75.0% vs. 59.3%, P = 0.007).

CONCLUSIONS

ARMS2 A69S variants were significantly associated with hemorrhagic or subpigment epithelium lesions of PCV, and with earlier onset and bilateral involvement. The genotyping of ARMS2 A69S is more informative than that of CFH I62V in understanding the clinical features in patients with PCV.

The significance of the complement system for the pathogenesis of age-related macular degeneration - current evidence and translation into clinical application

BACKGROUND

Dysregulation of the complement system has been shown to play a major role in the pathogenesis of age-related macular degeneration (AMD).

METHODS

The current evidence from human studies derives from immunohistochemical and proteomic studies in donor eyes, genetic association studies, and studies of blood complement protein levels. These lines of evidence are corroborated by in vitro and animal studies.

RESULTS

In AMD donor eyes, detection of complement proteins in drusen suggested local inflammatory processes involving the complement system. Moreover, higher levels of complement proteins in the Bruch's membrane/choroid complex could be detected in AMD donor eyes compared to controls. A large number of independent genetic studies have consistently confirmed the association of AMD with risk or protective variants in genes coding for complement proteins, including complement factor H (CFH), CFH-related proteins 1 and 3, factor B/C2, C3 and factor I. Another set of independent studies detected increased levels of complement activation products in plasma of AMD patients, suggesting that AMD may be a systemic disease and the macula a vulnerable anatomic site of minimal resistance to complement activation. Genotype-phenotype correlations, including the impact of genetic variants on disease progression, gene-environment and pharmacogenetic interactions, have been investigated. There is evidence that complement gene variants may be associated with the progression from early to late forms of AMD, whereas they do not appear to play a significant role when late atrophic AMD has already developed. There are indications for an interaction between genetic variants and supplementation and dietary factors. Also, there is some evidence that variants in the CFH gene influence treatment effects in patients with neovascular AMD.

CONCLUSIONS

Such data suggest that the complement system may have a significant role for developing new prophylactic and therapeutic interventions in AMD. In fact, several compounds acting on the complement pathway are currently in clinical trials. Therapeutics that modulate the complement system need to balance inhibition with preservation of sufficient functional activity in order to maintain adequate immune responses and tissue homeostasis. Specifically, targeting the dysfunction appears more adequate than a global suppression of complement activation in chronic diseases such as AMD.

Inflammatory mediators and angiogenic factors in choroidal neovascularization: pathogenetic interactions and therapeutic implications

Choroidal neovascularization (CNV) is a common and severe complication in heterogeneous diseases affecting the posterior segment of the eye, the most frequent being represented by age-related macular degeneration. Although the term may suggest just a vascular pathological condition, CNV is more properly definable as an aberrant tissue invasion of endothelial and inflammatory cells, in which both angiogenesis and inflammation are involved. Experimental and clinical evidences show that vascular endothelial growth factor is a key signal in promoting angiogenesis. However, many other molecules, distinctive of the inflammatory response, act as neovascular activators in CNV. These include fibroblast growth factor, transforming growth factor, tumor necrosis factor, interleukins, and complement. This paper reviews the role of inflammatory mediators and angiogenic factors in the development of CNV, proposing pathogenetic assumptions of mutual interaction. As an extension of this concept, new therapeutic approaches geared to have an effect on both the vascular and the extravascular components of CNV are discussed.

The role of complement Factor H in age-related macular degeneration: a review

Factor H is a 155kDa sialic acid containing glycoprotein that plays an integral role in the regulation of the complement-mediated immune system that is involved in microbial defense, immune complex processing, and programmed cell death. These events take place primarily in fluid phase and on the cell surface and are particularly important in the context of distinguishing self from non-self. Activation of the complement system occurs within seconds and results in a proteolytic cascade eventually forming the membrane attack complex leading to cell lysis. Factor H protects host cells from injury resulting from unrestrained complement activation. Mutations and SNPs (single nucleotide polymorphisms) in Factor H have been implicated in a variety of human conditions including age-related macular degeneration (AMD), atypical hemolytic uremic syndrome, and membranoproliferative glomuleronephritis type II or dense deposit disease. It should not be surprising that these seemingly unrelated diseases involving mutations in Factor H may share common features. Because the immune process involves, in part, an inflammatory response and common or similar surface antigens, it is also not unexpected to observe features of inflammation, including deposition of bioactive complement fragments such as C3a and C5a, a cellular influx of immune related cells such as lymphocytes, and the potential for multiple organ involvement. We review recent developments in molecular genetics; SNPs, including Y402H; the three-dimensional structure; and mass spectroscopy of Factor H as it relates to the pathogenesis of eye disease. In addition, we discuss the concepts of molecular mimicry, sequestered or hidden antigens, and antigenic cross reactivity, and propose that AMD should not simply be considered to be an eye disease, but rather a systemic vascular disease where the eye has the ability to self regulate a local immune response. Identification of the initial event or inciting antigen has yet to be determined and will significantly advance the understanding of the pathogenesis of AMD.

Comprehensive analysis of complement factor H and LOC387715/ARMS2/HTRA1 variants with respect to phenotype in advanced age-related macular degeneration

PURPOSE

To examine the interaction of genotypic variation of 16 single-nucleotide polymorphisms (SNP) in the complement factor H (CFH) and LOC387715/ARMS2/HTRA1 loci with clinical characteristics of age-related macular degeneration (AMD).

DESIGN

Retrospective cohort study.

METHODS

Eighty-four patients with neovascular AMD were genotyped using direct sequencing or Sequenom iPLEX technology. The Fisher exact test, Cochran-Mantel-Haenszel statistics, and Mann-Whitney U test were used to assess the effect of each SNP with respect to the following phenotypic manifestations: age at diagnosis, gender, affected eye, study and fellow eye visual acuity at diagnosis and at last follow-up, study eye best acuity during follow-up, presence of large drusen and retinal pigment epithelium (RPE) hyperpigmentation in study and fellow eye, choroidal neovascularization (CNV) angiographic subtype (classic vs occult), CNV size, presence of wet AMD in fellow eye, presence of dry AMD in fellow eye, and smoking history.

RESULTS

Only SNPs in the LOC387715/ARMS2/HTRA1 (10q26) region were associated with disease phenotypes. The polymorphisms rs10664316 and rs1049331 were associated with a decreased risk of poor visual acuity during follow-up and at diagnosis; rs2672598 and rs2293870 were associated with a decreased risk of RPE hyperpigmentation; rs10664316 was associated with a decreased risk of RPE hyperpigmentation with large drusen in the study eye, but an increased risk of large drusen in the fellow eye; rs11200638 was associated with an increased risk of larger CNV; rs10490924 and rs11200638 were associated with younger age of diagnosis.

CONCLUSIONS

Several polymorphisms examined in the LOC387715/ARMS2/HTRA1 locus, but none in the CFH region, correlated with specific phenotypic attributes of AMD.

Sequence variants in HTRA1 and LOC387715/ARMS2 and phenotype and response to photodynamic therapy in neovascular age-related macular degeneration in populations from Israel

PURPOSE

Single nucleotide polymorphisms (SNPs) in the tightly linked LOC387715/ARMS2 and HTRA1 genes have been associated with age-related macular degeneration (AMD). We tested whether these SNPs are associated with AMD in Israeli populations, if they underlie variable phenotype and response to therapy in neovascular AMD (NVAMD), and if HTRA1 expression in vivo is associated with its promoter variant.

METHODS

Genotyping for the rs10490924 SNP in LOC387715/ARMS2 and the rs11200638 SNP in HTRA1 was performed on 255 NVAMD patients and 119 unaffected controls from Ashkenazi and Sephardic Jewish, and from Arab origins which are the main ethnic groups composing the Israeli population. Genotyping was correlated with phenotype and response to therapy among 143 patients who underwent photodynamic therapy (PDT). HTRA1 mRNA levels in white blood cells (WBCs), measured by quantitative PCR, were correlated with genotype in 27 participants.

RESULTS

Both SNPs were in almost complete linkage disequilibrium (D'=0.96-1). Homozygotes for the T allele of rs10490924 had an odds ratio (OR) of 8.6, with a 95% confidence interval (CI) of 3.5-20.8, and homozygotes for the A allele of rs11200638 had an OR of 10.7, with a 95% CI of 3.2-35.7, for having AMD (p<0.00001). There was no association among these SNPs and phenotype or response to PDT. HTRA1 mRNA levels in WBCs were not associated with rs11200638 genotypes.

CONCLUSIONS

The rs10490924 SNP in LOC387715/ARMS2 and the rs11200638 SNP in HTRA1 are strongly associated with NVAMD in this Israeli population. These variants do not have a major contribution to the variable phenotype and response to PDT which characterize NVAMD.

Association of complement factor H Y402H polymorphism with phenotype of neovascular age related macular degeneration in Israel

PURPOSE

The Tyr402His variant of complement factor H (CFH) is associated with age-related macular degeneration (AMD) in several populations. Our aim was to evaluate if this single nucleotide polymorphism (SNP) is associated with AMD in the Israeli population and see if it underlies heterogeneity in clinical manifestation and responses to photodynamic therapy (PDT), which characterize neovascular AMD (NVAMD).

METHODS

Genotyping for the Tyr402His variant was performed in 240 NVAMD patients (78.1+/-7 age range) and 118 controls (70.8+/-8.2 age range). Genotyping was correlated with clinical characteristics and treatment parameters in sequential 131 NVAMD patients who underwent PDT.

RESULTS

TheTyr402His coding allele was associated with NVAMD in the Israeli population: odds ratio (OR)=1.9; 95% confidence interval (CI)=1.3-2.6; p=0.0002. Homozygosity for this variant was associated with an OR of 3.4 (95% CI: 1.7-6.8) for having AMD. There was no association among this SNP and age of onset of NVAMD, gender, neovascular lesion size, initial or final visual acuity, and number of PDT sessions required.

CONCLUSIONS

In accordance with findings from the majority of previous study populations, the Tyr402His variant of CFH is associated with NVAMD in Israel. However, heterogeneity in clinical manifestations of NVAMD and in its response to PDT is not underlined by this CFH variant and may be accounted for by other genetic and environmental factors.

[Oxidative stress in association with risk factors for the occurrence and development of age-related macular degeneration]

<zakljucak> Niz rezultata potvrdjuje ulogu oksidativnog stresa u etiopatogenezi AMD i to bilo kao inicijalnog ili izolovanog uzrocnog faktora, ili kao dodatnog cinioca u sklopu drugih faktora rizika. Bolje poznavanje ove oblasti prosiruje mogucnosti prevencije ove, ali i drugih bolesti starijeg zivotnog doba.

[Update on the genetics of age-related macular degeneration]

The relationship between genetics and age-related macular degeneration is well established. Heritability has been estimated to be up to 70%. Recent studies have identified several chromosomal regions that are likely to contain susceptibility loci. Common variations in three genes (CFH, LOC 387715 and C2-FB) strongly influence the risk of age-related macular degeneration. New findings in the field of the genetics of age-related macular degeneration are a starting point toward understanding the causes of AMD and for future therapeutic studies.

Association of complement factor H and LOC387715 genotypes with response of exudative age-related macular degeneration to photodynamic therapy

AIM

To determine whether there is an association between complement factor H (CFH) or LOC387715 genotypes and response to treatment with photodynamic therapy (PDT) for exudative age-related macular degeneration (AMD).

METHODS

Sixty-nine patients being treated for neovascular AMD with PDT were genotyped for the CFH Y402H and LOC387715 A69S polymorphisms by allele-specific digestion of PCR products. AMD phenotypes were characterized by clinical examination, fundus photography, and fluorescein angiography.

RESULTS

Adjusting for age, pre-PDT visual acuity (VA), and lesion type, mean VA after PDT was significantly worse for the CFH TT genotype than for the TC or CC genotypes (P=0.05). Post-PDT VA was significantly worse for the CFH TT genotype in the subgroup of patients with predominantly classic choroidal neovascular lesions (P=0.04), but not for the patients with occult lesions (P=0.22). For the LOC387715 A69S variant, there was no significant difference among the genotypes in response to PDT therapy.

CONCLUSIONS

The CFH Y402H variant was associated with a response to PDT treatment in this study. Patients with the CFH TT genotype fared significantly worse with PDT than did those with the CFH TC and CC genotypes, suggesting a potential relationship between CFH genotype and response to PDT.