Analysis of hemopexin plasma levels in patients with age-related macular degeneration

Purpose

A protein quantitative trait locus (pQTL) analysis recently revealed a strong association between hemopexin (HPX) levels and genetic variants at the complement factor H (CFH) locus. In this study, we aimed to determine HPX plasma levels in patients with age-related macular degeneration (AMD) and to compare them with those in controls. We also investigated whether genetic variants at the CFH locus are associated with HPX plasma levels.

Methods

HPX levels were quantified in 200 advanced AMD cases and 200 controls using an enzyme-linked immunosorbent assay and compared between the two groups. Furthermore, HPX levels were analyzed per genotype group of three HPX-associated variants (rs61818956, rs10494745, and rs10801582) and four AMD-associated variants (rs794362 [proxy for rs187328863], rs570618, rs10922109, and rs61818924 [proxy for rs61818925]) at the CFH locus.

Results

HPX levels were similar in the control group compared with the AMD group. The three variants at the CFH locus, which were previously associated with the HPX levels, showed no association with the HPX levels in our data set. No significant differences in HPX levels were detected between the different genotype groups of AMD-associated variants at the CFH locus.

Conclusions

In this study, HPX levels were not associated with AMD or AMD-associated variants at the CFH locus. The finding of a previous pQTL study that variants at the CFH locus were associated with HPX levels was also not confirmed in this study.

Loss of the AMD-associated B3GLCT gene affects glycosylation of TSP1 without impairing secretion in retinal pigment epithelial cells

Age-related macular degeneration (AMD) has been associated with protective genetic variants in the β1-3 glucosyltransferase (B3GLCT) locus through genome-wide association studies. B3GLCT mediates modification of proteins with thrombospondin type I repeats (TSR) that contain O-linked glucose β1-3 fucose and C-linked mannose glycosylation motifs. B3GLCT-mediated modification is required for proper secretion of TSR-containing proteins. We aimed to start understanding the role of B3GLCT in AMD by evaluating its effect on glycosylation and secretion of proteins from retinal pigment epithelium (RPE) cells. We generated B3GLCT knockout (KO) RPE cells and analyzed glycosylation and secretion of thrombospondin 1 (TSP1), a protein involved in cellular processes highly relevant to AMD. Glycopeptide analysis confirmed the presence of the glucose-β1,3-fucose product of B3GLCT on TSP1 in wildtype (WT) cells and its absence in KO cells. C-mannosylation was variably present on WT TSP1 and increased on TSR domains 1 and 3 in KO cells. Secretion of TSP1 was not affected by the absence of B3GLCT, even not when TSP1 was upregulated by TNFα treatment or when TSP1 was overexpressed in HEK293T cells. Future research is needed to elucidate the effect of the observed glycosylation defects in the context of AMD, which might involve functional loss of TSP1 or effects on other TSR proteins.

Effect of rare coding variants in the CFI gene on Factor I expression levels

Factor I (FI) is one of the main inhibitors of complement activity, and numerous rare coding variants have been reported in patients with age-related macular degeneration, atypical hemolytic uremic syndrome and C3 glomerulopathy. Since many of these variants are of unknown clinical significance, this study aimed to determine the effect of rare coding variants in the complement factor I (CFI) gene on FI expression. We measured FI levels in plasma samples of carriers of rare coding variants and in vitro in the supernatants of epithelial cells expressing recombinant FI. FI levels were measured in 177 plasma samples of 155 individuals, carrying 24 different rare coding variants in CFI. In carriers of the variants p.Gly119Arg, p.Leu131Arg, p.Gly188Ala and c.772G>A (r.685_773del), significantly reduced FI plasma levels were detected. Furthermore, recombinant FI expression levels were determined for 126 rare coding variants. Of these variants 68 (54%) resulted in significantly reduced FI expression in supernatant compared to wildtype (WT). The recombinant protein expression levels correlated significantly with the FI level in plasma of carriers of CFI variants. In this study, we performed the most comprehensive FI expression level analysis of rare coding variants in CFI to date. More than half of CFI variants lead to reduced FI expression, which might impair complement regulation in vivo. Our study will aid the interpretation of rare coding CFI variants identified in clinical practice, which is in particular important in light of patient inclusion in ongoing clinical trials for CFI gene supplementation in AMD.

Micro-costing diagnostics in oncology: from single-gene testing to whole- genome sequencing

Purpose: Predictive diagnostics play an increasingly important role in personalized medicine for cancer treatment. Whole-genome sequencing (WGS)-based treatment selection is expected to rapidly increase worldwide. This study aimed to calculate and compare the total cost of currently used diagnostic techniques and of WGS in treatment of non-small cell lung carcinoma (NSCLC), melanoma, colorectal cancer (CRC), and gastrointestinal stromal tumor (GIST) in the Netherlands.Methods: The activity-based costing (ABC) method was conducted to calculate total cost of included diagnostic techniques based on data provided by Dutch pathology laboratories and the Dutch-centralized cancer WGS facility. Costs were allocated to four categories: capital costs, maintenance costs, software costs, and operational costs.Results: The total cost per cancer patient per technique varied from € 58 (Sanger sequencing, three amplicons) to € 2925 (paired tumor-normal WGS). The operational costs accounted for the vast majority (over 90%) of the total per cancer patient technique costs.Conclusion: This study outlined in detail all costing aspects and cost prices of current and new diagnostic modalities used in treatment of NSCLC, melanoma, CRC, and GIST in the Netherlands. Detailed cost differences and value comparisons between these diagnostic techniques enable future economic evaluations to support decision-making.

Complement Activation Levels Are Related to Disease Stage in AMD

Purpose

To study the levels of complement activation in different disease stages of AMD and the influence of genetic polymorphisms in complement genes.

Methods

We included 797 patients with AMD and 945 controls from the European Genetic Database. Patients were grouped into five AMD stages: early AMD, intermediate AMD, central geographic atrophy, active choroidal neovascularization or inactive choroidal neovascularization. Differences in complement activation, as defined by the systemic C3d/C3 ratio, between AMD stages were evaluated using general linear modeling. In addition, we evaluated the influence of 18 genetic AMD polymorphisms in complement genes and their effect on complement activation. Differences in complement activation between stages were evaluated stratifying by complement associated haplotypes.

Results

Complement activation levels differed significantly between AMD disease stages. As compared with controls, the C3d/C3 ratio was higher in patients with intermediate AMD (P < 0.001) and central geographic atrophy (P = 0.001). Two polymorphisms in CFH (rs10922109 and rs570618) and one in CFB (rs116503776) were significantly associated with complement activation. The association between AMD disease stage and complement activation was more pronounced in patients with haplotypes associated with the highest complement activation.

Conclusions

In general, consecutive AMD disease stages showed increasing levels of complement activation, especially in individuals with a genetic burden in complement genes. These findings contribute to the discussion on the pathogenesis of AMD in relation to complement activation and might suggest refinement in patient selection and the optimum window of treatment with complement inhibitors. Prospective studies are needed to confirm these results.

Major Predictive Factors for Progression of Early to Late Age-Related Macular Degeneration

INTRODUCTION

We present a prediction model for progression from early/intermediate to advanced age-related macular degeneration (AMD) within 5.9 years.

OBJECTIVES

To evaluate the combined role of genetic, nongenetic, and phenotypic risk factors for conversion from early to late AMD over ≥5 years.

METHODS

Baseline phenotypic characteristics were evaluated based on color fundus photography, spectral-domain optical coherence tomography, and infrared images. Genotyping for 36 single-nucleotide polymorphisms as well as systemic lipid and complement measurements were performed. Multivariable backward logistic regression resulted in a final prediction model.

RESULTS AND CONCLUSIONS

During a mean of 5.9 years of follow-up, 22.4% (n = 52) of the patients (n = 232) showed progression to late AMD. The multivariable prediction model included age, CFH variant rs1061170, pigment abnormalities, drusenoid pigment epithelial detachment (DPED), and hyperreflective foci (HRF). The model showed an area under the curve of 0.969 (95% confidence interval 0.948-0.990) and adequate calibration (Hosmer-Lemeshow test, p = 0.797). In addition to advanced age and carrying a CFH variant, pigment abnormalities, DPED, and HRF are relevant imaging biomarkers for conversion to late AMD. In clinical routine, an intensified monitoring of patients with a high-risk phenotypic profile may be suitable for the early detection of conversion to late AMD.

Increased circulating levels of Factor H-Related Protein 4 are strongly associated with age-related macular degeneration

Age-related macular degeneration (AMD) is a leading cause of blindness. Genetic variants at the chromosome 1q31.3 encompassing the complement factor H (CFH, FH) and CFH related genes (CFHR1-5) are major determinants of AMD susceptibility, but their molecular consequences remain unclear. Here we demonstrate that FHR-4 plays a prominent role in AMD pathogenesis. We show that systemic FHR-4 levels are elevated in AMD (P-value = 7.1 × 10-6), whereas no difference is seen for FH. Furthermore, FHR-4 accumulates in the choriocapillaris, Bruch's membrane and drusen, and can compete with FH/FHL-1 for C3b binding, preventing FI-mediated C3b cleavage. Critically, the protective allele of the strongest AMD-associated CFH locus variant rs10922109 has the highest association with reduced FHR-4 levels (P-value = 2.2 × 10-56), independently of the AMD-protective CFHR1-3 deletion, and even in those individuals that carry the high-risk allele of rs1061170 (Y402H). Our findings identify FHR-4 as a key molecular player contributing to complement dysregulation in AMD.

Genome-wide association analyses identify two susceptibility loci for pachychoroid disease central serous chorioretinopathy

The recently emerged pachychoroid concept has changed the understanding of age-related macular degeneration (AMD), which is a major cause of blindness; recent studies attributed AMD in part to pachychoroid disease central serous chorioretinopathy (CSC), suggesting the importance of elucidating the CSC pathogenesis. Our large genome-wide association study followed by validation studies in three independent Japanese and European cohorts, consisting of 1546 CSC samples and 13,029 controls, identified two novel CSC susceptibility loci: TNFRSF10A-LOC389641 and near GATA5 (rs13278062, odds ratio = 1.35, P = 1.26 × 10-13; rs6061548, odds ratio = 1.63, P = 5.36 × 10-15). A T allele at TNFRSF10A-LOC389641 rs13278062, a risk allele for CSC, is known to be a risk allele for AMD. This study not only identified new susceptibility genes for CSC, but also improves the understanding of the pathogenesis of AMD.

Functional analyses of rare genetic variants in complement component C9 identified in patients with age-related macular degeneration

Age-related macular degeneration (AMD) is a progressive disease of the central retina and the leading cause of irreversible vision loss in the western world. The involvement of abnormal complement activation in AMD has been suggested by association of variants in genes encoding complement proteins with disease development. A low-frequency variant (p.P167S) in the complement component C9 (C9) gene was recently shown to be highly associated with AMD; however, its functional outcome remains largely unexplored. In this study, we reveal five novel rare genetic variants (p.M45L, p.F62S, p.G126R, p.T170I and p.A529T) in C9 in AMD patients, and evaluate their functional effects in vitro together with the previously identified (p.R118W and p.P167S) C9 variants. Our results demonstrate that the concentration of C9 is significantly elevated in patients' sera carrying the p.M45L, p.F62S, p.P167S and p.A529T variants compared with non-carrier controls. However, no difference can be observed in soluble terminal complement complex levels between the carrier and non-carrier groups. Comparing the polymerization of the C9 variants we reveal that the p.P167S mutant spontaneously aggregates, while the other mutant proteins (except for C9 p.A529T) fail to polymerize in the presence of zinc. Altered polymerization of the p.F62S and p.P167S proteins associated with decreased lysis of sheep erythrocytes and adult retinal pigment epithelial-19 cells by carriers' sera. Our data suggest that the analyzed C9 variants affect only the secretion and polymerization of C9, without influencing its classical lytic activity. Future studies need to be performed to understand the implications of the altered polymerization of C9 in AMD pathology.

Role of the Complement System in Chronic Central Serous Chorioretinopathy: A Genome-Wide Association Study

Importance

To date, several targeted genetic studies on chronic central serous chorioretinopathy (cCSC) have been performed; however, unbiased genome-wide studies into the genetics of cCSC have not been reported. To discover new genetic loci associated with cCSC and to better understand the causative mechanism of this disease, we performed a genome-wide association study (GWAS) on patients with cCSC.

Objective

To discover new genetic loci and pathways associated with cCSC and to predict the association of genetic variants with gene expression in patients with cCSC.

Design, Setting, and Participants

This case-control GWAS was completed in the general community, 3 referral university medical centers, and outpatient care on Europeans individuals with cCSC and population-based control participants. Genotype data was collected from May 2013 to August 2017, and data analysis occurred from August 2017 to November 2017.

Main Outcomes and Measures

Associations of single-nucleotide polymorphisms, haplotypes, genetic pathways, and predicted gene expression with cCSC.

Results

A total of 521 patients with cCSC (median age, 51 years; interquartile range [IQR], 44-59 years; 420 [80.6%] male) and 3577 European population-based control participants (median age, 52 years; IQR, 37-71 years; 1630 [45.6%] male) were included. One locus on chromosome 1 at the complement factor H (CFH) gene reached genome-wide significance and was associated with an increased risk of cCSC (rs1329428; odds ratio [OR], 1.57 [95% CI, 1.38-1.80]; P = 3.12 × 10-11). The CFH haplotypes H1 and H3 were protective for cCSC (H1: OR, 0.64 [95% CI, 0.53-0.77]; P = 2.18 × 10-6; H3: OR, 0.54 [95% CI, 0.42-0.70]; P = 2.49 × 10-6), whereas haplotypes H2, H4, H5, and the aggregate of rare CFH haplotypes conferred increased risk (H2: OR, 1.57 [95% CI, 1.30-1.89]; P = 2.18 × 10-6; H4: OR, 1.43 [95% CI, 1.13-1.80]; P = 2.49 × 10-3; H5: OR, 1.80 [95% CI, 1.36-2.39]; P = 4.61 × 10-5; rare haplotypes: OR, 1.99 [95% CI, 1.43-2.77]; P = 4.59 × 10-5). Pathway analyses showed involvement of the complement cascade and alternative open reading frame (ARF) pathway in cCSC. Using PrediXcan, we identified changes in predicted expression of complement genes CFH, complement factor H related 1 (CFHR1), complement factor related 4 (CFHR4), and membrane cofactor protein (MCP/CD46). Additionally, the potassium sodium-activated channel subfamily T member 2 (KCNT2) and tumor necrosis factor receptor superfamily member 10a (TNFRSF10A) genes were differentially expressed in patients with cCSC.

Conclusions and Relevance

In this GWAS on cCSC, we identified a locus on chromosome 1 at the CFH gene that was significantly associated with cCSC, and we report protective and risk-conferring haplotypes in this gene. Pathway analyses were enriched for complement genes, and gene expression analysis suggests a role for CFH, CFHR1, CFHR4, CD46, KCNT2, and TNFRSF10A in the disease. Taken together, these results underscore the potential importance of the complement pathway in the causative mechanisms of cCSC.

Metabolomics in serum of patients with non-advanced age-related macular degeneration reveals aberrations in the glutamine pathway

Age-related macular degeneration (AMD) is a common, progressive multifactorial vision-threatening disease and many genetic and environmental risk factors have been identified. The risk of AMD is influenced by lifestyle and diet, which may be reflected by an altered metabolic profile. Therefore, measurements of metabolites could identify biomarkers for AMD, and could aid in identifying high-risk individuals. Hypothesis-free technologies such as metabolomics have a great potential to uncover biomarkers or pathways that contribute to disease pathophysiology. To date, only a limited number of metabolomic studies have been performed in AMD. Here, we aim to contribute to the discovery of novel biomarkers and metabolic pathways for AMD using a targeted metabolomics approach of 188 metabolites. This study focuses on non-advanced AMD, since there is a need for biomarkers for the early stages of disease before severe visual loss has occurred. Targeted metabolomics was performed in 72 patients with early or intermediate AMD and 72 control individuals, and metabolites predictive for AMD were identified by a sparse partial least squares discriminant analysis. In our cohort, we identified four metabolite variables that were most predictive for early and intermediate stages of AMD. Increased glutamine and phosphatidylcholine diacyl C28:1 levels were detected in non-advanced AMD cases compared to controls, while the rate of glutaminolysis and the glutamine to glutamate ratio were reduced in non-advanced AMD. The association of glutamine with non-advanced AMD corroborates a recent report demonstrating an elevated glutamine level in early AMD using a different metabolomics technique. In conclusion, this study indicates that metabolomics is a suitable method for the discovery of biomarker candidates for AMD. In the future, larger metabolomics studies could add to the discovery of novel biomarkers in yet unknown AMD pathways and expand our insights in AMD pathophysiology.

Exome sequencing in patients with chronic central serous chorioretinopathy

Chronic central serous chorioretinopathy (cCSC) is a multifactorial eye disease characterized by subretinal fluid accumulation that leads to vision loss. Clinically, cCSC is associated with stress, hypercortisolism and corticosteroid use, and is more frequent in males (80%) than in females (20%). Current genetic studies on cCSC have thus far focussed on common variants, but familial occurrence of cCSC also suggests a role for rare variants in the disease susceptibility. Therefore, in this study, we performed exome sequencing of cCSC patients to elucidate the role of rare (protein-altering) variants in the disease. Exome sequencing was performed on 269 cCSC patients and 1,586 controls. Data were processed according to the Genome-Analysis-Toolkit (GATK) best practices. Principal component analysis was performed to check for genetic ancestry and only unrelated subjects of European descent were retained. Burden, SKAT and SKAT-O tests were performed using 2 different grouping criteria. One group included protein-altering variants only, while the other contained synonymous and splice site variants as well. The gene-based analyses were performed using the SKAT R-package correcting for two principal components using two approaches; (1) on the entire cohort correcting for sex and (2) on males and females separately. Additionally, the gene-based associations of genes at previously reported cCSC loci were investigated. After filtering, the dataset contained 263 cCSC patients (208 males [79%]) and 1352 controls (671 males [50%]) carrying 197,915 protein-altering variants in 16,370 genes and 330,689 exonic variants in 18,173 genes. Analysis stratified by sex identified significant associations with the PIGZ (PSKAT = 9.19 × 10-7 & PSKAT-O = 2.48 × 10-6), DUOX1 (PSKAT = 1.03 × 10-6), RSAD1 (PSKAT = 1.92 × 10-7 & PSKAT-O = 8.57 × 10-8) and LAMB3 (PBurden = 1.40 × 10-6 & PSKAT-O = 1.14 × 10-6) genes in female cCSC patients, after correction for multiple testing. The number of rare variant carriers in these genes was significantly higher in the female cCSC cohort compared to female controls (45,5% vs. 18.5%, P = 1.92 × 10-6, OR = 3.67 [95% CI = 2.09-6.46]). No significant associations were identified in the entire cohort nor in the male patients. In this exome study on cCSC patients, we have identified PIGZ, DUOX1, RSAD1 and LAMB3 as potential new candidate genes for cCSC in females. The sex-specific associations identified here suggest a possible interaction between rare genetic factors and sex for cCSC, but replication of these findings in additional cohorts of cCSC patients is necessary.

Validation of a model for the prediction of retinopathy in persons with type 1 diabetes

BACKGROUND/AIM

To validate a previously developed model for prediction of diabetic retinopathy (DR) for personalised retinopathy screening in persons with type 1 diabetes.

METHODS

Retrospective medical data of persons with type 1 diabetes treated in an academic hospital setting were used for analysis. Sight-threatening retinopathy (STR) was defined as the presence of severe non-proliferative DR, proliferative DR or macular oedema. The presence and grade of retinopathy, onset of diabetes, systolic blood pressure, and levels of haemoglobin A_1c were used to calculate an individual risk estimate and personalised screening interval. In persons with STR, the occurrence was compared with the calculated date of screening. The model's predictive performance was measured using calibration and discrimination techniques.

RESULTS

Of the 268 persons included in our study, 24 (9.0%) developed STR during a mean follow-up of 4.6 years. All incidences of STR occurred after the calculated screening date. By applying the model, the mean calculated screening interval was 30.5 months, which is a reduction in screening frequency of 61% compared with annual screening and 21% compared with biennial screening. The discriminatory ability was good (Harrell's C-statistic=0.82, 95% CI 0.74 to 0.90), and calibration showed an overestimation of risk in persons who were assigned to a higher risk for STR.

CONCLUSION

This validation study suggests that a screening programme based on the previously developed prediction model is safe and efficient. The use of a personalised screening frequency could improve cost-effectiveness of diabetic eye care.

Exome sequencing in families with chronic central serous chorioretinopathy

BACKGROUND

Central serous chorioretinopathy (CSC) is a chorioretinal disease characterized by fluid accumulation between the neuroretina and retinal pigment epithelium with unknown etiology. Family studies have suggested a heritable component for CSC with an autosomal dominant inheritance pattern. Therefore, exome sequencing was performed on familial cCSC to indentify the genetic components contributing to familial cCSC.

METHODS

Exome sequencing was performed on 72 individuals of 18 families with CSC. In these families, we determined whether rare genetic variants (minor allele frequency < 1%) were segregated with CSC and also performed familial gene-burden analysis.

RESULTS

In total, 11 variants segregated in two out of 18 families. One of these variants, c.4145C>T; p.T1382I (rs61758735) in the PTPRB gene, was also associated with CSC in a large case-control cohort sequenced previously (p = 0.009). Additionally, in 28 genes two or more different heterozygous variants segregated in two or more families, but no gene showed consistent associations in both the family gene-burden results and gene-burden analysis in the case-control cohort.

CONCLUSION

We identified potential candidate genes for familial CSC and managed to exclude Mendelian inheritance of variants in one or a limited number of genes. Instead, familial CSC may be a heterogeneous Mendelian disease caused by variants in many different genes, or alternatively CSC may represent a complex disease to which both environmental factors and genetics contribute.

Whole-genome methylation profiling of the retinal pigment epithelium of individuals with age-related macular degeneration reveals differential methylation of the SKI, GTF2H4, and TNXB genes

Background

Age-related macular degeneration (AMD) is a degenerative disorder of the central retina and the foremost cause of blindness. The retinal pigment epithelium (RPE) is a primary site of disease pathogenesis. The genetic basis of AMD is relatively well understood; however, this knowledge is yet to yield a treatment for the most prevalent non-neovascular disease forms. Therefore, tissue-specific epigenetic mechanisms of gene regulation are of considerable interest in AMD. We aimed to identify differentially methylated genes associated with AMD in the RPE and differentiate local DNA methylation aberrations from global DNA methylation changes, as local DNA methylation changes may be more amenable to therapeutic manipulation.

Methods

Epigenome-wide association study and targeted gene expression profiling were carried out in RPE cells from eyes of human donors. We performed genome-wide DNA methylation profiling (Illumina 450k BeadChip array) on RPE cells from 44 human donor eyes (25 AMD and 19 normal controls). We validated the findings using bisulfite pyrosequencing in 55 RPE samples (30 AMD and 25 normal controls) including technical (n = 38) and independent replicate samples (n = 17). Long interspersed nucleotide element 1 (LINE-1) analysis was then applied to assess global DNA methylation changes in the RPE. RT-qPCR on independent donor RPE samples was performed to assess gene expression changes.

Results

Genome-wide DNA methylation profiling identified differential methylation of multiple loci including the SKI proto-oncogene (SKI) (p = 1.18 × 10⁻⁹), general transcription factor IIH subunit H4 (GTF2H4) (p = 7.03 × 10⁻⁷), and Tenascin X (TNXB) (p = 6.30 × 10⁻⁶) genes in AMD. Bisulfite pyrosequencing validated the differentially methylated locus cg18934822 in SKI, and cg22508626 within GTF2H4, and excluded global DNA methylation changes in the RPE in AMD. We further demonstrated the differential expression of SKI, GTF2H4, and TNXB in the RPE of independent AMD donors.

Conclusions

We report the largest genome-wide methylation analysis of RPE in AMD along with associated gene expression changes to date, for the first-time reaching genome-wide significance, and identified novel targets for functional and future therapeutic intervention studies. The novel differentially methylated genes SKI and GTF2H4 have not been previously associated with AMD, and regulate disease pathways implicated in AMD, including TGF beta signaling (SKI) and transcription-dependent DNA repair mechanisms (GTF2H4).

Electronic supplementary material

The online version of this article (10.1186/s13148-019-0608-2) contains supplementary material, which is available to authorized users.

Hyperreflective foci on optical coherence tomography associate with treatment outcome for anti-VEGF in patients with diabetic macular edema

Purpose

To investigate the relationship between baseline number of hyperreflective foci (HF) on spectral domain optical coherence tomography (SD-OCT) in patients with diabetic macular edema (DME), as well as the dynamics of HF during treatment with anti-vascular endothelial growth factor (VEGF), and treatment response.

Methods

We evaluated patients diagnosed with DME scheduled for treatment with intravitreal bevacizumab. Eyes were classified as adequate or insufficient treatment responders based on logMAR visual acuity improvement and central retinal thickness (CRT) decrease after three consecutive injections. Associations between number of HF at baseline and treatment response, the change in HF over the course of treatment, and the distribution of HF within the retinal layers were evaluated.

Results

In 54 eyes of 41 patients, mean number of HF and CRT decreased after intravitreal treatment with bevacizumab (p = 0.002 and p<0.001 respectively). Decrease in CRT after 3 months was independently associated with a higher number of HF at baseline (estimated effect -2.61, 95% CI [-4.42–-0.31], p = 0.006). Eyes with adequate treatment response presented with more HF at baseline (OR 1.106, 95% CI [1.012–1.210], p = 0.030) than eyes with insufficient treatment response. Most HF were located within the inner retinal layers, and decrease of HF was mostly due to a decrease of inner retinal HF.

Conclusions

In patients with DME treated with anti-VEGF, higher baseline numbers of HF have predictive value for treatment response in terms of visual acuity improvement and CRT decrease after 3 months. In addition, HF were responsive to anti-VEGF therapy.

Clinical spectrum of severe chronic central serous chorioretinopathy and outcome of photodynamic therapy

Purpose

To describe a spectrum of severe chronic central serous chorioretinopathy (cCSC) cases and their response to photodynamic therapy (PDT).

Patients and methods

A total of 66 patients (81 eyes) with active severe cCSC were studied, and their response to PDT was compared with a control group consisting of 35 active cCSCs (37 eyes) that did not display characteristics of severity. Best-corrected visual acuity (BCVA) and complete resolution of subretinal fluid (SRF) were considered as main outcome measures.

Results

In severe cCSC cases, we found cumulative areas of diffuse atrophic retinal pigment epithelium alterations in 48 eyes (59%), multiple “hot spots” of leakage in 36 eyes (44%), posterior cystoid retinal degeneration in 25 eyes (31%), and 13 eyes (16%) had a diffuse leakage on fluorescein angiography. After PDT treatment, BCVA increased in both groups, from 66 to 72 Early Treatment of Diabetic Retinopathy Study (ETDRS) letters in the case group (P<0.001), and from 78 to 82 ETDRS letters in the control group (P<0.001). SRF had resolved completely in 87% of severe cCSC cases and 95% of controls at final follow-up visit.

Conclusion

A spectrum of severe cCSC exists, and PDT seems to be an effective treatment in both severe cCSC and nonsevere cCSC in terms of resolution of SRF. Final BCVA shows a significant improvement in both groups after PDT treatment.

Genetic screening for macular dystrophies in patients clinically diagnosed with dry age-related macular degeneration

It can be clinically challenging to distinguish dry age‐related macular degeneration (AMD) from AMD‐mimicking dystrophies, and sometimes misdiagnosis occurs. With upcoming therapies for dry AMD it is important to exclude patients with a different retinal disease from clinical trials. In this study we evaluated the occurrence of AMD‐mimicking dystrophies in an AMD cohort. Whole‐exome sequencing (WES) was performed in 218 patients with intermediate AMD or geographic atrophy secondary to AMD and 133 control individuals. WES data was analyzed for rare variants in 19 genes associated with autosomal dominant and recessive macular dystrophies mimicking AMD. In three (1.4%) of 218 cases we identified a pathogenic heterozygous variant (PRPH2 c.424C > T; p.R142W) causal for autosomal dominant central areolar choroidal dystrophy (CACD). Phenotypically, these patients all presented with geographic atrophy. In 12 (5.5%) of 218 cases we identified a heterozygous variant of unknown clinical significance, but predicted to be highly deleterious, in genes previously associated with autosomal dominant macular dystrophies. The distinction between AMD and AMD‐mimicking dystrophies, such as CACD, can be challenging based on fundus examination alone. Genetic screening for genes associated with macular dystrophies, especially PRPH2, can be beneficial to help identify AMD‐mimicking dystrophies.

Correlation between redefined optical coherence tomography parameters and best-corrected visual acuity in non-resolving central serous chorioretinopathy treated with half-dose photodynamic therapy

Purpose

To assess parameters on optical coherence tomography (OCT), and their correlation with best-corrected visual acuity (BCVA) in patients with non-resolving central serous chorioretinopathy (CSC).

Methods

For 25 non-resolving CSC patients treated with photodynamic therapy (PDT), the thickness of retinal layers was assessed on the foveal spectral-domain (SD) OCT scan. Evaluated OCT parameters included the central retinal thickness (CRT), defined as the internal limiting membrane (ILM) to ellipsoid zone (EZ) distance, and the second band thickness (SBT), defined as the EZ to hyperreflective subretinal accumulation distance. Integrity of the external limiting membrane (ELM) and the EZ bands was also determined. These parameters, along with BCVA and CRT measured automatically by SD-OCT device software were obtained before PDT, after PDT, and at final visit. After Bonferroni correction, a p-value <0.007 was considered statistically significant.

Results

Twenty-five patients could be included at last visit before PDT and first visit after PDT. At final visit, 24 patients could be included, since 1 patients was lost to follow-up. Mean CRT was 112 μm at last visit before PDT, 118 μm at first visit after PDT (p = 0.030), and 127 μm at final visit (p<0.001compared to baseline). Mean SBT was 74 μm, 26 μm (p<0.001 compared to baseline), and 21 μm (p<0.001 compared to baseline), respectively. Mean BCVA in Early Treatment of Diabetic Retinopathy Study letters was 79 at baseline, 85 at first visit after PDT (p = 0.005 compared to baseline), and 87 at final visit (p = 0.001 compared to baseline). BCVA had an estimated correlation of β = 0.103 (p = 0.114) with CRT, β = -0.051 (p = 0.014) with SBT, β = 0.615 (p = 0.600) with the integrity of the ELM, and β = 4.917 with the integrity of the EZ (p = 0.001).

Conclusions

In non-resolving CSC patients treated with half-dose PDT, the CRT increased at final visit in comparison to the last visit before PDT. The continuity of the EZ on SD-OCT was positively correlated with BCVA. We propose that the distance between ILM and EZ should be used as a reliable CRT measurement in non-resolving CSC patients treated with half-dose PDT.

Association of Genetic Variants With Response to Anti-Vascular Endothelial Growth Factor Therapy in Age-Related Macular Degeneration

Importance

Visual acuity (VA) outcomes differ considerably among patients with neovascular age-related macular degeneration (nAMD) treated with anti-vascular endothelial growth factor (VEGF) drugs. Identification of pharmacogenetic associations may help clinicians understand the mechanisms underlying this variability as well as pave the way for personalized treatment in nAMD.

Objective

To identify genetic factors associated with variability in the response to anti-VEGF therapy for patients with nAMD.

Design, Setting, and Participants

In this multicenter genome-wide association study, 678 patients with nAMD with genome-wide genotyping data were included in the discovery phase; 1380 additional patients with nAMD were genotyped for selected common variants in the replication phase. All participants received 3 monthly injections of bevacizumab or ranibizumab. Clinical data were evaluated for inclusion/exclusion criteria from October 2014 to October 2015, followed by data analysis from October 2015 to February 2016. For replication cohort genotyping, clinical data collection and analysis (including meta-analysis) was performed from March 2016 to April 2017.

Main Outcomes and Measures

Change in VA after the loading dose of 3 monthly anti-VEGF injections compared with baseline.

Results

Of the 2058 included patients, 1210 (58.8%) were women, and the mean (SD) age across all cohorts was 78 (7.4) years. Patients included in the discovery cohort and most of the patients in the replication cohorts were of European descent. The mean (SD) baseline VA was 51.3 (20.3) Early Treatment Diabetic Retinopathy Study (ETDRS) score letters, and the mean (SD) change in VA after the loading dose of 3 monthly injections was a gain of 5.1 (13.9) ETDRS score letters (ie, 1-line gain). Genome-wide single-variant analyses of common variants revealed 5 independent loci that reached a P value less than 10 × 10-5. After replication and meta-analysis of the lead variants, rs12138564 located in the CCT3 gene remained nominally associated with a better treatment outcome (ETDRS letter gain, 1.7; β, 0.034; SE, 0.008; P = 1.38 × 10-5). Genome-wide gene-based optimal unified sequence kernel association test of rare variants showed genome-wide significant associations for the C10orf88 (P = 4.22 × 10-7) and UNC93B1 (P = 6.09 × 10-7) genes, in both cases leading to a worse treatment outcome. Patients carrying rare variants in the C10orf88 and UNC93B1 genes lost a mean (SD) VA of 30.6 (17.4) ETDRS score letters (ie, loss of 6.09 lines) and 26.5 (13.8) ETDRS score letters (ie, loss of 5.29 lines), respectively, after 3 months of anti-VEGF treatment.

Conclusions and Relevance

We propose that there is a limited contribution of common genetic variants to variability in nAMD treatment response. Our results suggest that rare protein-altering variants in the C10orf88 and UNC93B1 genes are associated with a worse response to anti-VEGF therapy in patients with nAMD, but these results require further validation in other cohorts.

Risk factors for development and progression of diabetic retinopathy in Dutch patients with type 1 diabetes mellitus

Purpose

To investigate risk factors for the development and progression of diabetic retinopathy (DR) and long‐term visual outcomes in Dutch patients with type 1 diabetes mellitus (T1DM).

Methods

Cumulative incidences were calculated for DR, vision‐threatening DR (VTDR), defined as (pre)proliferative DR and diabetic macular oedema, and best‐corrected visual acuity (BCVA) <0.5 and <0.3 at the most recent eye examination. The following factors were assessed: duration of diabetes, age of onset of T1DM, gender, mean HbA1c, HbA1c variability (defined as coefficient of variation of five separate HbA1c measurements), mean arterial blood pressure, body mass index, albuminuria and lipid profile. We used multivariable Cox regression models to identify factors associated with DR development and progression to VTDR.

Results

We found 25‐year cumulative incidences of 63% for DR, 21% for VTDR, 2% for BCVA <0.5, and 1% for BCVA <0.3. Mean HbA1c (HR 1.023, p < 0.001), HbA1c variability (HR 1.054, p < 0.001), age of onset of T1DM (HR 1.024, p < 0.001), HDL cholesterol (HR 0.502, p = 0.002) and total cholesterol (HR 1.210, p = 0.029) showed an independent association with faster development of any form of DR. The mean HbA1c (HR 1.023, p < 0.001) and the presence of albuminuria (HR 2.940, p = 0.028) were associated with faster progression to VTDR.

Conclusion

These data show relatively low cumulative incidences of DR, VTDR and visual impairment. Higher mean HbA1c, HbA1c variability, age of onset of T1DM and total cholesterol were independently associated with the risk of DR development, and a protective association was found for HDL cholesterol in subjects with T1DM. Mean HbA1c and presence of albuminuria were associated with progression of DR.

Morphological and topographical appearance of microaneurysms on optical coherence tomography angiography

AIMS

To investigate retinal microaneurysms in patients with diabetic macular oedema (DME) by optical coherence tomography angiography (OCTA) according to their location and morphology in relationship to their clinical properties, leakage on fundus fluorescein angiography (FFA) and retinal thickening on structural OCT.

METHODS

OCTA and FFA images of 31 eyes of 24 subjects were graded for the presence of microaneurysms. The topographical and morphological appearance of microaneurysms on OCTA was evaluated and classified. For each microaneurysm, the presence of focal leakage on FFA and associated retinal thickening on OCT was determined.

RESULTS

Of all microaneurysms flagged on FFA, 295 out of 513 (58%) were also visible on OCTA. Microaneurysms with focal leakage and located in a thickened retinal area were more likely to be detected on OCTA than not leaking microaneurysms in non-thickened retinal areas (p=0.001). Most microaneurysms on OCTA were seen in the intermediate (23%) and deep capillary plexus (22%). Of all microaneurysms visualised on OCTA, saccular microaneurysms were detected most often (31%), as opposed to pedunculated microaneurysms (9%). Irregular, fusiform and mixed fusiform/saccular-shaped microaneurysms had the highest likeliness to leak and to be located in thickened retinal areas (p<0.001, p<0.001 and p=0.001).

CONCLUSIONS

Retinal microaneurysms in DME could be classified topographically and morphologically by OCTA. OCTA detected less microaneurysms than FFA, and this appeared to be dependent on leakage activity and retinal thickening. Morphological appearance of microaneurysms (irregular, fusiform and mixed saccular/fusiform) was associated with increased leakage activity and retinal thickening.

Exploring the Use of Molecular Biomarkers for Precision Medicine in Age-Related Macular Degeneration

Precision medicine aims to improve patient care by adjusting medication to each patient's individual needs. Age-related macular degeneration (AMD) is a heterogeneous eye disease in which several pathways are involved, and the risk factors driving the disease differ per patient. As a consequence, precision medicine holds promise for improved management of this disease, which is nowadays a main cause of vision loss in the elderly. In this review, we provide an overview of the studies that have evaluated the use of molecular biomarkers to predict response to treatment in AMD. We predominantly focus on genetic biomarkers, but also include studies that examined circulating or eye fluid biomarkers in treatment response. This involves studies on treatment response to dietary supplements, response to anti-vascular endothelial growth factor, and response to complement inhibitors. In addition, we highlight promising new therapies that have been or are currently being tested in clinical trials and discuss the molecular studies that can help identify the most suitable patients for these upcoming therapeutic approaches.

A new perspective on lipid research in age-related macular degeneration

There is an urgency to find new treatment strategies that could prevent or delay the onset or progression of AMD. Different classes of lipids and lipoproteins metabolism genes have been associated with AMD in a multiple ways, but despite the ever-increasing knowledge base, we still do not understand fully how circulating lipids or local lipid metabolism contribute to AMD. It is essential to clarify whether dietary lipids, systemic or local lipoprotein metabolismtrafficking of lipids in the retina should be targeted in the disease. In this article, we critically evaluate what has been reported in the literature and identify new directions needed to bring about a significant advance in our understanding of the role for lipids in AMD. This may help to develop potential new treatment strategies through targeting the lipid homeostasis.

Whole-Exome Sequencing in Age-Related Macular Degeneration Identifies Rare Variants in COL8A1, a Component of Bruch's Membrane

PURPOSE

Genome-wide association studies and targeted sequencing studies of candidate genes have identified common and rare variants that are associated with age-related macular degeneration (AMD). Whole-exome sequencing (WES) studies allow a more comprehensive analysis of rare coding variants across all genes of the genome and will contribute to a better understanding of the underlying disease mechanisms. To date, the number of WES studies in AMD case-control cohorts remains scarce and sample sizes are limited. To scrutinize the role of rare protein-altering variants in AMD cause, we performed the largest WES study in AMD to date in a large European cohort consisting of 1125 AMD patients and 1361 control participants.

DESIGN

Genome-wide case-control association study of WES data.

PARTICIPANTS

One thousand one hundred twenty-five AMD patients and 1361 control participants.

METHODS

A single variant association test of WES data was performed to detect variants that are associated individually with AMD. The cumulative effect of multiple rare variants with 1 gene was analyzed using a gene-based CMC burden test. Immunohistochemistry was performed to determine the localization of the Col8a1 protein in mouse eyes.

MAIN OUTCOME MEASURES

Genetic variants associated with AMD.

RESULTS

We detected significantly more rare protein-altering variants in the COL8A1 gene in patients (22/2250 alleles [1.0%]) than in control participants (11/2722 alleles [0.4%]; P = 7.07×10^-5). The association of rare variants in the COL8A1 gene is independent of the common intergenic variant (rs140647181) near the COL8A1 gene previously associated with AMD. We demonstrated that the Col8a1 protein localizes at Bruch's membrane.

CONCLUSIONS

This study supported a role for protein-altering variants in the COL8A1 gene in AMD pathogenesis. We demonstrated the presence of Col8a1 in Bruch's membrane, further supporting the role of COL8A1 variants in AMD pathogenesis. Protein-altering variants in COL8A1 may alter the integrity of Bruch's membrane, contributing to the accumulation of drusen and the development of AMD.

Genome-Wide Association Study Reveals Variants in CFH and CFHR4 Associated with Systemic Complement Activation: Implications in Age-Related Macular Degeneration

PURPOSE

To identify genetic variants associated with complement activation, which may help to select age-related macular degeneration (AMD) patients for complement-inhibiting therapies.

DESIGN

Genome-wide association study (GWAS) followed by replication and meta-analysis.

PARTICIPANTS

AMD patients and controls (n = 2245).

METHODS

A GWAS on serum C3d-to-C3 ratio was performed in 1548 AMD patients and controls. For replication and meta-analysis, 697 additional individuals were genotyped. A model for complement activation including genetic and non-genetic factors was built, and the variance explained was estimated. Haplotype analysis was performed for 8 SNPs across the CFH/CFHR locus. Association with AMD was performed for the variants and haplotypes found to influence complement activation.

MAIN OUTCOME MEASURES

Normalized C3d/C3 ratio as a measure of systemic complement activation.

RESULTS

Complement activation was associated independently with rs3753396 located in CFH (P_discovery = 1.09 × 10^-15; P_meta = 3.66 × 10^-21; β = 0.141; standard error [SE] = 0.015) and rs6685931 located in CFHR4 (P_discovery = 8.18 × 10^-7; P_meta = 6.32 × 10^-8; β = 0.054; SE = 0.010). A model including age, AMD disease status, body mass index, triglycerides, rs3753396, rs6685931, and previously identified SNPs explained 18.7% of the variability in complement activation. Haplotype analysis revealed 3 haplotypes (H1-2 and H6 containing rs6685931 and H3 containing rs3753396) associated with complement activation. Haplotypes H3 and H6 conferred stronger effects on complement activation compared with the single variants (P = 2.53 × 10^-14; β = 0.183; SE = 0.024; and P = 4.28 × 10^-4; β = 0.144; SE = 0.041; respectively). Association analyses with AMD revealed that SNP rs6685931 and haplotype H1-2 containing rs6685931 were associated with a risk for AMD development, whereas SNP rs3753396 and haplotypes H3 and H6 were not.

CONCLUSIONS

The SNP rs3753396 in CFH and SNP rs6685931 in CFHR4 are associated with systemic complement activation levels. The SNP rs6685931 in CFHR4 and its linked haplotype H1-2 also conferred a risk for AMD development, and therefore could be used to identify AMD patients who would benefit most from complement-inhibiting therapies.

Geographic distribution of rare variants associated with age-related macular degeneration

PURPOSE

A recent genome-wide association study by the International Age-related Macular Degeneration Genomics Consortium (IAMDGC) identified seven rare variants that are individually associated with age-related macular degeneration (AMD), the most common cause of vision loss in the elderly. In literature, several of these rare variants have been reported with different frequencies and odds ratios across populations of Europe and North America. Here, we aim to describe the representation of these seven AMD-associated rare variants in different geographic regions based on 24 AMD studies.

METHODS

We explored the occurrence of seven rare variants independently associated with AMD (CFH rs121913059 (p.Arg1210Cys), CFI rs141853578 (p.Gly119Arg), C3 rs147859257 (p.Lys155Gln), and C9 rs34882957 (p.Pro167Ser)) and three non-coding variants in or near the CFH gene (rs148553336, rs35292876, and rs191281603) in 24 AMD case-control studies. We studied the difference in distribution, interaction, and effect size for each of the rare variants based on the minor allele frequency within the different geographic regions.

RESULTS

We demonstrate that two rare AMD-associated variants in the CFH gene (rs121913059 [p.Arg1210Cys] and rs35292876) deviate in frequency among different geographic regions (p=0.004 and p=0.001, respectively). The risk estimates of each of the seven rare variants were comparable across the geographic regions.

CONCLUSIONS

The results emphasize the importance of identifying population-specific rare variants, for example, by performing sequencing studies in case-control studies of various populations, because their identification may have implications for diagnostic screening and personalized treatment.

Complement C3 Associates With Incidence of Diabetes, but No Evidence of a Causal Relationship

PURPOSE

This study explored whether complement factor 3 (C3) in plasma is associated with incidence of diabetes in a population-based cohort. We also identified genetic variants related to C3 and explored whether C3 and diabetes share common genetic determinants.

METHODS

C3 was analyzed in plasma from 4368 nondiabetic subjects, 46 to 68 years old, from the Malmö Diet and Cancer Study. Incidence of diabetes was studied in relationship to C3 levels during 17.7± 4.4 years of follow-up. Genotypes associated with C3 were identified in a genome-wide association study. Diabetes Genetics Replication and Meta-Analysis and the European Genetic Database were used for in silico look-up.

RESULTS

In all, 538 (12.3%) subjects developed diabetes during 18 years of follow-up. High C3 was significantly associated with incidence of diabetes after risk factor adjustments (hazard ratio comparing 4th vs 1st quartile, 1.54 (95% confidence interval, 1.13 to 2.09; P = 0.005). C3 was associated with polymorphisms at the complement factor H locus (P < 10-8). However, no relationship with diabetes was observed for this locus. Another eight loci were associated with C3 with P < 10-5. One of them, the glucose kinase regulatory protein (GCKR) locus, has been previously associated with diabetes. The relationship between C3 levels and the GCKR locus was replicated in the European Genetic Database cohort.

CONCLUSIONS

Plasma concentration of C3 is a risk marker for incidence of diabetes. The results suggest that this association could, in part, be explained by pleiotropic effects related to the GCKR gene.

Phenotype Characteristics of Patients With Age-Related Macular Degeneration Carrying a Rare Variant in the Complement Factor H Gene

Importance

Rare variants in the complement factor H (CFH) gene and their association with age-related macular degeneration (AMD) have been described. However, there is limited literature on the phenotypes accompanying these rare variants. Phenotypical characteristics could help ophthalmologists select patients for additional genetic testing.

Objective

To describe the phenotypical characteristics of patients with AMD carrying a rare variant in the CFH gene.

Design, Setting, and Participants

In this cross-sectional study, we searched the genetic database of the department of ophthalmology at the Radboudumc (tertiary ophthalmologic referral center) and the European Genetic Database for patients with AMD with a rare genetic variant in the CFH gene. Patient recruitment took place from March 30, 2006, to February 18, 2013, and data were analyzed from November 30, 2015, to May 8, 2017. Phenotypical features on fundus photographs of both eyes of patients were graded by 2 independent reading center graders masked for carrier status.

Main Outcomes and Measures

Differences in phenotypical characteristics between rare variant carriers and noncarriers were analyzed using univariable generalized estimated equations logistic regression models accounting for intereye correlation.

Results

Analyses included 100 eyes of 51 patients with AMD carrying a CFH variant (mean [SD] age, 66.7 [12.1] years; 64.7% female) and 204 eyes of 102 age-matched noncarriers (mean [SD] age, 67.1 [11.8] years; 54.9% female). Carrying a rare pathogenic CFH variant was associated with larger drusen area (odds ratio range, 6.98 [95% CI, 2.04-23.89] to 18.50 [95% CI, 2.19-155.99]; P = .002), presence of drusen with crystalline appearance (odds ratio, 3.24; 95% CI, 1.24-8.50; P = .02), and drusen nasal to the optic disc (odds ratio range, 4.03 [95% CI, 1.70-9.56] to 7.42 [95% CI, 0.65-84.84]; P = .003).

Conclusions and Relevance

Identification of rare CFH variant carriers may be important for upcoming complement-inhibiting therapies. Patients with an extensive drusen area, drusen with crystalline appearance, and drusen nasal to the optic disc are more likely to have a rare variant in the CFH gene. However, it is not likely that carriers can be discriminated from noncarriers based solely on phenotypical characteristics from color fundus images. Therefore, ophthalmologists should consider genetic testing in patients with these phenotypic characteristics in combination with other patient characteristics, such as early onset, cuticular drusen on fluorescein angiography, and family history of AMD.

Joint Analysis of Nuclear and Mitochondrial Variants in Age-Related Macular Degeneration Identifies Novel Loci TRPM1 and ABHD2/RLBP1

Purpose

Presently, 52 independent nuclear single nucleotide polymorphisms (nSNPs) have been associated with age-related macular degeneration (AMD) but their effects do not explain all its variance. Genetic interactions between the nuclear and mitochondrial (mt) genome may unearth additional genetic loci previously unassociated with AMD risk.

Methods

Joint effects of nSNPs and selected mtSNPs were analyzed by two degree of freedom (2df) joint tests of association in the International AMD Genomics Consortium (IAMDGC) dataset (17,832 controls and 16,144 advanced AMD cases of European ancestry). Subjects were genotyped on the Illumina HumanCoreExome array. After imputation using MINIMAC and the 1000 Genomes Project Phase I reference panel, pairwise linkage disequilibrium pruning, and quality control, 3.9 million nSNPs were analyzed for interaction with mtSNPs chosen based on association in this dataset or publications: A4917G, T5004C, G12771A, and C16069T.

Results

Novel locus TRPM1 was identified with genome-wide significant joint effects (P < 5.0 × 10⁻⁸) of two intronic TRPM1 nSNPs and AMD-associated nonsynonymous MT-ND2 mtSNP A4917G. Stratified analysis by mt allele identified an association only in 4917A (major allele) carriers (P = 4.4 × 10⁻⁹, odds ratio [OR] = 0.90, 95% confidence interval [CI] = 0.87–0.93). Intronic and intergenic ABHD2/RLBP1 nSNPs demonstrated genome-wide significant joint effects (2df joint test P values from 1.8 × 10⁻⁸ to 4.9 × 10⁻⁸) and nominally statistically significant interaction effects with MT-ND5 synonymous mtSNP G12771A. Although a positive association was detected in both strata, the association was stronger in 12771A subjects (P = 0.0020, OR = 2.17, 95% CI = 1.34–3.60).

Conclusions

These results show that joint tests of main effects and gene–gene interaction reveal associations at some novel loci that were missed when considering main effects alone.

Association of a Haplotype in the NR3C2 Gene, Encoding the Mineralocorticoid Receptor, With Chronic Central Serous Chorioretinopathy

Importance

Chronic central serous chorioretinopathy (cCSC) is a chorioretinal disease with unknown disease etiology. The glucocorticoid receptor and the mineralocorticoid receptor, 2 glucocorticoid-binding receptors, might be involved in the pathogenesis of cCSC.

Objective

To assess the association of functional variants and haplotypes in the glucocorticoid receptor (NR3C1) and mineralocorticoid receptor (NR3C2) genes with cCSC.

Design, Setting, and Participants

In this case-control genetic association study, 336 patients with cCSC and 1314 unaffected controls, collected at 3 university medical centers from September 1, 2009, to May 1, 2016, underwent KASP genotyping for selected variants in NR3C1 (rs56149945, rs41423247, and rs6198) and NR3C2 (rs2070951 and rs5522).

Main Outcomes and Measures

Genetic associations of 3 NR3C1 variants and 2 NR3C2 variants with cCSC.

Results

Among the 336 patients (274 men and 62 women; mean [SD] age, 52 [10] years), after correction for multiple testing, rs2070951 in the NR3C2 gene was significantly associated with cCSC (odds ratio, 1.29; 95% CI, 1.08-1.53; P = .004). Moreover, the GA haplotype of single-nucleotide polymorphisms rs2070951 and rs5522 in NR3C2 conferred risk for cCSC (odds ratio, 1.39; 95% CI, 1.15-1.68; P = .004), whereas the CA haplotype decreased risk for cCSC (odds ratio, 0.72; 95% CI, 0.60-0.87; P < .001). Three known variants in NR3C1 that alter the activity of the glucocorticoid receptor (rs56149945, rs41423247, and rs6198) were not associated with cCSC.

Conclusions and Relevance

In this study, the variant rs2070951 and the GA haplotype in NR3C2 were associated with an increased risk for cCSC. Results of this genetic study support a possible role for the mineralocorticoid receptor in the pathogenesis of cCSC. Since these haplotypes have previously been associated with perceived stress, this study provides a clue to bridging clinical risk factors for cCSC to underlying genetic associations.

Omics Biomarkers in Ophthalmology

"Omics" refers to high-throughput analyses of genes, proteins, or metabolites in a biological system, and is increasingly used for ophthalmic research. These system-based approaches can unravel disease-related processes and are valuable for biomarker discovery. Furthermore, potential therapeutic targets can be identified based on omics results, and targeted follow-up experiments can be designed to gain molecular understanding of the disease and to test new therapies. Here, we review the application of omics techniques in eye diseases, focusing on age-related macular degeneration (AMD), diabetic retinopathy (DR), retinal detachment (RD), myopia, glaucoma, Fuchs' corneal dystrophy (FCD), cataract, keratoconus, and dry eyes. We observe that genomic analyses were mainly successful in AMD research (almost half of the genomic heritability has been explained), whereas large parts of disease variability or risk remain unsolved in most of the other diseases. Other omics studies like transcriptomics, proteomics, and metabolomics provided additional candidate proteins and pathways for several eye diseases, although sample sizes in these studies were often very small and replication is lacking. In order to translate omics results into clinical biomarkers, larger sample sizes and validation across different cohorts would be essential. In conclusion, omics-based studies are increasing in ophthalmology, and further application to the clinic might develop in the years to come. Integration of genomics with other type of omics data has the potential to improve the accuracy of predictive tests. Moreover, in the future, omics may lead to stratification of patients into subgroups based on molecular profiles, enabling the development of personalized treatments.

The Functional Effect of Rare Variants in Complement Genes on C3b Degradation in Patients With Age-Related Macular Degeneration

Importance

In age-related macular degeneration (AMD), rare variants in the complement system have been described, but their functional consequences remain largely unexplored.

Objectives

To identify new rare variants in complement genes and determine the functional effect of identified variants on complement levels and complement regulation in serum samples from carriers and noncarriers.

Design, Setting, and Participants

This study evaluated affected (n = 114) and unaffected (n = 60) members of 22 families with AMD and a case-control cohort consisting of 1831 unrelated patients with AMD and 1367 control individuals from the European Genetic Database from March 29, 2006, to April 26, 2013, in Nijmegen, the Netherlands, and Cologne, Germany. Exome sequencing data of families were filtered for rare variants in the complement factor H (CFH), complement factor I (CFI), complement C9 (C9), and complement C3 (C3) genes. The case-control cohort was genotyped with allele-specific assays. Serum samples were obtained from carriers of identified variants (n = 177) and age-matched noncarriers (n = 157). Serum concentrations of factor H (FH), factor I (FI), C9, and C3 were measured, and C3b degradation ability was determined.

Main Outcomes and Measures

Association of rare variants in the CFH, CFI, C9, and C3 genes with AMD, serum levels of corresponding proteins, and C3b degradation ability of CFH and CFI variant carriers.

Results

The 1831 unrelated patients with AMD had a mean (SD) age of 75.0 (9.4) years, and 60.5% were female. The 1367 unrelated control participants had a mean (SD) age of 70.4 (7.0), and 58.7% were female. All individuals were of European descent. Rare variants in CFH, CFI, C9, and C3 contributed to an increased risk of developing AMD (odds ratio, 2.04; 95% CI, 1.47-2.82; P < .001). CFI carriers had decreased median FI serum levels (18.2 μg/mL in Gly119Arg carriers and 16.2 μg/mL in Leu131Arg carriers vs 27.2 and 30.4 μg/mL in noncarrier cases and controls, respectively; both P < .001). Elevated C9 levels were observed in Pro167Ser carriers (10.7 µg/mL vs 6.6 and 6.1 µg/mL in noncarrier cases and controls, respectively; P < .001). The median FH serum levels were 299.4 µg/mL for CFH Arg175Gln and 266.3 µg/mL for CFH Ser193Leu carriers vs 302.4 and 283.0 µg/mL for noncarrier cases and controls, respectively. The median C3 serum levels were 943.2 µg/mL for C3 Arg161Trp and 946.7 µg/mL for C3 Lys155Gln carriers vs 874.0 and 946.7 µg/mL for noncarrier cases and controls, respectively. The FH and FI levels correlated with C3b degradation in noncarriers (R2 = 0.35 and R2 = 0.31, respectively; both P < .001).

Conclusions and Relevance

Reduced serum levels were associated with C3b degradation in carriers of CFI but not CFH variants, suggesting that CFH variants affect functional activity of FH rather than serum levels. Carriers of CFH (Arg175Gln and Ser193Leu) and CFI (Gly119Arg and Leu131Arg) variants have an impaired ability to regulate complement activation and may benefit more from complement-inhibiting therapy than patients with AMD in general.

Systemic and ocular fluid compounds as potential biomarkers in age-related macular degeneration

Biomarkers can help unravel mechanisms of disease and identify new targets for therapy. They can also be useful in clinical practice for monitoring disease progression, evaluation of treatment efficacy, and risk assessment in multifactorial diseases, such as age-related macular degeneration (AMD). AMD is a highly prevalent progressive retinal disorder for which multiple genetic and environmental risk factors have been described, but the exact etiology is not yet fully understood. Many compounds have been evaluated for their association with AMD. We performed an extensive literature review of all compounds measured in serum, plasma, vitreous, aqueous humor, and urine of AMD patients. Over 3600 articles were screened, resulting in more than 100 different compounds analyzed in AMD studies, involved in neovascularization, immunity, lipid metabolism, extracellular matrix, oxidative stress, diet, hormones, and comorbidities (such as kidney disease). For each compound, we provide a short description of its function and discuss the results of the studies in relation to its usefulness as AMD biomarker. In addition, biomarkers identified by hypothesis-free techniques, including metabolomics, proteomics, and epigenomics, are covered. In summary, compounds belonging to the oxidative stress pathway, the complement system, and lipid metabolism are the most promising biomarker candidates for AMD. We hope that this comprehensive survey of the literature on systemic and ocular fluid compounds as potential biomarkers in AMD will provide a stepping stone for future research and possible implementation in clinical practice.

Neovascular age-related macular degeneration without drusen in the fellow eye: clinical spectrum and therapeutic outcome

Purpose

To investigate the clinical characteristics and therapeutic outcome of patients with neovascular age-related macular degeneration (nAMD) in 1 eye, without drusen in the fellow eye.

Patients and methods

Medical records of 381 patients were analyzed to identify the cases. The main outcomes included Early Treatment Diabetic Retinopathy Study (ETDRS) best-corrected visual acuity (BCVA) and change in central retinal thickness (CRT). These parameters were reviewed at baseline, first follow-up visit, and after 6, 12, and 24 months.

Results

Out of 381 patients, 29 cases (8%) were included (of whom 3 had polypoidal choroidal vasculopathy [PCV]) who were treated with anti-vascular endothelial growth factor (anti-VEGF) therapy which was supplemented by photodynamic therapy (PDT) in the PCV patients. Overall, no statistically significant change in mean BCVA was observed during follow-up. BCVA improved or remained stable (defined as a gain in BCVA, a stable BCVA, or a loss of <5 ETDRS letters) in 22 patients (76%), and 7 patients (23%) had lost ≥5 ETDRS letters at final follow-up. A gain of ≥15 ETDRS letters at final follow-up was seen in 5 patients (17%). Mean CRT had decreased significantly with 99 µm (P<0.001) at 24 months after the initial visit.

Conclusion

There is a clinical spectrum of nAMD that is not associated with drusen in the fellow eye. Patients with nAMD without drusen in the fellow eye respond to anti-VEGF treatment and, in cases of PCV, to supplemental PDT. The pathophysiology of this spectrum of nAMD may be different from drusen-associated age-related macular degeneration.

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

•

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

•

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

•

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

•

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

•

Functional assays can help identify patients for complement inhibiting therapies.

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

GWAS study using DNA pooling strategy identifies association of variant rs4910623 in OR52B4 gene with anti-VEGF treatment response in age-related macular degeneration

Pooled DNA based GWAS to determine genetic association of SNPs with visual acuity (VA) outcome in anti-vascular endothelial growth factor (anti-VEGF) treated neovascular age-related macular degeneration (nAMD) patients. We performed pooled DNA based GWAS on 285 anti-VEGF treated nAMD patients using high density Illumina 4.3 M array. Primary outcome was change in VA in Early Treatment Diabetic Retinopathy Study (ETDRS) letters after 6 months of anti-VEGF treatment (patients who lost ≥5 ETDRS letters classified as non-responders and all remaining classified as responders). GWAS analysis identified 44 SNPs of interest: 37 with strong evidence of association (p < 9 × 10⁻⁸), 2 in drug resistance genes (p < 5 × 10⁻⁶) and 5 nonsynonymous changes (p < 1 × 10⁻⁴). In the validation phase, individual genotyping of 44 variants showed three SNPs (rs4910623 p = 5.6 × 10⁻⁵, rs323085 p = 6.5 × 10⁻⁴ and rs10198937 p = 1.30 × 10⁻³) remained associated with VA response at 6 months. SNP rs4910623 also associated with treatment response at 3 months (p = 1.5 × 10⁻³). Replication of these three SNPs in 376 patients revealed association of rs4910623 with poor VA response after 3 and 6 months of treatment (p = 2.4 × 10⁻³ and p = 3.5 × 10⁻², respectively). Meta-analysis of both cohorts (673 samples) confirmed association of rs4910623 with poor VA response after 3 months (p = 1.2 × 10⁻⁵) and 6 months (p = 9.3 × 10⁻⁶) of treatment in nAMD patients.

Efficacy of photodynamic therapy in steroid-associated chronic central serous chorioretinopathy: a case-control study

PURPOSE

To investigate whether patients who developed chronic central serous chorioretinopathy (cCSC) in association with corticosteroid treatment respond differently to photodynamic therapy (PDT) as compared to patients who have not used corticosteroids.

METHODS

Clinical evaluation included visual acuity (VA), fundoscopy, optical coherence tomography (OCT), fluorescein and indocyanine green angiography. The main outcome measure was a complete resolution of subretinal fluid (SRF) on OCT after PDT.

RESULTS

One hundred and twenty-three eyes (117 patients), including 35 steroid-associated cases (29%), who received PDT treatment with reduced settings for active cCSC were included. Complete resolution of SRF on OCT was seen in 69% of the steroid-associated cases and in 50% of the controls after PDT treatment (p = 0.062). At the final follow-up moment, 74% of the cases had a complete resolution of SRF compared to 60% in the control group (p = 0.142). The VA at the first visit after therapy showed an increase in both groups (mean VA before treatment; cases: 69 ± 14 Early Treatment Diabetic Retinopathy Study (ETDRS) letters, controls: 74 ± 13 ETDRS letters, mean VA first visit after treatment; cases: 76 ± 13 ETDRS letters, controls: 75 ± 13 ETDRS letters). No significant differences were seen in response to PDT between the patients who continued corticosteroid treatment and those who ceased the use of corticosteroids.

CONCLUSIONS

Photodynamic therapy appears to be equally effective in patients suffering from steroid-associated cCSC as compared to patients with cCSC who do not use corticosteroids. Continuation of corticosteroids at the time of PDT treatment does not seem to adversely affect PDT response.

Rare Genetic Variants Associated With Development of Age-Related Macular Degeneration

IMPORTANCE

Rare variants in the complement genes CFH, CFI, C9, and C3 have been found to be highly associated with age-related macular degeneration (AMD); however, the effect on clinical characteristics and familial segregation by these variants is lacking.

OBJECTIVES

To determine the contribution of rare CFH Arg1210Cys, CFI Gly119Arg, C9 Pro167Ser, and C3 Lys155Gln variants in the development of AMD in 22 multiplex families and to describe clinical differences in carriers vs noncarriers in these families and a large case-control cohort.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective case-control study included 114 affected and 60 unaffected members of 22 multiplex families with AMD as well as 1589 unrelated patients with AMD and 1386 unrelated control individuals enrolled in the European Genetic Database (EUGENDA). Patients were recruited from March 29, 2006, to April 26, 2013, and data were collected from April 20, 2012, to May 7, 2014. All participants underwent an extensive ophthalmic examination and completed a questionnaire. Venous blood samples were obtained from all participants for genetic analysis, including whole-exome sequencing and measurements of complement activation. Data were analyzed from September 23, 2014, to November 4, 2015.

MAIN OUTCOMES AND MEASURES

Differences between carriers and noncarriers of rare variants in age at onset of symptoms, the family history of AMD, complement activation levels (C3d:C3 ratio), the presence of reticular pseudodrusen, and AMD phenotype.

RESULTS

Among the 114 affected and 60 unaffected members of 22 multiplex families with AMD and the 1598 unrelated patients with AMD and 1386 controls in the EUGENDA cohort who underwent analysis, the presence of the CFI Gly119Arg, C9 Pro167Ser, or C3 Lys155Gln variant was confirmed in 18 individuals in 5 families but did not completely segregate with the disease. In the case-control cohort, the 91 affected carriers of these variants were younger at symptom onset (mean [SD] age, 67.4 [8.5] vs 71.3 [8.9] years; P = .01) and more often reported a positive family history (35 of 79 [44.3%] vs 367 of 1201 [30.6%]; P = .008) compared with the 1498 noncarriers. Patients with advanced atrophic AMD carried these rare variants more frequently than patients with neovascular AMD (11 of 93 [11.8%] vs 40 of 835 [4.8%]; P = .04).

CONCLUSIONS AND RELEVANCE

Previously reported rare variants do not completely segregate within families with AMD. However, patients carrying these rare variants differ clinically from noncarriers by an earlier age at symptom onset, higher prevalence of a positive family history, and AMD phenotype. These results suggest that genetic tests for AMD might be designed to detect common and rare genetic variants, especially in families, because rare variants contribute to the age at onset and progression of the disease.

A Novel Complotype Combination Associates with Age-Related Macular Degeneration and High Complement Activation Levels in vivo

The complement system is the first line of defense against foreign intruders, and deregulation of this system has been described in multiple diseases. In age-related macular degeneration (AMD), patients have higher complement activation levels compared to controls. Recently, a combination of three single nucleotide polymorphisms (SNPs) in genes of the complement system, referred to as a complotype, has been described to increase complement activation in vitro. Here we describe a novel complotype composed of CFB (rs4151667)-CFB (rs641153)-CFH (rs800292), which is strongly associated with both AMD disease status (p = 5.84*10⁻¹³) and complement activation levels in vivo (p = 8.31*10⁻⁹). The most frequent genotype combination of this complotype was associated with the highest complement activation levels in both patients and controls. These findings are relevant in the context of complement-lowering treatments for AMD that are currently under development. Patients with a genetic predisposition to higher complement activation levels will potentially benefit the most of such treatments.

Genetic Variants and Systemic Complement Activation Levels Are Associated With Serum Lipoprotein Levels in Age-Related Macular Degeneration

PURPOSE

Genetic variants in genes encoding components of lipid metabolism have been associated with AMD. The aims of this study were to evaluate the relation of these genetic variants with serum lipid levels in AMD in a large case-control cohort (n = 3070) and to test for correlations between lipids and complement activation.

METHODS

Single nucleotide polymorphisms (SNPs) in eight lipid metabolism genes, previously described to be associated with AMD, were genotyped and tested for their association in our case-control cohort. Serum apolipoprotein B (ApoB), apolipoprotein AI (Apo-AI), cholesterol, triglycerides (TG), high-density lipoprotein-cholesterol (HDLC), and complement activation levels (C3d/C3) were measured and tested for association with AMD. Non-HDL cholesterol and LDL were inferred based on the measurements of the other lipids and lipoproteins. General linear models and χ2 tests were used to evaluate the relation of SNPs and lipids/lipoproteins to the disease as well as their interrelations.

RESULTS

Significant genotypic associations with AMD were observed for SNPs in CETP, APOE, and FADS1. The serum levels of Apo-AI and HDLC were significantly higher in patients compared with controls. Triglycerides (TG) levels were lower in AMD compared with controls. A cumulative effect was observed for APOE and CETP genotypes on HDLC and Apo-AI levels. Complement activation levels correlated positively with HDLC and Apo-AI, and negatively with TG. Both the lipids/lipoproteins and the complement activation levels associate independently to AMD.

CONCLUSIONS

This study bridges the gap between genetic associations and physiological lipid levels in AMD. Additionally, the observed correlations between complement activation and lipid levels link two major systems that previously were always assessed independently.

Whole Exome Sequencing in Patients with the Cuticular Drusen Subtype of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in elderly people worldwide. Cuticular drusen (CD) is a clinical subtype of AMD, which typically displays an earlier age at onset, and has a strong genetic component. Genetic studies support a role for rare sequence variants in CD susceptibility, and rare sequence variants in the CFH gene have been identified in 8.8% of CD cases. To further explore the role of rare variants in CD, we performed whole exome sequencing (WES) in 14 affected members of six families and 12 sporadic cases with CD. We detected rare sequence variants in CFH and FBLN5, which previously were shown to harbor rare variants in patients with CD. In addition, we detected heterozygous rare sequence variants in several genes encoding components of the extracellular matrix (ECM), including FBLN1, FBLN3/EFEMP1, FBLN5, FBLN6/HMCN1, FBN2, and COL15A1. Two rare pathogenic variants were identified in the COL15A1 gene: one in a sporadic case and another was found to segregate in a family with six affected individuals with CD. In addition, two rare pathogenic variants were identified in the FGL1 gene in three unrelated CD cases. These findings suggest that alterations in the ECM and in the coagulation pathway may play a role in the pathogenesis of CD. The identified candidate genes require further analyses in larger cohorts to confirm their role in the CD subtype of AMD. No evidence was found of rare sequence variants in a single gene that segregate with CD in the six families, suggesting that the disease is genetically heterogeneous.

Genomic Copy Number Variations of the Complement Component C4B Gene Are Associated With Chronic Central Serous Chorioretinopathy

PURPOSE

Chronic central serous chorioretinopathy (cCSC) has recently been associated to variants in the complement factor H gene. To further investigate the role of the complement system in cCSC, the genomic copy number variations in the complement component 4 gene (C4) were studied.

METHODS

C4A and C4B copy numbers were analyzed in 197 cCSC patients and 303 healthy controls by using a Taqman copy number determination assay. Copy numbers of C4A, C4B, and the total C4 load were compared between cases and controls, by using a Fisher exact test. For this analysis Bonferroni correction was performed for three tests, and P values < 0.017 were considered to be significant. A logistic regression model was constructed to calculate the odds ratios (ORs) of each of the C4B copy numbers, using two copies as a reference. For this model P values < 0.05 were considered to be significant.

RESULTS

C4B genomic copy numbers differed significantly between cCSC patients and healthy controls (P = 0.0018). Absence of C4B significantly conferred risk of cCSC (P = 0.039, OR = 2.61 [95% confidence interval (CI) = 1.05-6.52]), whereas three copies of C4B significantly decreased the risk of cCSC (P = 0.014, OR = 0.45 [95% CI = 0.23-0.85]). The C4A genomic copy numbers and total C4 load did not significantly differ between cases and controls.

CONCLUSIONS

This study showed that copy numbers of C4B are significantly associated with cCSC. Carrying no copies of C4B significantly increases the risk of cCSC, whereas carrying three C4B copies is protective. These findings reinforce the hypothesis of a possible involvement of the complement system in the pathogenesis of cCSC.

Analysis of rare variants in the CFH gene in patients with the cuticular drusen subtype of age-related macular degeneration

PURPOSE

Age-related macular degeneration (AMD) and cuticular drusen (CD), a clinical subtype of AMD, have been linked to genetic variants in the complement factor H (CFH) gene. In this study, we aimed to investigate the frequency of rare variants in the CFH gene in 180 cases with CD. In addition, we aimed to determine the frequency of a previously reported rare, highly penetrant CFH variant (p.Arg1210Cys) in a Dutch-German non-CD-type AMD case-control cohort, and to describe the phenotype of patients carrying the p.Arg1210Cys variant.

METHODS

Study subjects were selected from the European Genetic Database (EUGENDA), a joint AMD database of the Radboud University Medical Centre and the University Hospital of Cologne, and graded at the Cologne Image Reading Centre and Laboratory (CIRCL). Additionally, two CD cases were recruited from the VU Medical Centre in Amsterdam. The CFH gene was analyzed in 180 CD cases with Sanger sequencing. All identified variants were analyzed for potential damaging effects with prediction software tools Sorting Intolerant from Tolerant (SIFT) and Polymorphism Phenotyping (PolyPhen). In addition, we genotyped the p.Arg1210Cys variant in 813 non-CD type AMD cases and 1175 controls.

RESULTS

Sequencing identified 11 rare, heterozygous missense variants, one frameshift variant, and one splice acceptor site variant in 16 CD cases. The p.Arg1210Cys variant was identified in two CD cases but was not identified in our Dutch-German non-CD-type AMD case-control cohort.

CONCLUSIONS

The present study identified the presence of rare variants in the CFH gene in 16 (8.8%) of 180 patients with the CD subtype of AMD. The carriers of rare CFH variants displayed a significantly earlier age at onset than non-carriers (p=0.016). The rare missense variant p.Arg1210Cys was identified in two CD cases, but was not detected in 813 non-CD type AMD cases or in the 1,175 controls of our Dutch-German cohort. The current study suggests that the p.Arg1210Cys variant may be restricted to a subset of patients with the CD subtype of AMD. Detailed clinical phenotyping, including fluorescein angiography, of patients with AMD carrying the p.Arg1210Cys variant in other cohorts is required to confirm this finding.

Highly penetrant alleles in age-related macular degeneration

Age-related macular degeneration (AMD) is a complex disease caused by a combination of genetic and environmental factors. Genome-wide association studies have identified several common genetic variants associated with AMD, which together account for 15%-65% of the heritability of AMD. Multiple hypotheses to clarify the unexplained portion of genetic variance have been proposed, such as gene-gene interactions, gene-environment interactions, structural variations, epigenetics, and rare variants. Several studies support a role for rare variants with large effect sizes in the pathogenesis of AMD. In this work, we review the methods that can be used to detect rare variants in common diseases, as well as the recent progress that has been made in the identification of rare variants in AMD. In addition, the relevance of these rare variants for diagnosis, prognosis, and treatment of AMD is highlighted.