Age-related Macular Degeneration Genotype Research Articles

Роль курения, избыточной массы тела, генов СFH (rs1061170) и ARMS2 (rs10490924) у пациентов с сухой формой возрастной макулярной дегенерацией

Purpose. To evaluate the role of smoking, excess body weight, CFH and ARMS 2 gene polymorphisms in patients with the dry form of age-related macular degeneration (AMD). Material and мethods. There were selected seventy-five people (150 eyes) with overweight or obesity. They were checked for having a smoking habit. Their body mass index, and CFH and ARMS2 gene polymorphisms were determined. Patients underwent standard eye exam and retinal electrophysiological examination (EPI). Results. All patients were divided into two groups: overweight smokers and nonsmokers. The group of nonsmokers was significantly younger. Molecular genetic testing revealed more patients with low-risk AMD genotypes in the nonsmoking group and more patients with moderate-risk genotypes in the smoking group. Examination of the fundus showed that smokers in most cases have retinal changes typical for “AREDS category 2,3,4”; nonsmokers in most cases have “AREDS category 1” including normal retina. Thus, corrected visual acuity, static computer perimetry and EPI values were lower in the group of overweight smokers. Conclusion. The study results in the group of overweight patients who smoked were significantly lower because this group included patients with more severe stages of AMD with high-risk genotypes of the genes studied. Thus, smoking, overweight, SFH (rs1061170) and ARMS2 (rs10490924) polymorphisms may also be related to the risk of development and possibly progression of АMD. Keywords: age-related macular degeneration, smoking, overweight, СFH, ARMS2.

Adherence to the Mediterranean Diet and Progression to Late Age-Related Macular Degeneration in the Age-Related Eye Disease Studies 1 and 2

To determine whether closer adherence to a Mediterranean diet (and its individual components) was associated with altered risk of progression to late age-related macular degeneration (AMD) and large drusen. Additional objectives were to assess interactions with AMD genotype. Retrospective analysis of 2 controlled clinical trial cohorts: Age-Related Eye Disease Study (AREDS) and AREDS2. Eyes with no late AMD at baseline in AREDS participants (n= 4255) and AREDS2 participants (n= 3611): total of 13 204 eyes (7756 participants). Mean age was 71 years (standard deviation, 6.6); 56.5% were female. Color fundus photographs were collected at annual study visits and graded centrally for late AMD. The modified Alternative Mediterranean Diet Index (aMedi) score was calculated for each participant from food frequency questionnaires. Progression to late AMD, geographic atrophy (GA), and neovascular AMD; progression to large drusen. Over a median follow-up of 10.2 years, of the 13 204 eyes, 34.0% progressed to late AMD. Hazard ratios (HRs) for progression in aMedi tertile 3 versus 1 were 0.78 (95% confidence interval [CI], 0.71-0.85, P < 0.0001) for late AMD, 0.71 (0.63-0.80, P < 0.0001) for GA, and 0.84 (0.75-0.95, P= 0.005) for neovascular AMD. For fish consumption, HRs for late AMD in quartile 4 versus 1 were 0.69 (0.58-0.82, P < 0.0001; AREDS) and 0.92 (0.78-1.07, P= 0.28; AREDS2). In AREDS, both aMedi and its fish component interacted with CFH rs10922109 for late AMD (P= 0.01 and P= 0.0005, respectively); higher aMedi and fish intake were each associated with decreased risk only in participants with protective alleles. In separate analyses (n = 5029 eyes of 3026 AREDS participants), the HR for progression to large drusen in aMedi tertile 3 versus 1 was 0.79 (0.68-0.93, P= 0.004). Closer adherence to a Mediterranean-type diet was associated with lower risk of progression to late AMD and to large drusen. The signal was greater for GA than neovascular AMD. Fish intake contributed to this protective association. CFH genotype strongly influenced these relationships. These findings may help inform evidence-based dietary recommendations.

Clinically detectable drusen domains in fibulin-5-associated age-related macular degeneration (AMD) : Drusen subdomains in fibulin-5 AMD.

To evaluate whether drusen of subjects with fibulin-5 mutation-associated age-related macular degeneration (AMD) have clinically demonstrable drusen domains as evidenced by differences between color and fluorescein angiographic profiles. Of seven patients we identified with AMD due to mutations in the fibulin-5 gene (Fib-5 AMD), five had color fundus photography and fluorescein angiography (FA). One had bilateral choroidal neovascularization and no drusen. For each eye, the green channel (GC) of the digital RGB (Red-Green-Blue) color image and hyperfluorescent domain (HD) intensity of the FA image were registered and drusen were manually segmented and measured. Totally 75 small (≤62 μm), 110 intermediate (63-125 μm), and 30 large (>125 μm) drusen were measured in four patients within the 6×6mm central macular areas. All four subjects demonstrated central or paracentral HDs within each drusen perimeter. HDs were found in association with each druse, with a HD/GC ratio of 0.82, 0.76, and 0.72 respectively for small, intermediate, and large drusen (Student T Test: P<0.01, P<0.01, P<0.01). A statistical difference was found for the HD/GC ratios between small- and intermediate-sized drusen and small- and large-sized drusen but not between intermediate-sized and large-sized drusen (P=0.001, P<0.001, P>0.05, respectively). AMD patients with mutations in fibulin-5 share drusen phenotypic structure and have HD/GC ratios that are similar to individuals with cuticular or basal laminar drusen. Drusen substructure may reflect similarities in drusen stage and/or genesis and appear to vary among AMD genotypes.

Systems Biology Profiling of AMD on the Basis of Gene Expression.

Genetic pathways underlying the initiation and progression of age-related macular degeneration (AMD) have not been yet sufficiently revealed, and the correlations of AMD's genotypes, phenotypes, and disease spectrum are still awaiting resolution. We are tackling both problems with systems biology phylogenetic parsimony analysis. Gene expression data (GSE29801: NCBI, Geo) of macular and extramacular specimens of the retinas and retinal pigment epithelium (RPE) choroid complexes representing dry AMD without geographic atrophy (GA), choroidal neovascularization (CNV), GA, as well as pre-AMD and subclinical pre-AMD were polarized against their respective normal specimens and then processed through the parsimony program MIX to produce phylogenetic cladograms. Gene lists from cladograms' nodes were processed in Genomatix GePS to reveal the affected signaling pathway networks. Cladograms exposed a highly heterogeneous transcriptomic profiles within all the conventional phenotypes. Moreover, clades and nodal synapomorphies did not support the classical AMD phenotypes as valid transcriptomal genotypes. Gene lists defined by cladogram nodes showed that the AMD-related deregulations occurring in the neural retina were different from those in RPE-choroidal tissue. Our analysis suggests a more complex transcriptional profile of the phenotypes than expected. Evaluation of the disease in much earlier stages is needed to elucidate the initial events of AMD.

Genetic/Epigenetic Modulation, Ocular Diseases, and Therapeutic Prospective

Complex eye diseases often have significant genetic components. Previous work exploring the genetic contributions of ocular diseases has implicated numerous genomic regions and a variety of candidate genes as modulators of the disease susceptibility, including cataract, age-related macular degeneration (AMD), diabetic retinopathy (DR), glaucoma, high myopia, and others. With the advance of techniques both on genotyping and phenotyping, additional genes with a role in complex eye disease are waiting to be discovered. In contrast, it is apparent that a significant portion of the heritability of ocular disease cannot be explained through the alteration of DNA sequences. The field of epigenetics pursues the changes in gene expression or cellular phenotypes caused by mechanisms other than changes in the underlying DNA sequence. In general, epigenetic changes pertain to DNA methylation and histone modification. Aberrant epigenetic changes are associated with genomic instability and have been implicated in various human diseases. Recent advances in high-throughput platforms can generate voluminous data, which requires desperately the tools of system biology to effectively elucidate the true pictures underlying them. Knowledge and understanding of these genetic components and pathways have led to the development of promising therapies including small inference RNA (siRNA). This special issue contains 5 articles, the contents of which are summarized as follows. In the original paper “An extensive replication study on three new susceptibility loci of primary angle closure glaucoma in Han Chinese: Jiangsu Eye Study” by A. Shi et al., the authors tried to replicate recent findings of three new susceptibility loci for primary angle closure glaucoma (PACG) reported by a genome-wide association study. For a long time, the genetic study on glaucoma has been focused on primary angle open glaucoma. Instead of using clinical diagnosis of PACG as the phenotype to study, the authors chose a preclinical condition, primary angle closure (PAC), and same anatomical features of eyes to investigate. This community-based study did not find any significant association between the defined phenotypes and the single nucleotide polymorphisms in PLEKHA7, COL11A1, and PCMTD1-ST18. In the review paper “Vascular adhesion protein 1 in the eye” by W. Luo et al., the authors gave an overview on the new research progresses of VAP-1 in the ocular diseases including uveitis, AMD, DR, and ocular tumor. Based on the properties and results obtained so far from preclinical and clinical studies VAP-1 may provide a novel research direction or a potent therapeutic strategy for ophthalmological diseases. In the original paper “RNA interference targeting connective tissue growth factor inhibits the transforming growth factor-β2 induced proliferation in human Tenon capsule fibroblasts” by J. Jing et al., the authors showed that siRNA could efficiently prevent TGF-β2 induced proliferation of human Tenon capsule fibroblast, through targeting CTGF gene expression. Therefore, a siRNA based therapeutic approach was proposed for eliminating filtration bleb scarring after glaucoma filtration surgery. In the original paper “RNA interference targeting snail inhibits the transforming growth factor β2-induced epithelial-mesenchymal transition in human lens epithelial cells” by P. Li et al., the authors tested the concept to use Snail targeting siRNA to block TGF β2-induced proliferation in human lens epithelial cells. The results show that epithelial-mesenchymal transition was inhibited by Snail targeting siRNA in the model system that the article described, accompanied by the suppression on snail expression. The finding is informative for the design of the preventive strategy on posterior capsule opacification after cataract surgery. In the original paper “Systems biology profiling of AMD on the basis of gene expression” by M. S. Abu-Asab et al., a systems biology analytical paradigm called parsimony phylogenetics was used to reveal the various transcriptomic profiles of AMD's subtypes. Genetic pathways underlying the initiation and progression of AMD and the correlations of AMD's genotypes, phenotypes, and disease spectrum were investigated. On the whole, the papers contained in this special issue covered the most active fields of genetic studies on complex eye diseases. Jingsheng Tuo Lai Wei Nan Hu

Relationship Among CFH and ARMS2 Genotypes, Macular Pigment Optical Density, and Neuroretinal Function in Persons Without Age-Related Macular Degeneration

OBJECTIVES To determine whether there is a difference in neuroretinal function and in macular pigment optical density between persons with high- and low-risk gene variants for age-related macular degeneration (AMD) and no ophthalmoscopic signs of AMD, and to compare the results on neuroretinal function to patients with manifest early AMD. METHODS Neuroretinal function was assessed with the multifocal electroretinogram for 32 participants (22 healthy persons with no AMD and 10 patients with early AMD). The 22 healthy participants with no AMD had either high- or low-risk genotypes for CFH (rs380390) and/or ARMS2 (rs10490924). Trough-to-peak response densities and peak-implicit times were analyzed in 5 concentric rings. Macular pigment optical density was assessed by use of customized heterochromatic flicker photometry. RESULTS Trough-to-peak response densities for concentric rings 1 to 3 were, on average, significantly greater in participants with high-risk genotypes than in participants with low-risk genotypes and in persons with early AMD after correction for age and smoking (P&lt;.05). The group peak-implicit times for ring 1 were, on average, delayed in the patients with early AMD compared with the participants with high- or low-risk genotypes, although these differences were not significant. There was no significant correlation between genotypes and macular pigment optical density. CONCLUSIONS Increased neuroretinal activity in persons who carry high-risk AMD genotypes may be due to genetically determined subclinical inflammatory and/or histological changes in the retina. Neuroretinal function in healthy persons genetically susceptible to AMD may be a useful additional early biomarker (in combination with genetics) of AMD before there is a clinical manifestation.

Inhibiting Alternative Pathway Complement Activation by Targeting the Factor D Exosite

By virtue of its amplifying property, the alternative complement pathway has been implicated in a number of inflammatory diseases and constitutes an attractive therapeutic target. An anti-factor D Fab fragment (AFD) was generated to inhibit the alternative complement pathway in advanced dry age-related macular degeneration. AFD potently prevented factor D (FD)-mediated proteolytic activation of its macromolecular substrate C3bB, but not proteolysis of a small synthetic substrate, indicating that AFD did not block access of the substrate to the catalytic site. The crystal structures of AFD in complex with human and cynomolgus FD (at 2.4 and 2.3 Å, respectively) revealed the molecular details of the inhibitory mechanism. The structures show that the AFD-binding site includes surface loops of FD that form part of the FD exosite. Thus, AFD inhibits FD proteolytic function by interfering with macromolecular substrate access rather than by inhibiting FD catalysis, providing the molecular basis of AFD-mediated inhibition of a rate-limiting step in the alternative complement pathway.

Genotypic Influences on Severity of Exudative Age-Related Macular Degeneration

Major genetic risk factors have recently been identified for age-related macular degeneration (AMD), including the ARMS2/LOC387715 and CFH at-risk polymorphisms. The study was conducted to establish correlations between the AMD genotype and both the phenotype and severity of AMD. In a prospective cohort of 1216 AMD patients, four genotypic homozygous groups were identified (n = 264): double homozygous for wild-type alleles (group 1, n = 49), homozygous for the at-risk allele of ARMS2/LOC387715 only (group 2, n = 57), homozygous for the at-risk allele of CFH only (group 3, n = 106), and double homozygous for both at-risk alleles (group 4, n = 52). The phenotypic classification of exudative AMD was based on fluorescein angiography. Mean age at presentation was significantly lower in group 4 than in group 1 (P < 0.014). Patients in group 4 presented more often with bilateral CNV and fibrovascular scars than did patients in group 1 (P < 0.001 and < 0.0031 respectively) and with significantly lower visual acuity (VA) in the first affected eye than did patients in group 1 (P < 0.02). Patients in group 2 presented with worse VA than did patients in group 3 (P < 0.003). Classic CNV was more commonly associated with the at-risk allele of the ARMS2/LOC387715 locus than with the at-risk allele of the CFH gene (P < 0.026). This study demonstrates an association between the at-risk allele of the ARMS2/LOC387715 locus and classic CNV, fibrovascular lesions, and poor VA. Individuals double homozygous for both at-risk alleles had a higher risk of being affected with a severe form of AMD at an earlier age.

Small, Hard Macular Drusen and Peripheral Drusen: Associations with AMD Genotypes in the Inter99 Eye Study

To study associations of small, hard macular drusen and peripheral drusen with genotypes associated with age-related macular degeneration (AMD). Digital grayscale fundus photographs recorded in red-free illumination were graded for the presence of drusen in 1107 subjects aged 30 to 66 years. Participants were genotyped for AMD-related polymorphisms in complement factor H (CFH), in LOC387715, and in complement factor B (CFB). The prevalence of 20 or more small, hard macular drusen per eye was 14%, with no association to the investigated polymorphisms. Peripheral drusen were associated with CFHY402H (odds ratio [OR], 4.3; 95% confidence interval [95% CI], 1.4-13, for CC versus TT genotypes) as was macular drusen >63 microm (OR, 1.9; 95% CI, 1.1-3.1, for CC versus TT genotypes). Macular drusen >63 microm were associated with the presence of 20 or more small, hard macular drusen (OR, 1.7; 95% CI, 1.1-2.6) and with peripheral drusen (OR, 2.5; 95% CI,1.2-5.4) In this study, the presence of 20 or more small, hard macular drusen per eye was not associated with known AMD-related polymorphisms, whereas the study confirmed an association of peripheral drusen with CFHY402H. (ClinicalTrials.gov number, NCT00289237).

Plasma Complement Components and Activation Fragments: Associations with Age-Related Macular Degeneration Genotypes and Phenotypes

Several genes encoding complement system components and fragments are associated with age-related macular degeneration (AMD). This study was conducted to determine whether alterations in circulating levels of these markers of complement activation and regulation are also independently associated with advanced AMD and whether they are related to AMD genotypes. Plasma and DNA samples were selected from individuals in our AMD registry who had progressed to or developed the advanced stages of AMD, including 58 with geographic atrophy and 62 with neovascular disease. Subjects of similar age and sex, but without AMD, and who did not progress were included as controls (n = 60). Plasma complement components (C3, CFB, CFI, CFH, and factor D) and activation fragments (Bb, C3a, C5a, iC3b, and SC5b-9) were analyzed. DNA samples were genotyped for seven single-nucleotide polymorphisms in six genes previously shown to be associated with AMD: CFB, CFH, C2, C3, and CFI and the LOC387715/ARMS2 gene region. The association between AMD and each complement biomarker was assessed by using logistic regression, controlling for age, sex, and proinflammatory risk factors: smoking and body mass index (BMI). Functional genomic analyses were performed to assess the relationship between the complement markers and genotypes. Concordance, or C, statistics were calculated to assess the effect of complement components and activation fragments in an AMD gene-environment prediction model. The highest quartiles of Bb and C5a were significantly associated with advanced AMD, when compared with the lowest quartiles. In multivariate models without genetic variants, the odds ratio (OR) for Bb was 3.3 (95% confidence interval [CI] = 1.3-8.6), and the OR for C5a was 3.6 (95% CI = 1.2-10.3). With adjustment for genetic variants, these ORs were substantially higher. The alternative pathway regulator CFH was inversely associated with AMD in the model without genotypes (OR = 0.3; P = 0.01). Positive associations were found between BMI and plasma C3, CFB, CFH, iC3b, and C3a. There were also significant associations between C5a fragment and LOC387715/ARMS2 and C3 genotypes (P for trend = 0.02, 0.04), respectively. C statistics for models with behavioral and genetic factors increased to 0.94 +/- 0.20 with the addition of C3a, Bb, and C5a. Increased levels of activation fragments Bb and C5a are independently associated with AMD. Higher BMI is related to increased levels of complement components. C5a is associated with AMD genotypes. C statistics are stronger with the addition of C3a, Bb, and C5a in predictive models. Results implicate ongoing activation of the alternative complement pathway in AMD pathogenesis.

Plasma Complement Components and Activation Fragments: Associations with Age-Related Macular Degeneration Genotypes and Phenotypes

Plasma Complement Components and Activation Fragments: Associations with Age-Related Macular Degeneration Genotypes and Phenotypes

An integrated hypothesis that considers drusen as biomarkers of immune-mediated processes at the RPE-Bruch's membrane interface in aging and age-related macular degeneration.

Age-related macular degeneration (AMD) is a blinding disease that afflicts millions of adults in the Western world. Although it has been proposed that a threshold event occurs during normal aging which leads to AMD, the sequelae of biochemical, cellular, and/or molecular events leading to the development of AMD are poorly understood. Although available data provide strong evidence that a significant proportion of AMD has a genetic basis, no gene(s) has yet been identified that causes a significant proportion of AMD. Moreover, no major molecular pathways involved in the etiology of this disease have been elucidated.Drusen, pathological deposits that form between the retinal pigmented epithelium (RPE) and Bruch's membrane, are significant risk factors for the development of AMD. In our view, the development of testable new hypotheses of drusen origins has been hindered significantly by the absence of a comprehensive profile of their molecular composition. In this review, we describe an integrated ultrastructural, histochemical, molecular biological, and biochemical approach to identify specific molecular pathways associated with drusen biogenesis. The implicit assumption underlying these recent investigations has been that a thorough understanding of the composition of drusen and source(s) of drusen-associated material is likely to provide fresh insight into the pathobiology underlying AMD. Significantly, these studies have revealed that proteins associated with inflammation and immune-mediated processes are prevalent among drusen-associated constituents. Transcripts that encode a number of these molecules have been detected in retinal, RPE, and choroidal cells. These data have also lead to the observations that dendritic cells, potent antigen-presenting cells, are intimately associated with drusen development and that complement activation is a key pathway that is active both within drusen and along the RPE-choroid interface. We propose herein a unifying hypothesis of drusen biogenesis that attempts to incorporate a large body of new and previously published structural, histochemical, and molecular data pertaining to drusen composition and development. This theory is put forth with the acknowledgment that numerous AMD genotypes may exist. Thus, only some aspects of the proposed hypothesis may be involved in any given AMD genotype. Importantly, this hypothesis invokes, for the first time, the potential for a direct role of cell- and immune-mediated processes in drusen biogenesis. We acknowledge that the proposed hypothesis clearly represents a paradigm shift in our conceptualization pertaining to pathways that participate in the development of drusen and age-related macular degeneration. It is our hope that other investigators will test, validate and/or refute various aspects of this hypothesis, and in so doing, increase our overall understanding of the biological pathways associated with early AMD.