Polymorphism p.402Y>H in the complement factor H protein is a risk factor for age related macular degeneration in an Italian population

Complement Inhibitors in Age-Related Macular Degeneration: A Potential Therapeutic Option

Age-related macular degeneration (AMD) is a multifactorial disease, which can culminate in irreversible vision loss and blindness in elderly. Nowadays, there is a big gap between dry AMD and wet AMD on treatment. Accounting for nearly 90% of AMD, dry AMD still lacks effective treatment. Numerous genetic and molecular researches have confirmed the significant role of the complement system in the pathogenesis of AMD, leading to a deeper exploration of complement inhibitors in the treatment of AMD. To date, at least 14 different complement inhibitors have been or are being explored in AMD in almost 40 clinical trials. While most complement inhibitors fail to treat AMD successfully, two of them are effective in inhibiting the rate of GA progression in phase II clinical trials, and both of them successfully entered phase III trials. Furthermore, recently emerging complement gene therapy and combination therapy also offer new opportunities to treat AMD in the future. In this review, we aim to introduce genetic and molecular associations between the complement system and AMD, provide the updated progress in complement inhibitors in AMD on clinical trials, and discuss the challenges and prospects of complement therapeutic strategies in AMD.

Analysis of complement deposition and viral RNA in placentas of COVID-19 patients

COVID-19, the disease caused by the novel Coronavirus, SARS-CoV-2, is increasingly being recognized as a systemic thrombotic and microvascular injury syndrome that may have its roots in complement activation. We had the opportunity to study the placental pathology of five full-term births to COVID-19 patients. All five exhibited histology indicative of fetal vascular malperfusion characterized by focal avascular villi and thrombi in larger fetal vessels. Vascular complement deposition in the placentas was not abnormal, and staining for viral RNA and viral spike protein was negative. While all cases resulted in healthy, term deliveries, these findings indicate the systemic nature of COVID-19 infection. The finding of vascular thrombosis without complement deposition may reflect the systemic nature of COVID-19's procoagulant effects unrelated to systemic complement activation.

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This paper explores thrombosis in the placentas COVID-19-positive patients at our hospital

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Potential prothrombotic mechanisms are explored.

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Direct infection of the placentas is ruled out as a cause.

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.

CFH Y402H polymorphism in Italian patients with age-related macular degeneration, retinitis pigmentosa, and Stargardt disease

BACKGROUND

The complement system has been implicated in the pathogenesis of age-related macular degeneration (AMD) and the CFH Y402H polymorphism has been suggested as a major risk factor for AMD. Recent evidences supported the role of inflammation in the pathogenesis of some retinal dystrophies. Aim of this study was to evaluate the prevalence of CFHY402H polymorphism in a group of Italian patients affected by atrophic AMD, Stargardt disease (STGD), or retinitis pigmentosa(RP).

MATERIALS AND METHODS

Our case-control association study included 116 patients with atrophic AMD, 77 with RP, 86 with STGD, and 100 healthy controls. All the patients were evaluated by a standard ophthalmologic examination and OCT. ERG was performed on STGD and RP patients. All the subjects underwent a blood drawing for genetic testing and the CFHY402H polymorphism was genotyped with the TaqMan real-time polymerase chain reaction single nucleotide polymorphism assay.

RESULTS

The prevalence of the risk genotype C/C was higher in the AMD group than in controls (p < 0.001). The risk allele C was more frequent in the AMD group than in controls (p < 0.001). The prevalence of the risk genotype was higher in the RP patients than in controls (p < 0.001) and similarly the risk allele C was more frequent in the RP group (p = 0.008). The CFHY402H genotype distribution was not different between patients with STGD and the controls, for the biallelic (p = 0.531) and for the monoallelic (p = 0.318) evaluation.

CONCLUSIONS

In our series of Italian patients, the CFHY402H genotype is associated with atrophic AMD and RP, but not with STGD. This result may support the hypothesis of a complement system dysregulation in the pathogenesis of AMD and RP.

C-reactive protein and complement factor H polymorphism interaction in advanced exudative age-related macular degeneration

PURPOSE

To determine the association of C-reactive protein (CRP) and complement factor H (CFH) gene with exudative age-related macular degeneration (AMD) and any possible interaction among these factors.

METHODS

In this case-control study, 139 unrelated patients with exudative AMD and 123 non-AMD controls were recruited. Blood sample was taken for analysis of the CRP levels and DNA testing. DNA fragments of CFH gene variants containing 4 single nucleotide polymorphisms including rs800292, rs1061170, rs2274700, and rs3753395 were assessed. A CRP level of ≥3 mg/L was considered as elevated. The association of elevated CRP and CFH gene variants polymorphism with exudative AMD was compared between the groups.

RESULTS

Mean age was 72.6 ± 6.4 for controls and 74.9 ± 7.4 for case group (P = 0.006). The difference between CRP levels in cases and controls was not statistically significant (P = 0.055). However, Y402H variant of CFH in both homozygous and heterozygous carriers C allele was significantly more frequent among exudative AMD patients than controls, 32.1 versus 6.5 % (P < 0.001). Evaluating various CRP levels in patients with CC and non-CC genotypes disclosed that in CC genotype group, higher CRP level (>3 mg/L) was associated with higher risk of developing exudative AMD (OR = 12.0, CI: 1.5-98.8) compared with the control group.

CONCLUSION

This study disclosed no difference in CRP levels per se between exudative AMD patients with control group. However, higher levels of CRP in the presence of C allele of Y402H might confer more risk for the development of exudative AMD.

Aptamers in Therapeutics

Aptamers are single strand DNA or RNA molecules, selected by an iterative process known as Systematic Evolution of Ligands by Exponential Enrichment (SELEX). Due to various advantages of aptamers such as high temperature stability, animal free, cost effective production and its high affinity and selectivity for its target make them attractive alternatives to monoclonal antibody for use in diagnostic and therapeutic purposes. Aptamer has been generated against vesicular endothelial growth factor 165 involved in age related macular degeneracy. Macugen was the first FDA approved aptamer based drug that was commercialized. Later other aptamers were also developed against blood clotting proteins, cancer proteins, antibody E, agents involved in diabetes nephropathy, autoantibodies involved in autoimmune disorders, etc. Aptamers have also been developed against viruses and could work with other antiviral agents in treating infections.

Investigating the CFH Gene Polymorphisms as a Risk Factor for Age-related Macular Degeneration in an Iranian Population

BACKGROUND

Age-related macular degeneration (AMD) is a complex disorder which results in irreversible vision loss and progressive impairment of central vision. Disease susceptibility is influenced by multiple genetic and environmental factors. Single nucleotide polymorphisms (SNP) in the complement factor H gene are the most important genetic risk factors. We conducted a case-control study to investigate the association four SNPs (dbSNP ID: rs800292, rs1061170, rs2274700 and rs3753395) of CFH gene with AMD in the Iranian population.

MATERIALS AND METHODS

We recruited 100 AMD patients and 100 age- and sex-matched normal controls. Direct sequencing for three SNPs (rs800292, rs2274700 and rs3753395) and restriction fragment length polymorphism utilized for rs1061170. Allele and genotype frequencies of SNPs were calculated and tested for departure from Hardy-Weinberg equilibrium using the Chi-square test. An allelic and genotypic association was compared by logistic regression analysis using the SNPassoc.

RESULTS

According to our results, the frequencies of risk allele for all SNPs (G, G, A, and C alleles of rs800292, rs2274700, rs3753395 and rs1061170, respectively) were significantly higher in AMD patients (p value < 0.001). AMD individuals who had at least one copy of the C allele of rs1061170 had an increased risk of disease compared with cases with the T allele. Other studied polymorphisms showed the same association.

CONCLUSION

Our results suggest the contribution of all four predicted CFH polymorphisms in AMD susceptibility among the Iranian population. This association with CFH may lead to early detection and new strategies for prevention and treatment of AMD.

Human retinal transmitochondrial cybrids with J or H mtDNA haplogroups respond differently to ultraviolet radiation: implications for retinal diseases

Background

It has been recognized that cells do not respond equally to ultraviolet (UV) radiation but it is not clear whether this is due to genetic, biochemical or structural differences of the cells. We have a novel cybrid (cytoplasmic hybrids) model that allows us to analyze the contribution of mitochondrial DNA (mtDNA) to cellular response after exposure to sub-lethal dose of UV. mtDNA can be classified into haplogroups as defined by accumulations of specific single nucleotide polymorphisms (SNPs). Recent studies have shown that J haplogroup is high risk for age-related macular degeneration while the H haplogroup is protective. This study investigates gene expression responses in J cybrids versus H cybrids after exposure to sub-lethal doses of UV-radiation.

Methodology/Principal Findings

Cybrids were created by fusing platelets isolated from subjects with either H (n = 3) or J (n = 3) haplogroups with mitochondria-free (Rho⁰) ARPE-19 cells. The H and J cybrids were cultured for 24 hours, treated with 10 mJ of UV-radiation and cultured for an additional 120 hours. Untreated and treated cybrids were analyzed for growth rates and gene expression profiles. The UV-treated and untreated J cybrids had higher growth rates compared to H cybrids. Before treatment, J cybrids showed lower expression levels for CFH, CD55, IL-33, TGF-A, EFEMP-1, RARA, BCL2L13 and BBC3. At 120 hours after UV-treatment, the J cybrids had decreased CFH, RARA and BBC3 levels but increased CD55, IL-33 and EFEMP-1 compared to UV-treated H cybrids.

Conclusion/Significance

In cells with identical nuclei, the cellular response to sub-lethal UV-radiation is mediated in part by the mtDNA haplogroup. This supports the hypothesis that differences in growth rates and expression levels of complement, inflammation and apoptosis genes may result from population-specific, hereditary SNP variations in mtDNA. Therefore, when analyzing UV-induced damage in tissues, the mtDNA haplogroup background may be important to consider.

Age-Related Macular Degeneration: Pathogenesis, Genetic Background, and the Role of Nutritional Supplements

Age-related macular degeneration (ARMD) is the leading cause of severe vision loss and blindness worldwide, mainly affecting people over 65 years old. Dry and wet ARDM are the main types of the disease, which seem to have a multifactorial background. The aim of this review is to summarize the mechanisms of ARMD pathogenesis and exhibit the role of diet and nutritional supplements in the onset and progression of the disease. Environmental factors, such as smoking, alcohol, and, diet appear to interact with mutations in nuclear and mitochondrial DNA, contributing to the pathogenesis of ARMD. Inflammatory mediators and oxidative stress, induced by the daily exposure of retina to high pressure of oxygen and light radiation, have been also associated with ARMD lesions. Other than medical and surgical therapies, nutritional supplements hold a significant role in the prevention and treatment of ARMD, eliminating the progression of macular degeneration.

Impairment of the ubiquitin-proteasome pathway in RPE alters the expression of inflammation related genes

The ubiquitin-proteasome pathway (UPP) plays an important role in regulating gene expression. Retinal pigment epithelial cells (RPE) are a major source of ocular inflammatory cytokines. In this work we determined the relationship between impairment of the UPP and expression of inflammation-related factors. The UPP could be impaired by oxidative stress or chemical inhibition. Impairment of the UPP in RPE increased the expression of several inflammatory cytokines, such as IL-6 and IL-8. However, the expression of monocyte chemoattractant protein-1 (MCP-1) and complement factor H (CFH) and was reduced upon impairment of the UPP. These data suggest that impairment of the UPP in RPE may be one of the causes of retinal inflammation and abnormal functions of monocyte and the complement system during the pathogenesis of age-related macular degeneration.

Association of single nucleotide polymorphisms in CFH, ARMS2 and HTRA1 genes with risk of age-related macular degeneration in Egyptian patients

BACKGROUND

Age-related macular degeneration (AMD) is one of the leading causes of blindness in the elderly worldwide. Several single nucleotide polymorphisms (SNPs) have been linked to the risk of developing AMD. We aimed to examine the association between AMD and SNPs on CFH, ARMS2 and HTRA1 in Egyptians, a previously unstudied population.

MATERIALS AND METHODS

Genomic DNA was extracted from 26 AMD patients and 20 controls. Genotyping was performed using PCR followed by allele-specific restriction digestion and direct sequencing.

RESULTS

CFH rs1061170 was significantly associated with AMD with the frequency of the risk C allele being 0.53 in patients and 0.17 in controls (p < 0.017). The odds ratio (OR) for the TC genotype was 5.5 (95% CI: 1.1-26.4) and for combined TC + CC genotypes was 8 (95% CI: 1.7-37.1). ARMS2 rs10490924 was also significantly associated with the risk allele T found at a frequency of 0.5 in AMD and 0.15 in controls (p < 0.017, χ(2) test). The OR for the TG genotype was 4.667 (95% CI: 1.2-18.4) and for combined TG + TT genotypes was 7 (95% CI: 1.8-26.5). HTRA1 rs11200638 also was significantly associated, with the risk allele A found at a frequency of 0.44 in patients and 0.17 in controls (p < 0.017, χ(2) test). OR for GA genotype was 5 (95% CI: 1.2-20.9) and for the combined GA + AA genotypes was 6 (95% CI: 1.4-24.7).

CONCLUSIONS

Our data demonstrates significant association between AMD and rs1061170 on CFH, rs10490924 on ARMS2 and rs11200638 on HTRA1 in Egyptian patients. These findings are in agreement with previous findings in Caucasians.

Association between CFH Y402H polymorphism and age related macular degeneration in North Indian cohort

The purpose of the study was to determine serum complement factor H (CFH) levels in patients of age related macular degeneration (AMD) and examine its association with CFH Y402H polymorphism. 115 AMD patients and 61 normal controls were recruited in this study. The single nucleotide polymorphism was assayed by real time PCR and serum CFH levels were measured by ELISA and standardized to total serum protein. Chi-square test was applied to polymorphism analysis while Mann Whitney U-statistic for CFH-levels. Mendelian randomization approach was used for determining causal relationship. The genotype frequency differed between the AMD patients (TT- 18.3%, TC-41.3% and CC-40.4%) and controls (TT-76.3%, TC-13.6%, and CC-10.1%) (p = 0001). The frequency of alleles was also significantly different when AMD (T-39% and C-61%) was compared to controls (T-83% and C-17%) (p = 0.0001). Level of serum CFH was significantly lower in AMD patients as compared to normal controls (p = 0.001). Our data showed that the CFH Y402H polymorphism is a risk factor for AMD in the North Indian population. Mendelian randomization approach revealed that CFH Y402H polymorphism affects AMD risk through the modification of CFH serum levels.

Y402H polymorphism in complement factor H and age-related macular degeneration in the Tunisian population

To evaluate a possible association between the complement factor H (CFH) Y402H polymorphism and susceptibility to age-related macular degeneration (AMD) in the Tunisian population, as well as the impact of the genotype distribution among different phenotypes and the response to treatment with intravitreal bevacizumab, exon 9 of CFH was analyzed for the Y402H polymorphism by direct sequencing in 135 healthy controls and 127 sporadic unrelated AMD patients classified into the following groups: 12 atrophic AMD (group G1), 115 exudative AMD (G2) and 10 AMD patients who had fibrovascular scarring (G3) that did not allow a precise grading of the phenotype. Seventy patients in G2 were treated with 1.25 mg intravitreal bevacizumab at 6-week intervals until choroidal neovascularization (CNV) was no longer active. The frequency of the CFH 402H allele was significantly higher in AMD patients than in controls (p = 2.62 × 10(-16)). However, subgroup analysis does not reveal any association between the variant allele H and phenotypes of AMD or CNV. Also, there was no significant difference in response to bevacizumab treatment according to Y402H CFH genotype (p = 0.59). A strong association of the 402H allele with susceptibility to AMD in the Tunisian population was confirmed; however, this variant does not appear to be involved in the clinical progression of this disease or in the postintravitreal bevacizumab response.

Single nucleotide polymorphisms in MCP-1 and its receptor are associated with the risk of age related macular degeneration

Background

Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly population. We have shown previously that mice deficient in monocyte chemoattractant protein-1 (MCP1/CCL2) or its receptor (CCR2) develop the features of AMD in senescent mice, however, the human genetic evidence so far is contradictory. We hypothesized that any dysfunction in the CCL2 and its receptor result could be the contributing factor in pathogenesis of AMD.

Methods and Findings

133 AMD patients and 80 healthy controls were enrolled for this study. Single neucleotid Polymorphism for CCL2 and CCR2 was analyzed by real time PCR. CCL2 levels were determined by enzyme-linked immunosorbent assay (ELISA) after normalization to total serum protein and percentage (%) of CCR2 expressing peripheral blood mononuclear cells (PBMCs) was evaluated using Flow Cytometry. The genotype and allele frequency for both CCL2 and CCR2 was found to be significantly different between AMD and normal controls. The CCL2 ELISA levels were significantly higher in AMD patients and flow Cytometry analysis revealed significantly reduced CCR2 expressing PBMCs in AMD patients as compared to normal controls.

Conclusions

We analyzed the association between single neucleotide polymorphisms (SNPs) of CCL2 (rs4586) and CCR2 (rs1799865) with their respective protein levels. Our results revealed that individuals possessing both SNPs are at a higher risk of development of AMD.

Lutein and zeaxanthin supplementation reduces photooxidative damage and modulates the expression of inflammation-related genes in retinal pigment epithelial cells

Oxidative damage and inflammation are related to the pathogenesis of age-related macular degeneration (AMD). Epidemiologic studies suggest that insufficient dietary lutein and zeaxanthin intake or lower serum zeaxanthin levels are associated with increased risk for AMD. The objective of this work is to test the protective effects of lutein and zeaxanthin against photooxidative damage to retinal pigment epithelial cells (RPE) and oxidation-induced changes in expression of inflammation-related genes. To mimic lipofuscin-mediated photooxidation in vivo, we used ARPE-19 cells that accumulated A2E, a lipofuscin fluorophore and photosensitizer, as a model system to investigate the effects of lutein and zeaxanthin supplementation. The data show that supplementation with lutein or zeaxanthin in the medium resulted in accumulation of lutein or zeaxanthin in the RPE cells. The concentrations of lutein and zeaxanthin in the cells were 2- to 14-fold of that detected in the medium, indicating that ARPE-19 cells actively take up lutein or zeaxanthin. As compared with untreated cells, exposure of A2E-containing RPE to blue light resulted in a 40-60% decrease in proteasome activity, a 50-80% decrease in expression of CFH and MCP-1, and an~20-fold increase in expression of IL-8. The photooxidation-induced changes in expression of MCP-1, IL-8, and CFH were similar to those caused by chemical inhibition of the proteasome, suggesting that inactivation of the proteasome is involved in the photooxidation-induced alteration in expression of these inflammation-related genes. Incubation of the A2E-containing RPE with lutein or zeaxanthin prior to blue light exposure significantly attenuated the photooxidation-induced inactivation of the proteasome and photooxidation-induced changes in expression of MCP-1, IL-8, and CFH. Together, these data indicate that lutein or zeaxanthin modulates inflammatory responses in cultured RPE in response to photooxidation. Protecting the proteasome from oxidative inactivation appears to be one of the mechanisms by which lutein and zeaxanthin modulate the inflammatory response. Similar mechanisms may explain salutary effects of lutein and zeaxanthin in reducing the risk for AMD.

Plasma levels of complement proteins from the alternative pathway in patients with age-related macular degeneration are independent of Complement Factor H Tyr⁴⁰²His polymorphism

PURPOSE

To investigate the influence of the Factor H (CFH) Tyr⁴⁰²His polymorphism on the plasma levels of the alternative pathway proteins CFH, C3, Factor B (FB), Factor D (FD), and Factor I (FI) and the inflammatory marker C-reactive protein (CRP) in 119 patients with age-related macular degeneration (AMD) and 152 unrelated control individuals.

METHODS

Patients with AMD and the control group were separated according to CFH polymorphism, age, and gender. Plasma complement proteins and CRP concentrations were determined with enzyme-linked immunosorbent assay, immunodiffusion, or nephelometry.

RESULTS

Significant differences in the concentrations of FD and FI were observed between the patients with AMD and the control individuals. We observed significantly reduced FD plasma levels in patients with AMD. We also identified a significant decrease in CFH plasma levels in female patients with AMD in relation to female controls. Plasma FI levels were significantly increased in patients with AMD compared to the control group. Regarding gender, a significant increase in FI plasma levels was observed in male patients. Finally, we found no significant correlation between the CFH Tyr(402)His polymorphism and the CFH, C3, FB, FD, FI, and CRP plasma levels.

CONCLUSIONS

Patients with AMD present altered levels of FD and FI in a manner independent of this CFH polymorphism, and gender apparently contributes to the plasma levels of these two proteins in patients with AMD and control individuals.

Complement factor H genetic variant and age-related macular degeneration: effect size, modifiers and relationship to disease subtype

BACKGROUND

Variation in the complement factor H gene (CFH) is associated with risk of late age-related macular degeneration (AMD). Previous studies have been case-control studies in populations of European ancestry with little differentiation in AMD subtype, and insufficient power to confirm or refute effect modification by smoking.

METHODS

To precisely quantify the association of the single nucleotide polymorphism (SNP rs1061170, 'Y402H') with risk of AMD among studies with differing study designs, participant ancestry and AMD grade and to investigate effect modification by smoking, we report two unpublished genetic association studies (n = 2759) combined with data from 24 published studies (26 studies, 26,494 individuals, including 14,174 cases of AMD) of European ancestry, 10 of which provided individual-level data used to test gene-smoking interaction; and 16 published studies from non-European ancestry.

RESULTS

In individuals of European ancestry, there was a significant association between Y402H and late-AMD with a per-allele odds ratio (OR) of 2.27 [95% confidence interval (CI) 2.10-2.45; P = 1.1 x 10(-161)]. There was no evidence of effect modification by smoking (P = 0.75). The frequency of Y402H varied by ancestral origin and the association with AMD in non-Europeans was less clear, limited by paucity of studies.

CONCLUSION

The Y402H variant confers a 2-fold higher risk of late-AMD per copy in individuals of European descent. This was stable to stratification by study design and AMD classification and not modified by smoking. The lack of association in non-Europeans requires further verification. These findings are of direct relevance for disease prediction. New research is needed to ascertain if differences in circulating levels, expression or activity of factor H protein explain the genetic association.

Pharmacogenetics and age-related macular degeneration

Pharmacogenetics seeks to explain interpatient variability in response to medications by investigating genotype-phenotype correlations. There is a small but growing body of data regarding the pharmacogenetics of both nonexudative and exudative age-related macular degeneration. Most reported data concern polymorphisms in the complement factor H and age-related maculopathy susceptibility 2 genes. At this time, the data are not consistent and no definite conclusions may be drawn. As clinical trials data continue to accumulate, these relationships may become more apparent.

Age-related macular degeneration-susceptibility single nucleotide polymorphisms in a han chinese control population

PURPOSE

Our study aimed to detect the frequency of age-related macular degeneration (AMD)-susceptibility single nucleotide polymorphisms (SNPs) in control subjects of Han Chinese in a population-based study.

METHODS

A total of 419 subjects of Han Chinese without AMD were recruited from our population-based Nantong Eye Study. Nine AMD-susceptibility SNPs were genotyped. The allele/genotype frequencies were compared with the data from the literature and NCBI Reference Assembly.

RESULTS

The call rates of genotyping were > 98%. All tested SNPs except for HTRA1 rs11200638 were in Hardy-Weinberg Equilibrium (HWE). The allele distributions of some AMD-susceptibility SNPs were different from the records for the Chinese population in the National Center for Biotechnology Information (NCBI) Reference Assembly. Compared to those in a Caucasian population, the frequency of minor alleles of CFH rs800292 (48% vs. 19.2%) and HTRA1 rs11200638 were much higher (47% vs. 25%), while the frequency of minor alleles of CFH rs1061170 (9% vs. 35%), CX3CR1 rs3732379 (3% vs. 21%), CX3CR1 rs3732378 (3% vs. 11%) and SERPING1 rs2511989 (11% vs. 48%) were much lower in the Han Chinese population. Minor differences were observed in the frequency of minor alleles of CFB rs4151667, C2 rs547154 and TLR3 rs3775291. The allele/genotype frequencies of CFH rs1061170 and HTRA1 rs11200638, two well-confirmed AMD-susceptible SNPs, were close to each other in the Han Chinese and Japanese population.

CONCLUSION

The distribution of AMD-susceptibility SNPs shows ethnicity specificity. Substantial differences of the SNPs' distribution were noted from study to study, even within the same ethnic group. The genotype data will be used for longitudinal observation of AMD onset in the follow-up of the cohort.

Analysis of complement factor H Y402H, LOC387715, HTRA1 polymorphisms and ApoE alleles with susceptibility to age-related macular degeneration in Hungarian patients

PURPOSE

Recent studies strongly support the role of genetic factors in the aetiology of age-related macular degeneration (AMD). We investigated the frequency of Tyr402His polymorphism of the complement factor H (CFH) gene, Ser69Ala polymorphism at LOC387715, rs11200638 polymorphism of the HTRA1 gene and different apolipoprotein E (ApoE) alleles in Hungarian patients with AMD in order to determine the disease risk conferred by these factors.

METHODS

In a case-control study, we performed clinical and molecular genetic examination of 105 AMD patients (48 patients in the early and 57 in the late subgroup) and 95 unrelated healthy controls. Detailed patient histories were recorded with the use of a questionnaire focusing on known risk factors for AMD.

RESULTS

In the early AMD subgroup, homozygous CFH, LOC387715 or HTRA1 polymorphisms conferred a 4.9-fold (95% confidence interval [CI] 1.7-14.2), 7.4-fold (95% CI 2.1-26.2) or 10.1-fold (95% CI 2.5-40.8) risk of disease, respectively. In the late AMD subgroup, carriers of two CFH, LOC387715 or HTRA1 risk alleles were at 10.7-fold (95% CI 3.7-31.0), 11.3-fold (95% CI 3.2-40.4) or 13.5-fold (95% CI 3.3-55.4) greater disease risk, respectively. Two CFH and one LOC387715 risk alleles in combination conferred a 15.0-fold (95% CI 3.2-71.0) increase in risk, whereas two LOC387715 risk alleles combined with one CFH risk allele was associated with a 14.0-fold (95% CI 2.1-95.1) increased risk for late AMD. ApoE alleles neither increased disease risk nor proved to be protective.

CONCLUSIONS

The CFH, LOC387715 and HTRA1 polymorphisms are strongly associated with the development of AMD in the Hungarian population. The association is particularly pronounced when homozygous risk alleles are present and in the late stages of the disease.

Association between the SERPING1 gene and age-related macular degeneration and polypoidal choroidal vasculopathy in Japanese

PURPOSE

Recently, a complement component 1 inhibitor (SERPING1) gene polymorphism was identified as a novel risk factor for age-related macular degeneration (AMD) in Caucasians. We aimed to investigate whether variations in SERPING1 are associated with typical AMD or with polypoidal choroidal vasculopathy (PCV) in a Japanese population.

METHODS

We performed a case-control study in a group of Japanese patients with typical AMD (n = 401) or PCV (n = 510) and in 2 independent control groups--336 cataract patients without age-related maculopathy and 1,194 healthy Japanese individuals. Differences in the observed genotypic distribution between the case and control groups were tested using chi-square test for trend. Age and gender were adjusted using logistic regression analysis.

RESULTS

We targeted rs2511989 as the haplotype-tagging single nucleotide polymorphism (SNP) for the SERPING1 gene, which was reported to be associated with the risk of AMD in Caucasians. Although we compared the genotypic distributions of rs2511989 in typical AMD and PCV patients against 2 independent control groups (cataract patients and healthy Japanese individuals), SERPING1 rs2511989 was not significantly associated with typical AMD (P = 0.932 and 0.513, respectively) or PCV (P = 0.505 and 0.141, respectively). After correction for age and gender differences based on a logistic regression model, the difference in genotypic distributions remained insignificant (P>0.05). Our sample size had a statistical power of more than 90% to detect an association of a risk allele with an odds ratio reported in the original studies for rs2511989 for developing AMD.

CONCLUSIONS

In the present study, we could not replicate the reported association between SERPING1 and either neovascular AMD or PCV in a Japanese population; thus, the results suggest that SERPING1 does not play a significant role in the risk of developing AMD or PCV in Japanese.

Association of complement factor H Y402H polymorphism and age-related macular degeneration in Brazilian patients

PURPOSE

The aim of this study was investigate the association between complement Factor H polymorphism (Y402H) and age-related macular degeneration (AMD) in Brazilian patients.

METHODS

Patients with AMD aged 50 or more and age-matched healthy controls were enrolled in the study. Genomic DNA was isolated from leucocytes of patients and controls; the Y402H polymorphism of complement Factor H gene (CFH) was determined by polymerase chain reaction directed sequencing.

RESULTS

The frequency of 1277C allele of Factor H was 56.30% in patients with AMD compared with 36.51% in controls (p-value=0.001). The genotypic distribution differed significantly between the two groups (1277CC 36.98%, 1277CT 38.65% and 1277TT 24.37% for AMD group; 1277CC 13.16%, 1277CT 46.71% and 1277TT 40.13% for controls, p-value=0.001). The odds ratio for patients with AMD carrying only one 1277C allele was 1.36 and for those carrying two 1277C alleles was 4.63, when compared to the control group.

CONCLUSIONS

These results suggest the Y402H polymorphism of CFH is a risk factor to the development of AMD in Brazilian patients. This is in accordance with findings from the majority of previous study population in Europe and North American.

Phenotype and genotype characteristics of age-related macular degeneration in a Japanese population

PURPOSE

To describe phenotype and genotype characteristics of age-related macular degeneration (AMD) in Japanese patients.

DESIGN

A case-control study.

PARTICIPANTS

A total of 550 case-control samples composed of 408 consecutive AMD cases and 142 controls.

METHODS

Clinical information assessing age, gender, affected eyes, fundus features, and fluorescein/indocyanine green angiograms were systematically evaluated. Four single nucleotide polymorphisms (SNPs; rs800292, rs1061170, rs1410996, rs2274700) in the complement factor H (CFH) gene, 1 SNP (rs11200638) in the high-temperature requirement factor A1 (HTRA1) gene, 3 SNPs (rs699947, rs1570360, rs2010963) in the vascular endothelial growth factor (VEGF) gene, and 4 SNPs (rs12150053, rs12948385, rs9913583, rs1136287) in the pigment epithelium-derived factor (PEDF) gene were assessed using TaqMan technology.

MAIN OUTCOME MEASURES

The clinical phenotype information and genotypes of CFH, HTRA1, VEGF, and PEDF polymorphisms.

RESULTS

Of Japanese patients with neovascular AMD (nAMD), 219 (58.7%) had typical nAMD and 154 (41.3%) had polypoidal choroidal vasculopathy (PCV). The frequency of bilateral exudative involvement was similar between typical nAMD (15.5%) and PCV (13.6%) (P = 0.613). Significant soft drusen were observed in the fellow eyes of 88 (47.6%) of 185 patients with unilateral typical nAMD and in 25 (18.8%) of 133 patients with unilateral PCV (P = 1.24x10(-7)). A serous pigment epithelium detachment was seen in 55 (25.1%) of 219 patients with typical nAMD and in 64 (41.6%) of 154 patients with PCV. A significant association was noted in CFH-rs800292, CFH-rs1410996, CFH-rs2274700, and HTRA1-rs11200638 with AMD development (P = 2.36x10(-5), 7.18x10(-5), 7.18x10(-5), 2.70x10(-7), respectively; population attributable risk = 57.3%, 57.8%, 57.8%, and 58.9%, respectively). We estimated the highest-risk group to have an approximately 70-fold greater risk of nAMD compared with the lowest-risk group when analyzing a combination of 4 SNPs in the CFH and HTRA1 genes.

CONCLUSIONS

The Japanese AMD phenotype is characterized by a higher frequency of PCV, male predominance, and lower frequency of bilateral presentation compared with Caucasian AMD. Genotype analyses demonstrate a significant population attributable risk for SNPs in the CFH and HTRA1 genes and demonstrate joint effects for both genes. Gene variants in both CFH and HTRA1 contribute significantly to the AMD phenotype in a Japanese population.

An ecological correlation study of late age-related macular degeneration and the complement factor H Y402H polymorphism

PURPOSE

To investigate whether variation in the distribution of the risk allele frequency of the Y402H single-nucleotide polymorphism (SNP) across various ethnicities and geographic regions reflects differences in the prevalence of late age-related macular degeneration (AMD) in those ethnicities.

METHODS

Published data were obtained via a systematic search. Study samples were grouped into clusters by ethnicity and geographic location and the Spearman correlation coefficient of the prevalence of late AMD and risk allele frequencies was calculated across clusters.

RESULTS

Across all ethnicities, AMD prevalence was seen to increase with age. Populations of European descent had both higher risk allele frequencies and prevalence of late AMD than did Japanese, Chinese, and Hispanic descendants. Results for African descendants were anomalous: although allele frequency was similar to that in European populations, the age-specific prevalence of late AMD was considerably lower. The correlation coefficient for the association between allele frequency and AMD prevalence was 0.40 (95% confidence interval [CI] = -0.36 to 0.84, P = 0.28) in all populations combined and 0.71 (95% CI = 0.02-0.94, P = 0.04) when people of African descent were excluded.

CONCLUSIONS

Evidence was found at the population level to support a positive association between the Y204H risk allele and the prevalence of AMD after exclusion of studies undertaken on persons of African ancestry. Data in African, Middle Eastern, and South American populations are needed to provide a better understanding of the association of late AMD genetic risk across ethnicities.

Complement factor H and LOC387715 gene polymorphisms in a Greek population with age-related macular degeneration

BACKGROUND

Age-related macular degeneration (AMD) is the leading cause of severe visual loss among people over 60 years old. The lack of a broadly effective treatment for AMD underscores the need to identify causative biomarkers that could serve as preventive targets. Thus far, two major susceptibility loci for AMD have been identified, CFH T1277C and LOC387715 G270T. The primary goal of the present study was to elucidate whether these polymorphisms are major genetic determinants of AMD in a Greek population.

PATIENTS AND METHODS

A clinic-based, case-control association study was conducted, comprising 100 Greek patients with early and late-stage AMD and 115 independent controls of Caucasian origin. All participants underwent clinical examination including best-corrected visual acuity, intraocular pressure, and dilated fundus examination. Moreover, they were genotyped for CFH T1277C and LOC387715 G270T polymorphisms, by direct sequencing and ARMS PCR, respectively.

RESULTS

The frequency of the CFH 1277C allele was significantly higher in AMD patients in comparison with controls while the odds ratios (ORs) for AMD were 4.4-5.5. Statistical comparison of early and advanced AMD patients, on the basis of CFH genotype, revealed that the CFH 1277C allele was associated with both subgroups when compared with the controls (P < 0.001). When statistical comparison was performed between early and advanced patients on the basis of CFH genotypic frequencies, the CC genotype was found to be more prevalent in advanced AMD patients (P = 0.008, OR = 2.3). The frequency of the LOC387715 270 T allele was higher in AMD patients in comparison with controls (P < 0.04) while the ORs for AMD were 1.4-2. No statistically significant differences were located between the early AMD patients and controls, on the basis of LOC387715 genotype (P = 0.189). On the contrary, the T270G polymorphism was associated with advanced AMD (P = 0.04). Moreover, the TT genotype was more prevalent in patients with advanced AMD (P = 0.011, OR = 1.7) when compared with early AMD patients. Assessment of the combined contribution of CFH T1277C and LOC387715 G270T SNPs showed an independent manner of action of these polymorphisms in the development of the disease.

CONCLUSIONS

The replication of the reported associations of CFH T1277C polymorphism with AMD suggest that the 1277C allele could serve as a high-risk genetic marker for the development of AMD and the progression of the disease to the advanced clinical stage in the Greek population.

Complement factor H variant increases the risk for early age-related macular degeneration

PURPOSE

To investigate whether a polymorphism in the complement factor H gene determines the risk for the development of early age-related macular degeneration (AMD).

METHODS

In this retrospective case-control study, we enrolled 133 unrelated Taiwan Chinese patients with early AMD and 180 age- and sex-matched control subjects. Early AMD was defined as the presence of extensive intermediate drusen or any large, soft drusen (> or = 125 microm), possibly accompanied by drusenoid retinal pigment epithelial detachment, and the absence of signs of late AMD. Genomic DNA was extracted from peripheral blood obtained from all the AMD patients and control subjects. Polymerase chain reaction was performed to analyze the complement factor H polymorphism (Y402H, rs1061170).

RESULTS

The genotype distribution differed significantly between the early AMD patients (TT 80%; TC 14%; and CC 6%) and controls (TT 91%; TC 9%; CC 0%; P = 9 x 10(-4)). The C allele frequency was significantly higher in the early AMD patients than in the controls (13% vs. 4%, P = 1 x 10(-4), odds ratios = 3.26, 95% confidence intervals = 1.76-6.02).

CONCLUSIONS

Our study demonstrated that the presence of the Y402H polymorphism in complement factor H is significantly associated with increased susceptibility to early AMD in Taiwan Chinese populations and that the C allele frequency is low in these populations.

Multifactor effects and evidence of potential interaction between complement factor H Y402H and LOC387715 A69S in age-related macular degeneration

Background

Variants in the complement cascade genes and the LOC387715/HTRA1, have been widely reported to associate with age-related macular degeneration (AMD), the most common cause of visual impairment in industrialized countries.

Methods/Principal Findings

We investigated the association between the LOC387715 A69S and complement component C3 R102G risk alleles in the Finnish case-control material and found a significant association with both variants (OR 2.98, p = 3.75×10⁻⁹; non-AMD controls and OR 2.79, p = 2.78×10⁻¹⁹, blood donor controls and OR 1.83, p = 0.008; non-AMD controls and OR 1.39, p = 0.039; blood donor controls), respectively. Previously, we have shown a strong association between complement factor H (CFH) Y402H and AMD in the Finnish population. A carrier of at least one risk allele in each of the three susceptibility loci (LOC387715, C3, CFH) had an 18-fold risk of AMD when compared to a non-carrier homozygote in all three loci. A tentative gene-gene interaction between the two major AMD-associated loci, LOC387715 and CFH, was found in this study using a multiplicative (logistic regression) model, a synergy index (departure-from-additivity model) and the mutual information method (MI), suggesting that a common causative pathway may exist for these genes. Smoking (ever vs. never) exerted an extra risk for AMD, but somewhat surprisingly, only in connection with other factors such as sex and the C3 genotype. Population attributable risks (PAR) for the CFH, LOC387715 and C3 variants were 58.2%, 51.4% and 5.8%, respectively, the summary PAR for the three variants being 65.4%.

Conclusions/Significance

Evidence for gene-gene interaction between two major AMD associated loci CFH and LOC387715 was obtained using three methods, logistic regression, a synergy index and the mutual information (MI) index.

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.

C2 and CFB genes in age-related maculopathy and joint action with CFH and LOC387715 genes

Background

Age-related maculopathy (ARM) is a common cause of visual impairment in the elderly populations of industrialized countries and significantly affects the quality of life of those suffering from the disease. Variants within two genes, the complement factor H (CFH) and the poorly characterized LOC387715 (ARMS2), are widely recognized as ARM risk factors. CFH is important in regulation of the alternative complement pathway suggesting this pathway is involved in ARM pathogenesis. Two other complement pathway genes, the closely linked complement component receptor (C2) and complement factor B (CFB), were recently shown to harbor variants associated with ARM.

Methods/Principal Findings

We investigated two SNPs in C2 and two in CFB in independent case-control and family cohorts of white subjects and found rs547154, an intronic SNP in C2, to be significantly associated with ARM in both our case-control (P-value 0.00007) and family data (P-value 0.00001). Logistic regression analysis suggested that accounting for the effect at this locus significantly (P-value 0.002) improves the fit of a genetic risk model of CFH and LOC387715 effects only. Modeling with the generalized multifactor dimensionality reduction method showed that adding C2 to the two-factor model of CFH and LOC387715 increases the sensitivity (from 63% to 73%). However, the balanced accuracy increases only from 71% to 72%, and the specificity decreases from 80% to 72%.

Conclusions/Significance

C2/CFB significantly influences AMD susceptibility and although accounting for effects at this locus does not dramatically increase the overall accuracy of the genetic risk model, the improvement over the CFH-LOC387715 model is statistically significant.

The effect of complement factor H Y402H polymorphism on the outcome of photodynamic therapy in age-related macular degeneration

PURPOSE

Photodynamic therapy (PDT) has been widely used in the treatment of age-related macular degeneration (AMD). The complement cascade has an important role in the tissue reactions occurring after PDT. The Y402H polymorphism of the complement factor H (CFH) gene has been identified as a risk factor for AMD. Since CFH is central in the regulation of the complement system the authors wanted to analyze whether the CFH Y402H polymorphism modifies the PDT outcome in AMD.

METHODS

A total of 88 patients having been treated with PDT and without further scheduled PDT sessions were analyzed. Depending on the situation at their final PDT session the patients were classified retrospectively as PDT-responders or PDT-nonresponders. All patients were genotyped for the CFH Y402H polymorphism.

RESULTS

The proportion of PDT-responders was 18/26 (69.2%) in patients homozygous for the CFH Y402H risk allele, 34/50 (68.0%) in heterozygous, and 7/12 (58.3%) in patients with the normal genotype (p=0.520). The median number of PDT treatments of the PDT-responders was three for all the genotypes.

CONCLUSIONS

The dysfunction of the CFH related to the risk of AMD and caused by the Y402H polymorphism does not modify the outcome of PDT. Genotyping for CFH Y402H cannot be used to select patients for this treatment.

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

PURPOSE

To determine whether the complement factor H (CFH) Y402H variant is associated with specific age-related macular degeneration (AMD) clinical phenotypes.

DESIGN

Retrospective, case-control study.

METHODS

One hundred and eighty-eight white subjects with AMD and 189 control subjects were genotyped for the T-to-C polymorphism in exon 9 of the CFH gene by restriction-fragment length analysis and deoxyribonucleic acid (DNA) sequencing using genomic DNA from mouthwash samples. AMD phenotypes were characterized by clinical examination, fundus photography, and fluorescein angiography.

RESULTS

Heterozygosity for the at-risk genotype (TC) increased the likelihood for AMD 2.1-fold (95% confidence interval [CI], 1.3 to 3.3), whereas homozygosity for the genotype (CC) increased the likelihood for AMD 6.5-fold (95% CI, 3.4 to 12.5) in our population. The C allele was associated significantly with predominantly classic choroidal neovascularization (odds ratio [OR], 2.01; 95% CI, 1.34 to 3.30). Neovascular lesion size was similar among the three genotypes (P = .67).

CONCLUSIONS

The Y402H CFH variant carried a significantly increased risk for developing AMD in our population. Genotype and phenotype correlations regarding choroidal neovascular lesion type were observed.

Progress in defining the molecular biology of age related macular degeneration

Age related macular degeneration (AMD) is an extremely prevalent complex genetic disorder. Its incidence rises exponentially in the elderly to a frequency of 1 in 2 in the general population by age 85. It affects approximately 25 million people and is the commonest cause of irreversible visual loss in the Western world. It is therefore a major public health problem. However, until recently its aetiology was unknown. Our understanding of both the molecular biology of AMD and the relevant clinical treatments has progressed dramatically in the last 2 years. Two genes of large effect have been identified which together contribute to over 70% of the population attributable risk of AMD. Treatments which inhibit expression of vascular endothelial growth factor have been developed which can rescue vision in the "wet" form of the disease. The association of complement factor H with AMD highlights the importance of the alternative complement pathway in the development of AMD whilst the pathophysiology of the serine protease HTRA1 is now under intensive study. This review will give an insight into these developments and will summarise our current knowledge of the molecular biology of AMD.

Role of genetic factors and inflammation in age-related macular degeneration

Complement factor H (CFH) has been implicated in the predisposition to advanced forms of age-related macular degeneration (AMD). The purpose of this review is to highlight recent discoveries implicating single nucleotide polymorphisms on 1q32, 6p21, and 10q26 in the risk for development of AMD. In addition, the central role of CFH in the complement cascade and its role in the inflammatory hypothesis for AMD are reviewed.

A polymorphism of LOC387715 gene is associated with age-related macular degeneration in the Japanese population

Age-related macular degeneration (AMD) is one of the leading causes of blindness among older adults in developed countries and also in Japan. Previous research suggests that AMD is etiologically a complex disease, caused by multiple genes and environmental factors. Association studies have identified that a complement factor H gene (CFH) variant is a major risk factor for AMD in Caucasians. However, we and two other groups have reported no association between CFH and AMD in the Japanese population. Recent studies have suggested that LOC387715 on chromosome 10q26 may be the second major risk loci for AMD in Caucasians. In this study, we examined the association between LOC387715 and AMD in Japanese, and our results show that polymorphism of the LOC387715 gene is associated with AMD in Japanese as well as in Caucasians. Our data show a disease odds ratio of 6.20 (95% CI: 2.87-13.40) conferred by homozygosity for risk alleles at LOC387715 compared with the non-risk genotype. A polymorphism of LOC387715 gene is associated with AMD in the Japanese population.