Age-related maculopathy: a genomewide scan with continued evidence of susceptibility loci within the 1q31, 10q26, and 17q25 regions

Early SUSVIMO in Neovascular Age-Related Macular Degeneration: Real Word Case Report and Clinical Implications

Purpose

The current standard of care for neovascular age-related macular degeneration is serial vascular endothelial growth factor (VEGF) inhibitor intravitreal injections at varying treatment intervals. SUSVIMO is a port-delivery system of ranibizumab that serves as an alternative, lower-maintenance treatment.

Methods

A case report from a retinal surgery clinic describing the ocular findings, diagnostic workup, and alternative treatment for an 80-year-old man presenting with new-onset neovascular age-related macular degeneration.

Results

Resolved foveal thickness, macular volume, and subretinal fluid after SUSVIMO implantation OD. The patient showed a better response to SUSVIMO than to previous anti-VEGF injections. Before the first refill, the patient began to experience subretinal fluid; however, it was resolved after the refill.

Conclusion

Although effective, real-world management of neovascular age-related macular degeneration is associated with an extensive treatment burden that can compromise treatment adherence. Herein, we describe how the port delivery system (PDS; SUSVIMO) - a refillable ocular implant that can continuously deliver a novel formulation of ranibizumab with refills possible at six months or longer - is a viable early therapy that mitigates the treatment burden of intravitreal injections.

10q26 - The enigma in age-related macular degeneration

Despite comprehensive research efforts over the last decades, the pathomechanisms of age-related macular degeneration (AMD) remain far from being understood. Large-scale genome wide association studies (GWAS) were able to provide a defined set of genetic aberrations which contribute to disease risk, with the strongest contributors mapping to distinct regions on chromosome 1 and 10. While the chromosome 1 locus comprises factors of the complement system with well-known functions, the role of the 10q26-locus in AMD-pathophysiology remains enigmatic. 10q26 harbors a cluster of three functional genes, namely PLEKHA1, ARMS2 and HTRA1, with most of the AMD-associated genetic variants mapping to the latter two genes. High linkage disequilibrium between ARMS2 and HTRA1 has kept association studies from reliably defining the risk-causing gene for long and only very recently the genetic risk region has been narrowed to ARMS2, suggesting that this is the true AMD gene at this locus. However, genetic associations alone do not suffice to prove causality and one or more of the 14 SNPs on this haplotype may be involved in long-range control of gene expression, leaving HTRA1 and PLEKHA1 still suspects in the pathogenic pathway. Both, ARMS2 and HTRA1 have been linked to extracellular matrix homeostasis, yet their exact molecular function as well as their role in AMD pathogenesis remains to be uncovered. The transcriptional regulation of the 10q26 locus adds an additional level of complexity, given, that gene-regulatory as well as epigenetic alterations may influence expression levels from 10q26 in diseased individuals. Here, we provide a comprehensive overview on the 10q26 locus and its three gene products on various levels of biological complexity and discuss current and future research strategies to shed light on one of the remaining enigmatic spots in the AMD landscape.

Is there any association between the frequency of wet age-related macular degeneration recurrences and the seasons of the year?

PURPOSE

To investigate whether a seasonal distribution of the frequency of exudative age-related macular degeneration (wet AMD) recurrences exists.

METHODS

In total, 129 eyes with 171 recurrences in patients suffering from wet AMD were included in the study. All the patients had been treated with intravitreal anti-VEGF injections according to Pro Re Nata treatment regimen. Recurrence was defined as the re-detection of sub-retinal fluid, intraretinal fluid, and/or sub-macular hemorrhage in optical coherence tomography scans, after at least two consecutive monthly examinations with a "dry" macula. The year was divided in three 4-month periods (zone A: June-September, zone B: October-January, and zone C: February-May) based on the weather conditions prevailing in each period. Mean temperature and hours of sunlight exposure were the main weather markers recorded.

RESULTS

Eighty-two recurrences (48%) occurred during the period June-September, 50 (29.2%) during the period October-January, and 39 (22.8%) during the period February-May (Chi-square = 17.5, p < 0.001). Among the groups, neither patients' age (78 ± 8 years A, 76 ± 7 years B, and 79 ± 8 years C, p = 0.15) nor gender status (40% men A, 36% men B, and 51% men C, p = 0.35) differed significantly. Mean temperature was 27.6 ± 1.8 °C, 15.1 ± 4.6 °C, and 16.5 ± 4.4 °C in zones A, B, and C, respectively. Hours (h) of sunlight exposure (average hours/month) were 344 ± 34 h, 188 ± 42 h, and 223 ± 57 h in zones A, B, and C.

CONCLUSION

We demonstrated that the frequency of wet AMD recurrences is significantly elevated during the warmer months, possibly due to the higher levels of UV radiation and mean temperature. Further research is necessary to validate our findings.

Polypoidal Choroidal Vasculopathy: Updates on Risk Factors, Diagnosis, and Treatments

There have been recent advances in basic research and clinical studies in polypoidal choroidal vasculopathy (PCV). A recent, large-scale, population-based study found systemic factors, such as male gender and smoking, were associated with PCV, and a recent systematic review reported plasma C-reactive protein, a systemic biomarker, was associated with PCV. Growing evidence points to an association between pachydrusen, recently proposed extracellular deposits associated with the thick choroid, and the risk of development of PCV. Many recent studies on diagnosis of PCV have focused on applying criteria from noninvasive multimodal retinal imaging without requirement of indocyanine green angiography. There have been attempts to develop deep learning models, a recent subset of artificial intelligence, for detecting PCV from different types of retinal imaging modality. Some of these deep learning models were found to have high performance when they were trained and tested on color retinal images with corresponding images from optical coherence tomography. The treatment of PCV is either a combination therapy using verteporfin photodynamic therapy and anti-vascular endothelial growth factor (VEGF), or anti-VEGF monotherapy, often used with a treat-and-extend regimen. New anti-VEGF agents may provide more durable treatment with similar efficacy, compared with existing anti-VEGF agents. It is not known if they can induce greater closure of polypoidal lesions, in which case, combination therapy may still be a mainstay. Recent evidence supports long-term follow-up of patients with PCV after treatment for early detection of recurrence, particularly in patients with incomplete closure of polypoidal lesions.

Lifestyle Intervention Randomized Controlled Trial for Age-Related Macular Degeneration (AMD-Life): Study Design

Age-related macular degeneration (AMD) has a strong genetic basis, but environmental factors such as smoking and a healthy diet can decrease the genetic fate by up to 50%. Current guidelines for clinical management include recommendations for a healthy lifestyle and antioxidant supplementation. However, many ophthalmologists do not inform their patients of this AMD-beneficial lifestyle. An important reason is the lack of trust that transition of lifestyle will be feasible in persons of advanced age and lack of methodology to measure lifestyle or its biological effects. To address these issues, we set up the lifestyle intervention study AMD-Life. It aims to investigate whether personalized risk-profiling (including genetic testing) and/or additional coaching can motivate patients to change their lifestyle. It also explores which biomarkers best reflect lifestyle change beneficial for AMD. The first year is a three-arm, self-contained open-label randomized clinical trial. A total of 150 AMD patients aged 55-85 years were randomized into three arms: (A) merely standard recommendations; (B) A conditions plus personalized risk profiling based on genetics and lifestyle, (C) B conditions plus coaching. The second year tests sustainability of lifestyle changes without active intervention. AMD-Life can provide further insight into the relevance of these interventions for the clinical management of AMD.

Molecular Genetic Mechanisms in Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is among the leading causes of irreversible blindness worldwide. In addition to environmental risk factors, such as tobacco use and diet, genetic background has long been established as a major risk factor for the development of AMD. However, our ability to predict disease risk and personalize treatment remains limited by our nascent understanding of the molecular mechanisms underlying AMD pathogenesis. Research into the molecular genetics of AMD over the past two decades has uncovered 52 independent gene variants and 34 independent loci that are implicated in the development of AMD, accounting for over half of the genetic risk. This research has helped delineate at least five major pathways that may be disrupted in the pathogenesis of AMD: the complement system, extracellular matrix remodeling, lipid metabolism, angiogenesis, and oxidative stress response. This review surveys our current understanding of each of these disease mechanisms, in turn, along with their associated pathogenic gene variants. Continued research into the molecular genetics of AMD holds great promise for the development of precision-targeted, personalized therapies that bring us closer to a cure for this debilitating disease.

Ongoing controversies and recent insights of the ARMS2-HTRA1 locus in age-related macular degeneration

Age-related macular degeneration (AMD) is the most common cause of central vision loss among elderly populations in industrialized countries. Genome-wide association studies have consistently associated two genomic loci with progression to late-stage AMD: the complement factor H (CFH) locus on chromosome 1q31 and the age-related maculopathy susceptibility 2-HtrA serine peptidase 1 (ARMS2-HTRA1) locus on chromosome 10q26. While the CFH risk variant has been shown to alter complement activity, the ARMS2-HTRA1 risk haplotype remains enigmatic due to high linkage disequilibrium and inconsistent functional findings spanning two genes that are plausibly causative for AMD risk. In this review, we detail the genetic and functional evidence used to support either ARMS2 or HTRA1 as the causal gene for AMD risk, emphasizing both the historical development and the current understanding of the ARMS2-HTRA1 locus in AMD pathogenesis. We conclude by summarizing the evidence in favor of HTRA1 and present our hypothesis whereby HTRA1-derived ECM fragments mediate AMD pathogenesis.

A Systematic Review of Carotenoids in the Management of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) remains a leading cause of modifiable vision loss in older adults. Chronic oxidative injury and compromised antioxidant defenses represent essential drivers in the development of retinal neurodegeneration. Overwhelming free radical species formation results in mitochondrial dysfunction, as well as cellular and metabolic imbalance, which becomes exacerbated with increasing age. Thus, the depletion of systemic antioxidant capacity further proliferates oxidative stress in AMD-affected eyes, resulting in loss of photoreceptors, neuroinflammation, and ultimately atrophy within the retinal tissue. The aim of this systematic review is to examine the neuroprotective potential of the xanthophyll carotenoids lutein, zeaxanthin, and meso-zeaxanthin on retinal neurodegeneration for the purpose of adjunctive nutraceutical strategy in the management of AMD. A comprehensive literature review was performed to retrieve 55 eligible publications, using four database searches from PubMed, Embase, Cochrane Library, and the Web of Science. Epidemiology studies indicated an enhanced risk reduction against late AMD with greater dietary consumption of carotenoids, meanwhile greater concentrations in macular pigment demonstrated significant improvements in visual function among AMD patients. Collectively, evidence strongly suggests that carotenoid vitamin therapies offer remarkable synergic protection in the neurosensory retina, with the potential to serve as adjunctive nutraceutical therapy in the management of established AMD, albeit these benefits may vary among different stages of disease.

Differential and Altered Spatial Distribution of Complement Expression in Age-Related Macular Degeneration

Purpose

Dysregulation of the alternative complement pathway is a major pathogenic mechanism in age-related macular degeneration. We investigated whether locally synthesized complement components contribute to AMD by profiling complement expression in postmortem eyes with and without AMD.

Methods

AMD severity grade 1 to 4 was determined by analysis of postmortem acquired fundus images and hematoxylin and eosin stained histological sections. TaqMan (donor eyes n = 39) and RNAscope/in situ hybridization (n = 10) were performed to detect complement mRNA. Meso scale discovery assay and Western blot (n = 31) were used to measure complement protein levels.

Results

The levels of complement mRNA and protein expression were approximately 15- to 100-fold (P < 0.0001-0.001) higher in macular retinal pigment epithelium (RPE)/choroid tissue than in neural retina, regardless of AMD grade status. Complement mRNA and protein levels were modestly elevated in vitreous and the macular neural retina in eyes with geographic atrophy (GA), but not in eyes with early or intermediate AMD, compared to normal eyes. Alternative and classical pathway complement mRNAs (C3, CFB, CFH, CFI, C1QA) identified by RNAscope were conspicuous in areas of atrophy; in those areas C3 mRNA was observed in a subset of IBA1+ microglia or macrophages.

Conclusions

We verified that RPE/choroid contains most ocular complement; thus RPE/choroid rather than the neural retina or vitreous is likely to be the key site for complement inhibition to treat GA or earlier stage of the disease. Outer retinal local production of complement mRNAs along with evidence of increased complement activation is a feature of GA.

Associations between the Complement System and Choroidal Neovascularization in Wet Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of blindness affecting the elderly in the Western world. The most severe form of AMD, wet AMD (wAMD), is characterized by choroidal neovascularization (CNV) and acute vision loss. The current treatment for these patients comprises monthly intravitreal injections of anti-vascular endothelial growth factor (VEGF) antibodies, but this treatment is expensive, uncomfortable for the patient, and only effective in some individuals. AMD is a complex disease that has strong associations with the complement system. All three initiating complement pathways may be relevant in CNV formation, but most evidence indicates a major role for the alternative pathway (AP) and for the terminal complement complex, as well as certain complement peptides generated upon complement activation. Since the complement system is associated with AMD and CNV, a complement inhibitor may be a therapeutic option for patients with wAMD. The aim of this review is to (i) reflect on the possible complement targets in the context of wAMD pathology, (ii) investigate the results of prior clinical trials with complement inhibitors for wAMD patients, and (iii) outline important considerations when developing a future strategy for the treatment of wAMD.

Age-related Macular Degeneration: Nutrition, Genes and Deep Learning-The LXXVI Edward Jackson Memorial Lecture

PURPOSE

To evaluate the importance of nutritional supplements, dietary pattern, and genetic associations in age-related macular degeneration (AMD); and to discuss the technique of artificial intelligence/deep learning to potentially enhance research in detecting and classifying AMD.

DESIGN

Retrospective literature review.

METHODS

To review the studies of both prospective and retrospective (post hoc) analyses of nutrition, genetic variants, and deep learning in AMD in both the Age-Related Eye Disease Study (AREDS) and AREDS2.

RESULTS

In addition to demonstrating the beneficial effects of the AREDS and AREDS2 supplements of antioxidant vitamins and zinc (plus copper) for reducing the risk of progression to late AMD, these 2 studies also confirmed the importance of high adherence to Mediterranean diet in reducing progression of AMD in persons with varying severity of disease. In persons with the protective genetic alleles of complement factor H (CFH), the Mediterranean diet had further beneficial effect. However, despite the genetic association with AMD progression, prediction models found genetic information added little to the high predictive value of baseline severity of AMD for disease progression. The technique of deep learning, an arm of artificial intelligence, using color fundus photographs from AREDS/AREDS2 was superior in some cases and noninferior in others to clinical human grading (retinal specialists) and to the gold standard of the certified reading center graders.

CONCLUSIONS

Counseling individuals affected with AMD regarding the use of the AREDS2 supplements and the beneficial association of the Mediterranean diet is an important public health message. Although genetic testing is important in research, it is not recommended for prediction of disease or to guide therapies and/or dietary interventions in AMD. Techniques in deep learning hold great promise, but further prospective research is required to validate the use of this technique to provide improvement in accuracy and sensitivity/specificity in clinical research and medical management of patients with AMD.

Gene-Based Association Testing of Dichotomous Traits With Generalized Functional Linear Mixed Models Using Extended Pedigrees: Applications to Age-Related Macular Degeneration

Genetics plays a role in age-related macular degeneration (AMD), a common cause of blindness in the elderly. There is a need for powerful methods for carrying out region-based association tests between a dichotomous trait like AMD and genetic variants on family data. Here, we apply our new generalized functional linear mixed models (GFLMM) developed to test for gene-based association in a set of AMD families. Using common and rare variants, we observe significant association with two known AMD genes: CFH and ARMS2. Using rare variants, we find suggestive signals in four genes: ASAH1, CLEC6A, TMEM63C, and SGSM1. Intriguingly, ASAH1 is down-regulated in AMD aqueous humor, and ASAH1 deficiency leads to retinal inflammation and increased vulnerability to oxidative stress. These findings were made possible by our GFLMM which model the effect of a major gene as a fixed mean, the polygenic contributions as a random variation, and the correlation of pedigree members by kinship coefficients. Simulations indicate that the GFLMM likelihood ratio tests (LRTs) accurately control the Type I error rates. The LRTs have similar or higher power than existing retrospective kernel and burden statistics. Our GFLMM-based statistics provide a new tool for conducting family-based genetic studies of complex diseases. Supplementary materials for this article, including a standardized description of the materials available for reproducing the work, are available as an online supplement.

Genetic Association of Age-Related Macular Degeneration and Polypoidal Choroidal Vasculopathy

Age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV) are leading causes of irreversible blindness among the elderly population in developed countries. Although being considered as different subtypes of a same disease, neovascular AMD and PCV have differences in clinical, epidemiological, therapeutic, and genetic profiles. Both AMD and PCV are complex diseases involving multiple genetic and environmental risk factors. Different genetic strategies have been adopted to discover associated genes and variants for neovascular AMD and PCV, including genome-wide association study (GWAS), next-generation sequencing (NGS) based sequence analysis, and candidate gene analyses. So far, a number of susceptible genes have been identified for AMD and/or PCV, such as CFH, ARMS2-HTRA1, C2-CFB-SKIV2L, C3, CETP, and FGD6. Although many of these genes are shared by AMD and PCV, some showed difference between them, such as ARMS2-HTRA1 and FGD6. Also, some of the genes showed ethnic diversities, such as the CFH p.Tyr402His variant. Further larger-scale genomic studies should be warranted to identify more susceptibility genes for AMD and, in particular, PCV among different populations, and differentiate the genetic architectures between neovascular AMD and PCV.

Predictive genetics for AMD: Hype and hopes for genetics-based strategies for treatment and prevention

Age-related macular degeneration (AMD) is a complex disease with multiple genetic and environmental risk factors. In the age of molecular genetics, many investigators have established a link between genes and development or progression of the disease. This later evolved to determine whether phenotypic features of AMD have distinct genetic profiles. Molecular genetics have subsequently been introduced as factors in risk assessment models, increasing the predictive value of these tools. Models seek to predict either development or progression of disease, and different AMD-related genes aid our understanding of these respective features. Several investigators have attempted to link molecular genetics with treatment response, but results and their clinical significance vary. Ocular and systemic biomarkers may interact with established genes, promising future routes of ongoing clinical assessment. Our understanding of AMD molecular genetics is not yet sufficient to recommend routine testing, despite its utility in the research setting. Clinicians must be wary of misusing population-based risk models from genetic and biomarker associations, as they are not necessarily relevant for individual counseling. This review addresses the known uses of predictive genetics, and suggests future directions.

Molecular Mechanisms of Complement System Proteins and Matrix Metalloproteinases in the Pathogenesis of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is an eye disorder affecting predominantly the older people above the age of 50 years in which the macular region of the retina deteriorates, resulting in the loss of central vision. The key factors associated with the pathogenesis of AMD are age, smoking, dietary, and genetic risk factors. There are few associated and plausible genes involved in AMD pathogenesis. Common genetic variants (with a minor allele frequency of >5% in the population) near the complement genes explain 40-60% of the heritability of AMD. The complement system is a group of proteins that work together to destroy foreign invaders, trigger inflammation, and remove debris from cells and tissues. Genetic changes in and around several complement system genes, including the CFH, contribute to the formation of drusen and progression of AMD. Similarly, Matrix metalloproteinases (MMPs) that are normally involved in tissue remodeling also play a critical role in the pathogenesis of AMD. MMPs are involved in the degradation of cell debris and lipid deposits beneath retina but with age their functions get affected and result in the drusen formation, succeeding to macular degeneration. In this review, AMD pathology, existing knowledge about the normal and pathological role of complement system proteins and MMPs in the eye is reviewed. The scattered data of complement system proteins, MMPs, drusenogenesis, and lipofusogenesis have been gathered and discussed in detail. This might add new dimensions to the understanding of molecular mechanisms of AMD pathophysiology and might help in finding new therapeutic options for AMD.

Big DNA as a tool to dissect an age-related macular degeneration-associated haplotype

Age-related Macular Degeneration (AMD) is a leading cause of blindness in the developed world, especially in aging populations, and is therefore an important target for new therapeutic development. Recently, there have been several studies demonstrating strong associations between AMD and sites of heritable genetic variation at multiple loci, including a highly significant association at 10q26. The 10q26 risk region contains two genes, HTRA1 and ARMS2, both of which have been separately implicated as causative for the disease, as well as dozens of sites of non-coding variation. To date, no studies have successfully pinpointed which of these variant sites are functional in AMD, nor definitively identified which genes in the region are targets of such regulatory variation. In order to efficiently decipher which sites are functional in AMD phenotypes, we describe a general framework for combinatorial assembly of large ‘synthetic haplotypes’ along with delivery to relevant disease cell types for downstream functional analysis. We demonstrate the successful and highly efficient assembly of a first-draft 119kb wild-type ‘assemblon’ covering the HTRA1/ARMS2 risk region. We further propose the parallelized assembly of a library of combinatorial variant synthetic haplotypes covering the region, delivery and analysis of which will identify functional sites and their effects, leading to an improved understanding of AMD development. We anticipate that the methodology proposed here is highly generalizable towards the difficult problem of identifying truly functional variants from those discovered via GWAS or other genetic association studies.

Genomic and Phenomic Research in the 21st Century

The field of human genomics has changed dramatically over time. Initial genomic studies were predominantly restricted to rare disorders in small families. Over the past decade, researchers changed course from family-based studies and instead focused on common diseases and traits in populations of unrelated individuals. With further advancements in biobanking, computer science, electronic health record (EHR) data, and more affordable high-throughput genomics, we are experiencing a new paradigm in human genomic research. Rapidly changing technologies and resources now make it possible to study thousands of diseases simultaneously at the genomic level. This review will focus on these advancements as scientists begin to incorporate phenome-wide strategies in human genomic research to understand the etiology of human diseases and develop new drugs to treat them.

Association of risk genotypes of ARMS2/LOC387715 A69S and CFH Y402H with age-related macular degeneration with and without reticular pseudodrusen: a meta-analysis

To pool the results of published data regarding association of ARMS2/LOC387715 A69S, CFH Y402H and CFH I62V genotypes with age-related macular degeneration (AMD) with and without reticular pseudodrusen (RPD). The results of this pooled data used to estimate the contribution of each of these genes in the pathogenesis of RPD. Heterogeneity of studies was evaluated using Cochran Q-test and I² index. To modify the heterogeneity in the variables, we used the random effects model. Meta-analysis was performed using STATA. Odds ratio (OR) of genotypes in each study was calculated. Six studies of AMD with RPD and AMD without RPD cases included in this analysis. Analysis of pooled data showed that risk genotypes frequency of ARMS2 A69S was significantly different between AMD with RPD and AMD without RPD [OR = 1.82, 95% confidence interval (CI): 1.26-2.63 for GT versus GG ARMS2 A69S; OR = 2.40, 95% CI: 1.50-3.84 for TT versus GG ARMS2 A69S]. Further analysis also showed that the risk genotype frequency of CFH Y402H was not significantly different between these two groups (OR = 1.02, 95% CI: 0.69-1.50 for CT versus TT CFH Y402H; OR = 1.09, 95% CI: 0.74-1.60 for CC versus TT CFH Y402H). Comparison of above-mentioned ORs revealed statistically higher values for GT and TT genotypes of ARMS2 A69S compared with CFH Y402H genotypes (p = 0.011, p = 0.014, respectively).Our analysis showed stronger contribution of ARMS2 in AMD with RPD group versus AMD without RPD group, in comparison with CFH genotypes.

Complement factor H in AMD: Bridging genetic associations and pathobiology

Age-Related Macular Degeneration (AMD) is a complex multifactorial disease characterized in its early stages by lipoprotein accumulations in Bruch's Membrane (BrM), seen on fundoscopic exam as drusen, and in its late forms by neovascularization ("wet") or geographic atrophy of the Retinal Pigmented Epithelial (RPE) cell layer ("dry"). Genetic studies have strongly supported a relationship between the alternative complement cascade, in particular the common H402 variant in Complement Factor H (CFH) and development of AMD. However, the functional significance of the CFH Y402H polymorphism remains elusive. In this article, we critically review the literature surrounding the functional significance of this polymorphism. Furthermore, based on our group's studies we propose a model in which CFH H402 affects CFH binding to heparan sulfate proteoglycans leading to accelerated lipoprotein accumulation in BrM and drusen progression. We also review the literature on the role of other complement components in AMD pathobiologies, including C3a, C5a and the membrane attack complex (MAC), and on transgenic mouse models developed to interrogate in vivo the effects of the CFH Y402H polymorphism.

Association of human height-related genetic variants with familial short stature in Han Chinese in Taiwan

Human height can be described as a classical and inherited trait model. Genome-wide association studies (GWAS) have revealed susceptible loci and provided insights into the polygenic nature of human height. Familial short stature (FSS) represents a suitable trait for investigating short stature genetics because disease associations with short stature have been ruled out in this case. In addition, FSS is caused only by genetically inherited factors. In this study, we explored the correlations of FSS risk with the genetic loci associated with human height in previous GWAS, alone and cumulatively. We systematically evaluated 34 known human height single nucleotide polymorphisms (SNPs) in relation to FSS in the additive model (p < 0.00005). A cumulative effect was observed: the odds ratios gradually increased with increasing genetic risk score quartiles (p < 0.001; Cochran-Armitage trend test). Six affected genes-ZBTB38, ZNF638, LCORL, CABLES1, CDK10, and TSEN15-are located in the nucleus and have been implicated in embryonic, organismal, and tissue development. In conclusion, our study suggests that 13 human height GWAS-identified SNPs are associated with FSS risk both alone and cumulatively.

Systematic Functional Testing of Rare Variants: Contributions of CFI to Age-Related Macular Degeneration

Purpose

Genome-wide association (GWAS) and sequencing studies for AMD have highlighted the importance of coding variants at loci that encode components of the complement pathway. However, assessing the contribution of such alleles to AMD, especially when they are rare, remains coarse, in part because of the persistent challenge in establishing their functional relevance. Others and we have shown previously that rare alleles in complement factor I (CFI) can be tested functionally using a surrogate in vivo assay of retinal vascularization in zebrafish embryos. Here, we have implemented and scaled these tools to assess the overall contribution of rare alleles in CFI to AMD.

Methods

We performed targeted sequencing of CFI in 731 AMD patients, followed by replication in a second patient cohort of 511 older healthy individuals. Systematic functional testing of all alleles and post-hoc statistical analysis of functional variants was also performed.

Results

We discovered 20 rare coding nonsynonymous variants, including the previously reported G119R allele. In vivo testing led to the identification of nine variants that alter CFI; six of which are associated with hypoactive complement factor I (FI). Post-hoc analysis in ethnically matched, population controls showed six of these to be present exclusively in cases.

Conclusions

Taken together, our data argue that multiple rare and ultra-rare alleles in CFI contribute to AMD pathogenesis; they improve the precision of the assessment of the contribution of CFI to AMD; and they offer a rational route to establishing both causality and direction of allele effect for genes associated with this disorder.

Genetic risk models: Influence of model size on risk estimates and precision

Disease risk estimation plays an important role in disease prevention. Many studies have found that the ability to predict risk improves as the number of risk single-nucleotide polymorphisms (SNPs) in the risk model increases. However, the width of the confidence interval of the risk estimate is often not considered in the evaluation of the risk model. Here, we explore how the risk and the confidence interval width change as more SNPs are added to the model in the order of decreasing effect size, using both simulated data and real data from studies of abdominal aortic aneurysms and age-related macular degeneration. Our results show that confidence interval width is positively correlated with model size and the majority of the bigger models have wider confidence interval widths than smaller models. Once the model size is bigger than a certain level, the risk does not shift markedly, as 100% of the risk estimates of the one-SNP-bigger models lie inside the confidence interval of the one-SNP-smaller models. We also created a confidence interval-augmented reclassification table. It shows that both more effective SNPs with larger odds ratios and less effective SNPs with smaller odds ratios contribute to the correct decision of whom to screen. The best screening strategy is selected and evaluated by the net benefit quantity and the reclassification rate. We suggest that individuals whose upper bound of their risk confidence interval is above the screening threshold, which corresponds to the population prevalence of the disease, should be screened.

Association of ARMS2/LOC387715 A69S, CFH Y402H, and CFH I62V polymorphisms with retinal angiomatous proliferation compared with typical age-related macular degeneration: a meta-analysis

PURPOSE

To compare the published results of studies on the genotype association of ARMS2/LOC387715 A69S, CFH Y402H, and CFH I62V in cases diagnosed as retinal angiomatous proliferation (RAP) versus neovascular age-related macular degeneration (AMD) or healthy controls.

METHODS

Heterogeneity of studies was evaluated using Cochran's Q test and I-square index. To modify the heterogeneity in the variables, we used random effects model. Meta-analysis was performed using STATA.

RESULTS

Four studies were included with 1076 neovascular AMD patients, 222 RAP cases, and 2276 control subjects. Pooled overall odds ratios for RAP/AMD were 1.15 (95% CI 0.60-2.18) for GT versus GG, 3.52 (95% CI 1.25-9.91) for TT versus GG ARMS2, 0.98 (95% CI 0.22-4.29) for GA versus AA, 1.00 (95% CI 0.25-4.02) for GG versus AA CFHI62V, 0.57 (95% CI 0.35-0.93) for CT versus TT CFH Y402H, and 0.40 (95% CI 0.22-0.74) for CC versus TT CFH Y402H. Regression analysis showed that ARMS2 TT genotype has a statistically significant effect on RAP versus AMD compared to CFH genotypes (P < 0.001).

CONCLUSION

This meta-analysis disclosed a stronger effect of ARMS2 genotypes in RAP cases compared with CFH Y402H and I62V genotypes.

The complement system in age-related macular degeneration: A review of rare genetic variants and implications for personalized treatment

•

The complement system plays a central role in age-related macular degeneration (AMD).

•

Common and rare genetic variants in complement genes have been identified in AMD.

•

Several of the rare variants affect the functioning of the complement system.

•

However, a genetic association with AMD cannot always be proven.

•

Functional assays can help identify patients for complement inhibiting therapies.

Age-related macular degeneration (AMD) is a progressive retinal disease and the major cause of irreversible vision loss in the elderly. Numerous studies have found both common and rare genetic variants in the complement pathway to play a role in the pathogenesis of AMD. In this review we provide an overview of rare variants identified in AMD patients, and summarize the functional consequences of rare genetic variation in complement genes on the complement system. Finally, we discuss the relevance of this work in light of ongoing clinical trials that study the effectiveness of complement inhibitors against AMD.

Lipids, oxidized lipids, oxidation-specific epitopes, and Age-related Macular Degeneration

Age-related Macular Degeneration (AMD) is the leading cause of blindness among the elderly in western societies. While antioxidant micronutrient treatment is available for intermediate non-neovascular disease, and effective anti-vascular endothelial growth factor treatment is available for neovascular disease, treatment for early AMD is lacking due to an incomplete understanding of the early molecular events. The role of lipids, which accumulate in the macula, and their oxidation, has emerged as an important factor in disease development. These oxidized lipids can either directly contribute to tissue injury or react with amine on proteins to form oxidation-specific epitopes, which can induce an innate immune response. If inadequately neutralized, the inflammatory response from these epitopes can incite tissue injury during disease development. This review explores how the accumulation of lipids, their oxidation, and the ensuing inflammatory response might contribute to the pathogenesis of AMD. This article is part of a Special Issue entitled: Lipid modification and lipid peroxidation products in innate immunity and inflammation edited by Christoph J. Binder .

CFH Y402H and VEGF Polymorphisms and Anti-VEGF Treatment Response in Exudative Age-Related Macular Degeneration

PURPOSE

The aim of this study was to evaluate the prevalence of single nucleotide polymorphisms (SNPs) in complement factor H (CFH) Y402H and VEGF rs2146323 and rs699947 in exudative age-related macular degeneration (AMD) and their relationship with intravitreal anti-VEGF treatment response.

METHODS

A total of 109 exudative AMD patients and 70 controls were included. Patients were classified as 'good responders' and 'nonresponders' based on the changes in best corrected visual acuity, central foveal thickness, lesion size, and the persistence of retinal hemorrhage after three dosages of anti-VEGF. We examined CFH, VEGF rs2146323 and rs699947 SNPs, and plasma interleukin-6 (IL-6) levels in both groups.

RESULTS

In total, 42 patients (38.5%) and 11 controls (15.7%) had homozygote wild genotype TT (p = 0.002). The variant C allele frequency was 45% in controls and 31.7% in patients (p = 0.011). A and C allele frequencies for VEGF rs699947 and rs2416323 were similar between the control and patient groups (p = 0.947, p = 0.378). Both SNPs were similar in responders and nonresponders. No significant difference was detected between plasma IL-6 levels of the control and AMD groups (p = 0.594), but the levels were higher in good responders than nonresponders (p < 0.001).

CONCLUSION

CFH Y402H SNP might be protective for AMD in the Turkish population. VEGF rs2146323 and rs699947 SNPs have no relationship to exudative AMD formation, and none of these seem to have any effect on anti-VEGF response.

Age-Related Macular Degeneration: Genetics and Biology

Age-related macular degeneration (AMD), widely prevalent across the globe, is a major stakeholder among adult visual morbidity and blindness, not only in the Western world but also in Asia. Several risk factors have been identified, including critical genetic factors, which were never imagined 2 decades ago. The etiopathogenesis is emerging to demonstrate that immune and complement-related inflammation pathway members chronically exposed to environmental insults could justifiably influence disease morbidity and treatment outcomes. Approximately half a dozen physiological and biochemical cascades are disrupted in the AMD disease genesis, eventually leading to the distortion and disruption of the subretinal space, subretinal pigment epithelium, and Bruch membrane, thus setting off chaos and disorder for signs and symptoms to manifest. Approximately 3 dozen genetic factors have so far been identified, including the recent ones, through powerful genomic technologies and large robust sample sizes. The noteworthy genetic variants (common and rare) are complement factor H, complement factor H-related genes 1 to 5, C3, C9, ARMS2/HTRA1, vascular endothelial growth factor A, vascular endothelial growth factor receptor 2/KDR, and rare variants (show causal link) such as TIMP3, fibrillin, COL4A3, MMP19, and MMP9. Despite the enormous amount of scientific information generated over the years, diagnostic genetic or biomarker tests are still not available for clinicians to understand the natural course of the disease and its management in a patient. However, further research in the field should reduce this gap not only by aiding the clinician but also through the possibilities of clinical intervention with complement pathway-related inhibitors entering preclinical and clinical trials in the near future.

AMD and the alternative complement pathway: genetics and functional implications

Age-related macular degeneration (AMD) is an ocular neurodegenerative disorder and is the leading cause of legal blindness in Western societies, with a prevalence of up to 8 % over the age of 60, which continues to increase with age. AMD is characterized by the progressive breakdown of the macula (the central region of the retina), resulting in the loss of central vision including visual acuity. While its molecular etiology remains unclear, advances in genetics and genomics have illuminated the genetic architecture of the disease and have generated attractive pathomechanistic hypotheses. Here, we review the genetic architecture of AMD, considering the contribution of both common and rare alleles to susceptibility, and we explore the possible mechanistic links between photoreceptor degeneration and the alternative complement pathway, a cascade that has emerged as the most potent genetic driver of this disorder.

Association of Combined Complement Factor H Y402H and ARMS/LOC387715 A69S Polymorphisms with Age-related Macular Degeneration: A Meta-analysis

PURPOSE

Complement factor H (CFH) Y402H (rs1061170) and age-related maculopathy susceptibility2 (ARMS2)/LOC387715 A69S (rs10490924) polymorphisms shown to have significant association with age-related macular degeneration (AMD). In this meta-analysis, we pooled the results of the available association studies between combined ARMS2/LOC387715A69S-CFHY402H genotypes and AMD to estimate the possible synergistic or multiplicative effects.

METHODS

Heterogeneity of studies was evaluated using the Cochran Q-test and the I-square index. To modify the heterogeneity in the variables, we used random effects model. Meta-analysis was performed using STATA. To estimate the additive or supra-additive effects, we calculated relative excess risk due to interaction (RERI), attributable proportion due to interaction (AP), synergy index (S), and multiplicative index (V).

RESULTS

We included eight studies with 2915 AMD patients and 3505 control subjects. Considering the GGTT genotypes as reference lines, the pooled AMD Odds Ratios for stratified combined genotypes were 2.32 (95% CI 1.64-3.28) for GGnon-TT, 2.49 (95% CI 1.72-3.60) for non-GGTT, and 7.82 (95% CI 5.09-12.00) for non-GGnon-TT. Pooled synergy analysis revealed RERI = 4.08 (95% CI 3.15-5.27), AP = 0.50 (95% CI 0.42-0.57), S = 2.31 (95% CI 1.9-2.82), and V = 1.21 (95% CI 0.93-1.49).

CONCLUSION

This analysis revealed the synergistic and positive multiplicative effect of these two genes indicating that there is a common pathway of ARMS2/LOC387715 and CFH in AMD pathogenesis which may be the complement system pathway.

The presence of CFH, HTRA1, ARMS2, VEGF-A and VEGF-R and the appearance of age-related macular degeneration sub-types

OBJECTIVE

To demonstrate the genetic influence in the onset of the different age-related macular disease (AMD) subtypes by analysing the genotype distribution of CFH, ARMS2, HTRA1, VEGF-A and VEGF-R polymorphisms in patients with neovascular and atrophic AMD.

MATERIALS AND METHODS

The study was conducted on 101 consecutive patients with AMD diagnosis (74 exudative, 27 atrophic) following Wisconsin international classification criteria. The CFH rs1410996, ARMS2 rs10940923, VEGF-A rs833061, rs699947, and VEGF-R rs2071559 polymorphisms were analysed using real time PCR with taqman probes, and HTRA1 rs112000638 using restriction endonucleases digestion. A study was made of the genotype distribution of the different polymorphisms in our group of patients with neovascular AMD and those with the atrophic type, and a comparison was made of the results for each one of the genes studied.

RESULTS

No statistically significant differences (P>.05) were found in the genotype distribution of the different polymorphisms between patients with neovascular AMD and patients with atrophic AMD in our population, although the "risk" genotypes tended to appear more frequently in patients with neovascular AMD, despite the lack of statistical significance.

CONCLUSIONS

Allelic variants of CFH, ARMS2, HTRA1, VEGF-A or VEGF-R genes are not associated with the different AMD subtypes. This suggests that, although the polymorphisms seem to be associated with the disease susceptibility, they are not involved in the onset of the different clinical variants of AMD. Further studies in different populations, and with a larger cohort of patients, are needed to confirm these results.

The Application of Genetic Risk Scores in Age-Related Macular Degeneration: A Review

Age-related macular degeneration (AMD), a highly prevalent and impactful disease of aging, is inarguably influenced by complex interactions between genetic and environmental factors. Various risk scores have been tested that assess measurable genetic and environmental contributions to disease. We herein summarize and review the ability and utility of these numerous models for prediction of AMD and suggest additional risk factors to be incorporated into clinically useful predictive models of AMD.

Genome-wide association studies: getting to pathogenesis, the role of inflammation/complement in age-related macular degeneration

Age-related macular degeneration (AMD) is a chronic, degenerative, and significant cause of visual impairment and blindness in the elderly. Genetic and epidemiological studies have confirmed that AMD has a strong genetic component, which has encouraged the application of increasingly sophisticated genetic techniques to uncover the important underlying genetic variants. Although various genes and pathways have been implicated in the risk for AMD, complement activation has been emphasized repeatedly throughout the literature as having a major role both physiologically and genetically in susceptibility to and pathogenesis of this disease. This article explores the research efforts that brought about the discovery and characterization of the role of inflammatory and immune processes (specifically complement) in AMD. The focus herein is on the genetic evidence for the role of complement in AMD as supported specifically by genome-wide association (GWA) studies, which interrogate hundreds of thousands of variants across the genome in a hypothesis-free approach, and other genetic interrogation methods.

Gene ontology and KEGG enrichment analyses of genes related to age-related macular degeneration

Identifying disease genes is one of the most important topics in biomedicine and may facilitate studies on the mechanisms underlying disease. Age-related macular degeneration (AMD) is a serious eye disease; it typically affects older adults and results in a loss of vision due to retina damage. In this study, we attempt to develop an effective method for distinguishing AMD-related genes. Gene ontology and KEGG enrichment analyses of known AMD-related genes were performed, and a classification system was established. In detail, each gene was encoded into a vector by extracting enrichment scores of the gene set, including it and its direct neighbors in STRING, and gene ontology terms or KEGG pathways. Then certain feature-selection methods, including minimum redundancy maximum relevance and incremental feature selection, were adopted to extract key features for the classification system. As a result, 720 GO terms and 11 KEGG pathways were deemed the most important factors for predicting AMD-related genes.

The impact of the human genome project on complex disease

In the decade that has passed since the initial release of the Human Genome, numerous advancements in science and technology within and beyond genetics and genomics have been encouraged and enhanced by the availability of this vast and remarkable data resource. Progress in understanding three common, complex diseases: age-related macular degeneration (AMD), Alzheimer's disease (AD), and multiple sclerosis (MS), are three exemplars of the incredible impact on the elucidation of the genetic architecture of disease. The approaches used in these diseases have been successfully applied to numerous other complex diseases. For example, the heritability of AMD was confirmed upon the release of the first genome-wide association study (GWAS) along with confirmatory reports that supported the findings of that state-of-the art method, thus setting the foundation for future GWAS in other heritable diseases. Following this seminal discovery and applying it to other diseases including AD and MS, the genetic knowledge of AD expanded far beyond the well-known APOE locus and now includes more than 20 loci. MS genetics saw a similar increase beyond the HLA loci and now has more than 100 known risk loci. Ongoing and future efforts will seek to define the remaining heritability of these diseases; the next decade could very well hold the key to attaining this goal.

Age-related macular degeneration-clinical review and genetics update

Age-related macular degeneration (AMD) is the leading cause of central vision impairment in persons over the age of 50 years in developed countries. Both genetic and non-genetic (environmental) factors play major roles in AMD etiology, and multiple gene variants and lifestyle factors such as smoking have been associated with the disease. While dissecting the basic etiology of the disease remains a major challenge, current genetic knowledge has provided opportunities for improved risk assessment, molecular diagnosis and clinical testing of genetic variants in AMD treatment and management. This review addresses the potential of translating the wealth of genetic findings for improved risk prediction and therapeutic intervention in AMD patients. Finally, we discuss the recent advancement in genetics and genomics and the future prospective of personalized medicine in AMD patients.

Clinical applications of whole-genome association studies: future applications at the bedside

Until now, performing whole-genome association studies has been an unattainable, but highly desirable, goal for geneticists. With the recent advent of high-throughput genotyping platforms, this goal is now a reality for geneticists today and for clinicians in the not-so-distant future. This review will cover a broad range of topics to provide an overview of this emerging branch of genetics, and will provide references to more specific sources. Specifically, this review will cover the technologies available today and in the near future, the specific types of whole-genome association studies, the benefits and limitations of these studies, the applications to complex disease-gene interactions, diagnostic devices, therapeutics, and finally, we will describe the 5-year perspective and key issues.

Human complement factor H and factor H-like protein 1 are expressed in human retinal pigment epithelial cells

BACKGROUND

A common haplotype in the gene for the regulator of the alternative pathway of complement activation factor H has been linked to individual predisposition to age- related macular degeneration (AMD).

METHODS

In this study, retinal pigment epithelial (RPE) cells, i.e. immortalized ARPE-19 as well as primary human RPE cells, were investigated for expression of factor H and FHL-1 by immunohistochemistry and in situ hybridization analysis.

RESULTS

Factor H and the alternative spliced product FHL-1 are expressed in RPE cells, i.e. in immortalized ARPE-19 and primary human RPE cells. Factor H and FHL-1 expression was induced in a dose-dependent manner in ARPE-19 cells upon treatment with the inflammatory marker interleukin-6 (IL-6). In situ hybridization experiments confirmed an elevated expression rate of the factor H gene in IL-6-treated ARPE-19 cells. AMD is characterized by complement-associated inflammatory processes in the retina. Thus, local synthesis of complement regulators affects the protection of retinal cells and may be involved in the pathogenesis at the RPE-choroid interface.

Functional effect of Saffron supplementation and risk genotypes in early age-related macular degeneration: a preliminary report

Background

To determine whether the functional effects of oral supplementation with Saffron, a natural compound that proved to be neuroprotective in early age-related macular degeneration, are influenced by complement factor H (CFH) and age-related maculopathy susceptibility 2 (ARMS2) risk genotypes.

Methods

Thirty-three early AMD patients, screened for CFH (rs1061170) and ARMS2 (rs10490924) polymorphisms and receiving Saffron oral supplementation (20 mg/day) over an average period of treatment of 11 months (range, 6–12), were longitudinally evaluated by clinical examination and focal electroretinogram (fERG)-derived macular (18°) flicker sensitivity estimate. fERG amplitude and macular sensitivity, the reciprocal value of the estimated fERG amplitude threshold, were the main outcome measures.

Results

After three months of supplementation, mean fERG amplitude and fERG sensitivity improved significantly when compared to baseline values (p < 0.01). These changes were stable throughout the follow-up period. No significant differences in clinical and fERG improvements were observed across different CFH or ARMS2 genotypes.

Conclusions

The present results indicate that the functional effect of Saffron supplementation in individual AMD patients is not related to the major risk genotypes of disease.

Risk alleles in CFH and ARMS2 and the long-term natural history of age-related macular degeneration: the Beaver Dam Eye Study

OBJECTIVE

To describe the relationships of risk alleles in complement factor H (CFH, rs1061170) and age-related maculopathy susceptibility 2 (ARMS2, rs10490924) to the incidence and progression of age-related macular degeneration (AMD) during a 20-year period.

METHODS

There were 4282 persons aged 43 to 86 years at the baseline examination in 1988-1990 enrolled in a population-based cohort study who participated in at least 1 examination spaced 5 years apart during a 20-year period and had gradable fundus photographs for AMD and genotype information on CFH and ARMS2. Low, intermediate, and high genetic risk for AMD was defined by the presence of 0 to 1, 2, or 3 to 4 risk alleles for CFH and ARMS2, respectively. Multistate models were used to estimate the progression of AMD throughout the entire age range.

RESULTS

There were 2820 (66%), 1129 (26%), and 333 persons (8%) with low, intermediate, and high genetic risk for AMD, respectively. The 5-year incidences of early and late AMD were 9.1% and 1.6%, respectively, and increased with age but did not differ significantly by sex. Using the multistate model, of persons aged 45 years with no AMD in the low, intermediate, and high AMD genetic risk groups, 33.0%, 39.9%, and 46.5%, respectively, were estimated to develop early AMD, and 1.4%, 5.2%, and 15.3% were estimated to develop late AMD by age 80 years.

CONCLUSIONS

These population-based data provide estimates of the long-term risk of the incidence and progression of AMD and its lesions by age and genetic risk alleles for CFH and ARMS2. They also show that when early AMD is present, knowing the phenotype contributes more to risk assessment than knowing the genetic risk based on these 2 AMD genes.

Pharmacogenetics of antiangiogenic and antineovascular therapies of age-related macular degeneration

Age-related macular degeneration (AMD), the most common age-related disease causing irreversible visual loss in industrialized countries, is a complex and multifactorial illness. Researchers have found components of the complement alternative pathway inside drusen and Bruch's membrane of AMD patients, underlying a possible important role of complement factor H in the pathogenesis of AMD. The neovascular (wet) AMD is the most destructive form and it is characterized by invasion of new blood vessels into subretinal spaces with subsequent exudation and bleeding, resulting in scarring of the macular region and loss of the central vision. The hallmark of the neovascular form is the choroidal neovascularization, where VEGF-A has an important role in the pathogenesis of the disease. SNPs of these genes have recently been investigated as potential pharmacogenetic markers of the antiangiogenic and antineovascular therapy of AMD, which includes verteporfin photodynamic therapy and anti-VEGF-A drugs, such as pegaptanib, bevacizumab and ranibizumab. The CFH rs1061170 CT and TT genotypes have been associated with an improvement of visual acuity in bevacizumab or ranibizumab treated patients, whereas patients harboring VEGF-A rs699946 G allele responded better to bevacizumab-based therapy if compared with patients carrying the A allele. In conclusion, the discovery of pharmacogenetic markers for the personalization of the antiangiogenic and/or antineovascular therapy could be, in the future, a key issue in ophthalmology to obtain a personalization of the therapy and to avoid unnecessary costs and adverse drug reactions.

Genetic and functional dissection of ARMS2 in age-related macular degeneration and polypoidal choroidal vasculopathy

Age-related maculopathy susceptibility 2(ARMS2) was suggested to be associated with neovascular age-related macular degeneration (nAMD) and polypoidal choroidal vasculopathy (PCV) in multiple genetic studies in Caucasians and Japanese. To date, no biological properties have been attributed to the putative protein in nAMD and PCV. The complete genes of ARMS2 and HTRA1 including all exons and the promoter region were assessed using direct sequencing technology in 284 unrelated mainland northern Chinese individuals: 96 nAMD patients, 92 PCV patients and 96 controls. Significant associations with both nAMD and PCV were observed in 2 polymorphisms of ARMS2 and HTRA1 rs11200638, with different genotypic distributions between nAMD and PCV (p<0.001). After adjusting for rs11200638, ARMS2 rs10490924 remained significantly associated with nAMD and PCV (p<0.001). Then we overexpressed wild-type ARMS2 and ARMS2 A69S mutation (rs10490924) in RF/6A cells and RPE cells as in vitro study model. Cell proliferation, attachment, migration and tube formation were analyzed for the first time. Compare with wild-type ARMS2, A69S mutation resulted in a significant increase in proliferation and attachment but inhibited cell migration. Moreover, neither wild-type ARMS2 nor A69S mutation affected tube formation of RF/6A cells. There is a strong and consistent association of the ARMS2/HTRA1 locus with both nAMD and PCV, suggesting the two disorders share, at least partially, similar molecular mechanisms. Neither wild-type ARMS2 nor A69S mutation had direct association with neovascularisation in the pathogenesis of AMD.

Influence of CFH, HTRA1 and ARMS2 haplotype polymorphisms in the development of age-related macular disease

OBJECTIVE

To demonstrate genetic influence on the onset of age-related macular disease (AMD), analyzing genotype distribution of haplotypes, including polymorphisms of genes with proved relationships with AMD risk (CFH, ARMS2, HTRA1) in patients with AMD and in healthy people.

METHODS

We took 101 consecutive patients with an AMD diagnosis following Wisconsin international classification. For our control group, we took 91 patients without AMD or any significant macular changes. We analyzed CFH rs1410996, ARMS2rs 10940923 polymorphisms using real time PCR with taqman probes, and HTRA1 -625 using restriction endonuclease digestion. We studied haplotypes by simultaneously combining genotypes which, in previous studies, had been shown to have relationship with AMD (CFH, ARMS2, HTRA1) in patients with AMD and healthy people.

RESULTS

There was a statistically significant higher proportion of patients with AMD simultaneously expressing CFH GG (rs1410996) and ARMS2 TT (rs10940923) (P=.037; OR: 7.742 [1.010-63.156]); ARMS2 TT (rs10940923) and HTRA1-625 TT (P=.001; OR: 9.006 [2.019-40.168]) and CFH GG (rs1410996), ARMS2 TT (rs1040923) and HTRA1 -625 GG (P=.043; OR: 6.702 [1.003-55.565]) genotypes.

CONCLUSIONS

Haplotypes which combine "risk genotypes", demonstrated in previous studies, of our analyzed polymorphisms are more frequent in patients with AMD than in the control group, and they seem to increase the risk of suffering the disease in our population.

Genetic studies of age-related macular degeneration: lessons, challenges, and opportunities for disease management

BACKGROUND

Age-related macular degeneration (AMD) is a common cause of visual impairment in individuals >55 years of age worldwide. The varying clinical phenotypes of AMD result from contributions of genetic, epigenetic, and nongenetic (environmental) factors. Genetic studies of AMD have come of age as a direct result of tremendous gains from the human genome project, genome-wide association studies, and identification of numerous susceptibility loci. These findings have implicated immune response, high-density lipoprotein cholesterol metabolism, extracellular matrix, and angiogenesis signaling pathways in disease pathophysiology.

MAIN OUTCOME MEASURES

Herein, we address how the wealth of genetic findings in AMD is expected to impact the practice of medicine, providing opportunities for improved risk assessment, molecular diagnosis, preventive, and therapeutic intervention.

CONCLUSIONS

We propose that the potential of using genetic variants for monitoring treatment response (pharmacogenetics) may usher in a new era of personalized medicine in the clinical management of AMD.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosures may be found after the references.

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.