Gene-gene interaction of CFH, ARMS2, and ARMS2/HTRA1 on the risk of neovascular age-related macular degeneration and polypoidal choroidal vasculopathy in Chinese population

Potential of Long Non-Coding RNAs in Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of visual impairment in the aging population with poorly known pathogenesis and lack of effective treatment. Age and family history are the strongest AMD risk factors, and several loci were identified to contribute to AMD. Recently, also the epigenetic profile was associated with AMD, and some long non-coding RNAs (lncRNAs) were shown to involve in AMD pathogenesis. The Vax2os1/2 (ventral anterior homeobox 2 opposite strand isoform 1) lncRNAs may modulate the balance between pro- and anti-angiogenic factors in the eye contributing to wet AMD. The stress-induced dedifferentiation of retinal pigment epithelium cells can be inhibited by the ZNF503-AS1 (zinc finger protein 503 antisense RNA 2) and LINC00167 lncRNAs. Overexpression of the PWRN2 (Prader-Willi region non-protein-coding RNA 2) lncRNA aggravated RPE cells apoptosis and mitochondrial impairment induced by oxidative stress. Several other lncRNAs were reported to exert protective or detrimental effects in AMD. However, many studies are limited to an association between lncRNA and AMD in patients or model systems with bioinformatics. Therefore, further works on lncRNAs in AMD are rational, and they should be enriched with mechanistic and clinical studies to validate conclusions obtained in high-throughput in vitro research.

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

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

Development of an automated system for the detection of genotype in polypoidal choroidal vasculopathy using retinal image phenotype

BACKGROUND AND OBJECTIVES

Polypoidal choroidal vasculopathy (PCV) is a retinal disorder characterized by the presence of aneurismal polypoidal lesions in the choroidal vasculature. A single nucleotide polymorphism (SNP) is a common genetic variant which may be associated with the disease. This study is to investigate the association of HERPUD1 (rs2217332) gene with PCV in the Indian population and develop an automated system for genotype and phenotype correlation using fundus images and machine learning methods.

METHODS

A cohort of 54 PCV patients and 120 control subjects were recruited for the study. Genotyping of SNP (HERPUD1, rs2217332) was performed by following polymerase chain reaction and direct sequencing method. Statistical association of SNP to PCV was determined using chi-square analysis. The acquired GG and AG images were preprocessed using an adaptive histogram. 19 and 18 texture features were extracted from the images in the PCV naïve cases and PCV patients on treatment, respectively. Student's independent t-test was then employed for the selection of significant features, which were input to the ensemble tree for automated classification. Leave-one-out validation was used to evaluate the system.

RESULTS

HERPUD1 rs2217332 SNP is significantly associated in PCV patients compared to control (P = 0.0296, odds ratio [OD] = 2.297, 95% confidence interval [CI] = 1.087-4.856) in the Indian population. High F1 and precision values of 85.71%, 86.84% and 85.71%, 93.75% were achieved in the pre and post- treatment phases, respectively.

CONCLUSION

Our results suggest that the HERPUD1 polymorphism is associated in PCV patients. Based on our analysis, it may be possible to predict the genotype and disease status of PCV patients using fundus images in assistance with a machine learning algorithm.

The association of polypoidal choroidal vasculopathy clinical phenotypes with previously reported genetic markers

PURPOSE

Genetic studies have identified the association of some single-nucleotide polymorphisms (SNPs) with polypoidal choroidal vasculopathy (PCV), but little is known about whether these SNPs are related to PCV clinical features as well. We performed this study to examine the association of 12 SNPs with PCV clinical phenotypes.

METHODS

Sixty-nine PCV eyes of 69 patients were included. Genomic DNA was extracted from peripheral blood. Agilent SureSelect Human ALL Exon V6 was used to sequence the 12 SNPs previously reported to associate with PCV. Baseline best-corrected visual acuity (BCVA), sub-foveal choroidal thickness (SFCT), choroid maximum vascular diameter (MVD), choroidal vascular hyperpermeability (CVH), and greatest linear dimension (GLD) of entire lesion were measured and compared between patients of different genotypes. Fisher's exact test and Mann-Whitney U test were mainly used to compare categorical variables and continuous variables respectively.

RESULTS

HTRA1 rs2293870 was a protective factor of PCV or AMD in the fellow eye (P = 0.040) and was related with greater SFCT in PCV eye after multiple linear regression (P = 0.043). C3 rs17030 was associated with smaller GLD (P = 0.033). CFH rs2274700 was related to lower MVD (P = 0.043) and was a protective factor for CVH (P = 0.034).

CONCLUSION

Multiple PCV-associated SNPs are associated with PCV clinical phenotypes. The involvement of several synonymous SNPs calls for further research on the role of transcriptional alterations and trans-regulation of distant signaling pathways in PCV pathogenesis.

Association between CFH single nucleotide polymorphisms and response to photodynamic therapy in patients with central serous chorioretinopathy

PURPOSE

To evaluate the association between single nucleotide polymorphisms (SNPs) in the complement factor H (CFH) gene and response to PDT in patients with CSC.

METHODS

103 eyes from 93 patients with CSC were enrolled from Department of Ophthalmology of the People's Hospital Peking University. Genotyping for selected SNPs in the CFH gene was performed, and multivariate linear analysis was used to identify factors influencing PDT treatment outcomes. Genetics associations between SNPs in the CFH gene and response to PDT in patients with CSC were analyzed.

RESULTS

None of the seven SNPs examined in this study (rs800292, rs1061170, rs3753394, rs3753396, rs2284664, rs1329428, and rs1065489) showed significant associations with 1-month outcomes after PDT in patients with CSC (P > 0.05). Baseline BCVA changed at 1 month after PDT (P < 0.001), and baseline retinal thickness was associated with changes in retinal thickness at 1 month after PDT (P < 0.001). Age was significantly associated with resolution of SRF at 1 month after PDT (P = 0.004).

CONCLUSIONS

There were no significant associations between SNPs in the CFH gene and 1-month outcomes after PDT in patients with CSC. However, baseline BCVA, baseline retinal thickness, and age were significantly associated with response to PDT in patients with CSC. Larger studies with more power are necessary to further determine whether an association exists between SNPs in the CFH gene and PDT in patients with CSC.

Genetic factors for idiopathic choroidal neovascularization

Objective: The aim of this study was to investigate genetic factors associated with idiopathic choroidal neovascularization (ICNV). Methods: We conducted a case-control study including 69 cases with ICNV and 114 controls who underwent cataract surgery. Single nucleotide polymorphisms (SNPs) from genes reported to be related to AMD, CNV and uveitis were selected for this study. Results: In an univariate analysis, the rs669676 SNP located in the COL8A1 gene was associated with the proportion of people who has idiopathic CNV ( X2 = 9.3453, corrected p-value = 0.1). For the rs669676 SNP, minor allele homozygotes, in the dominant model of genotype analysis (GG versus AA-GA), it showed significant differences in the ICNV group vs controls (p = .01, OR = 1.219 (95%CI: 1.04-1.429)). Conclusions: The rs669676 SNP located in the COL8A1 gene may contribute to a genetic susceptibility for ICNV.

Association Between Complement Factor C2/C3/CFB/CFH Polymorphisms and Age-Related Macular Degeneration: A Meta-Analysis

BACKGROUND

Several previous studies have assessed the contribution of polymorphisms in genes encoding the complement factors C2/C3/CFB/CFH with the risk of age-related macular degeneration (AMD), however the results have been inconsistent. We conducted a meta-analysis to systematically review the potential association between complement factor polymorphisms and AMD.

METHODS

Studies that investigated associations between C2 (rs547154 and rs9332739), C3 (rs1047286), CFB (rs4151667 and rs641153), and CFH (rs551397 and rs2274700) polymorphisms and AMD were identified by searching PubMed, EMBASE, Web of Science, and Cochrane Library databases for articles published prior to January 1, 2018. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated to evaluate the association between these polymorphisms and AMD using Stata 12.0 software. Q and I² statistics were used to evaluate between-study heterogeneity. Publication bias analyses were conducted using Begg's test. We also conducted an ethnic subgroup analysis.

RESULTS

A total of 53 studies that included data for 53,774 patients and 56,973 healthy controls were evaluated. The pooled ORs for rs551397, rs2274700, rs4151667, rs641153, rs1047286, rs9332739, and rs547154 in the heterozygote model were 0.53 (95% CI: 0.45-0.61), 0.53 (95% CI: 0.40-0.70), 0.54 (95% CI: 0.46-0.63), 0.48 (95% CI: 0.4-0.57), 1.42 (95% CI: 1.22-1.66), 0.5 (95% CI: 0.45-0.56), and 0.52 (95% CI: 0.43-0.62), respectively.

CONCLUSION

Our findings from this analysis confirmed the protective role of C2/CFB/CFH polymorphisms in the development of AMD, but showed that the single nucleotide polymorphism in C3 was a high-risk factor for AMD. The racial analysis results suggested that the effect of variant alleles was stronger in Caucasians than Asians.

Genetic modifiers as relevant biological variables of eye disorders

From early in the study of mammalian genetics, it was clear that modifiers can have a striking influence on phenotypes. Today, several modifiers have now been studied in enough detail to allow a glimpse of how they function and influence our perspective of disease. With respect to diseases of the eye, some modifiers are an important source of phenotypic variation that can elucidate how genes function in networks to collectively shape ocular anatomy and physiology, thus influencing our understanding of basic biology. Other modifiers represent an opportunity for new therapeutic targets, whose manipulation could be used to mitigate ophthalmic disease. Here, we review progress in the study of genetic modifiers of eye disorders, with examples from mice and humans that together illustrate the ubiquitous nature of genetic modifiers and why they are relevant biological variables in experimental design. Special emphasis is given to ophthalmic modifiers in mice, especially those relevant to selection of genetic background and those that might inadvertently be a source of experimental variability. These modifiers are capable of influencing interpretations of many experiments using targeted genome manipulations such as knockouts or transgenics. Whereas there are fewer examples of modifiers of eye disorders in humans with a molecular identification, there is ample evidence that they exist and should be considered as a relevant biological variable in human genetic studies as well.

AMD Genetics in India: The Missing Links

Age related macular degeneration is a disease which occurs in aged individuals. There are various changes that occur at the cellular, molecular and physiological level with advancing age (Samiec et al., 1988; Sharma K. et al., 2014). Drusen deposition between retinal pigment epithelium (RPE) and Bruch’s membrane (BM) is one of the key features in AMD patients (Mullins et al., 2000; Hageman et al., 2001) similar to Aβ/tau aggregates in Alzheimer’s disease (AD) patients. The primary goal of this review is to discuss whether the various candidate genes and associated biomarkers, that are known to play an independent role in progression of AMD, exert deleterious effect on phenotype, alone or in combination, in Indian AMD patients from the same ethnic group and the significance of such research. A statistical model for probable interaction between genes could be derived from such analysis. Therefore, one can use multiple modalities to identify and enrol AMD patients based on established clinical criteria and examine the risk factors to determine if these genes are associated with risk factors, biomarkers or disease by Mendelian randomization. Similarly, there are large numbers of single nucleotide polymorphisms (SNPs) identified in human population. Even non-synonymous SNPs (nsSNPs) are believed to induce deleterious effects on the functionality of various proteins. The study of such snSNPs could provide a better genetic insight for diverse phenotypes of AMD patients, predicting significant risk factors for the disease in Indian population. Therefore, the prediction of biological effect of nsSNPs in the candidate genes and the associated grant applications in the subject are highly solicited.Therefore, genotyping and levels of protein expression of various genes would provide wider canvas in genetic complexity of AMD pathology which should be evaluated by valid statistical and bioinformatics’ tools. Longitudinal follow up of Indian AMD patients to evaluate the temporal effect of SNPs and biomarkers on progression of disease would provide a unique strategy in the field.