A multi-ethnic genome-wide association study implicates collagen matrix integrity and cell differentiation pathways in keratoconus.

Keratoconus is characterised by reduced rigidity of the cornea with distortion and focal thinning that causes blurred vision, however, the pathogenetic mechanisms are unknown. It can lead to severe visual morbidity in children and young adults and is a common indication for corneal transplantation worldwide. Here we report the first large scale genome-wide association study of keratoconus including 4,669 cases and 116,547 controls. We have identified significant association with 36 genomic loci that, for the first time, implicate both dysregulation of corneal collagen matrix integrity and cell differentiation pathways as primary disease-causing mechanisms. The results also suggest pleiotropy, with some disease mechanisms shared with other corneal diseases, such as Fuchs endothelial corneal dystrophy. The common variants associated with keratoconus explain 12.5% of the genetic variance, which shows potential for the future development of a diagnostic test to detect susceptibility to disease.

Association of Genetic Variation With Keratoconus.

Importance: Keratoconus is a condition in which the cornea progressively thins and protrudes in a conical shape, severely affecting refraction and vision. It is a major indication for corneal transplant. To discover new genetic loci associated with keratoconus and better understand the causative mechanism of this disease, we performed a genome-wide association study on patients with keratoconus. Objective: To identify genetic susceptibility regions for keratoconus in the human genome. Design, Setting, and Participants: This study was conducted with data from eye clinics in Australia, the United States, and Northern Ireland. The discovery cohort of individuals with keratoconus and control participants from Australia was genotyped using the Illumina HumanCoreExome single-nucleotide polymorphism array. After quality control and data cleaning, genotypes were imputed against the 1000 Genomes Project reference panel (phase III; version 5), and association analyses were completed using PLINK version 1.90. Single-nucleotide polymorphisms with P < 1.00 × 10-6 were assessed for replication in 3 additional cohorts. Control participants were drawn from the cohorts of the Blue Mountains Eye Study and a previous study of glaucoma. Replication cohorts were from a previous keratoconus genome-wide association study data set from the United States, a cohort of affected and control participants from Australia and Northern Ireland, and a case-control cohort from Victoria, Australia. Data were collected from January 2006 to March 2019. Main Outcomes and Measures: Associations between keratoconus and 6 252 612 genetic variants were estimated using logistic regression after adjusting for ancestry using the first 3 principal components. Results: The discovery cohort included 522 affected individuals and 655 control participants, while the replication cohorts included 818 affected individuals (222 from the United States, 331 from Australia and Northern Ireland, and 265 from Victoria, Australia) and 3858 control participants (2927 from the United States, 229 from Australia and Northern Ireland, and 702 from Victoria, Australia). Two novel loci reached genome-wide significance (defined as P < 5.00 × 10-8), with a P value of 7.46 × 10-9 at rs61876744 in patatin-like phospholipase domain-containing 2 gene (PNPLA2) on chromosome 11 and a P value of 6.35 × 10-12 at rs138380, 2.2 kb upstream of casein kinase I isoform epsilon gene (CSNK1E) on chromosome 22. One additional locus was identified with a P value less than 1.00 × 10-6 in mastermind-like transcriptional coactivator 2 (MAML2) on chromosome 11 (P = 3.91 × 10-7). The novel locus in PNPLA2 reached genome-wide significance in an analysis of all 4 cohorts (P = 2.45 × 10-8). Conclusions and Relevance: In this relatively large keratoconus genome-wide association study, we identified a genome-wide significant locus for keratoconus in the region of PNPLA2 on chromosome 11.

Do age-related macular degeneration genes show association with keratoconus?

BACKGROUND: Keratoconus (KC) is a common corneal condition with an unknown gender predominance. Although numerous studies have investigated the genetic component of KC, no specific genes have yet been attributed to the condition. We recently reported posterior segment changes occurring in the eyes of KC patients. However, it is not clear whether these changes are part of KC pathogenesis or reflect changes in anatomical features of the eye manifested by changes at the cornea. Given retinal changes represent the main characteristics observed in age-related macular degeneration (AMD) and that pleiotropy has been demonstrated between different eye diseases, we wished to assess if known AMD associated genes were also associated with KC. METHODS: A total of 248 KC subjects and 366 non-KC (control) subjects were recruited from public and private clinics in Melbourne for this analysis. Nineteen single nucleotide polymorphisms (SNPs) previously associated with AMD, including rs10490924 (ARMS2/HTRA1), rs10737680 (CFH), rs13278062 (TNFRSF10A), rs1864163 (CETP), rs2230199 (C3), rs3130783 (IER3/DDR1), rs334353 (TGFBR1), rs3812111 (COL10A1), rs429608 (C2/CFB), rs4420638 (APOE), rs4698775 (CFI), rs5749482 (TIMP3), rs6795735 (ADAMTS9), rs8017304 (RAD51B), rs8135665 (SLC16A8), rs920915 (LIPC), rs943080 (VEGFA), rs9542236 (B3GALTL) and rs13081855 (COL8A1/FILIP1L), were genotyped in this cohort. Logistic regression was applied to evaluate the association between these SNPs and KC on both genders together, as well as each gender separately. Linear regression was also applied to assess the association between SNPs and corneal curvature. Bonferroni correction was applied to adjust for multiple testing. RESULTS: Genotyping data were available for 18 SNPs. The SNP, rs6795735 (ADAMTS9) was significantly associated with KC (p = 3.5 × 10- 4) when both genders were assessed, whereas rs5749482 (TIMP3) was only associated in males (p = 7.7 × 10- 4) following Bonferroni multiple correction. However, when the covariates of age and gender were included, the associations became non-significant. In addition, none of the SNPs appeared significant for corneal curvature. CONCLUSIONS: Our study suggested a potential association of rs6795735 in the ADAMTS9 gene and rs5749482 in the TIMP3 gene in KC and that different associations may be gender specific. Overall, SNPs initially identified as associated with AMD following multiple correction may be further impacted by other factors such as age or gender and further studies are needed to resolve this issue.

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; ß, 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.

Recurrent structural variation, clustered sites of selection, and disease risk for the complement factor H (CFH) gene family.

Structural variation and single-nucleotide variation of the complement factor H (CFH) gene family underlie several complex genetic diseases, including age-related macular degeneration (AMD) and atypical hemolytic uremic syndrome (AHUS). To understand its diversity and evolution, we performed high-quality sequencing of this ∼360-kbp locus in six primate lineages, including multiple human haplotypes. Comparative sequence analyses reveal two distinct periods of gene duplication leading to the emergence of four CFH-related (CFHR) gene paralogs (CFHR2 and CFHR4 ∼25-35 Mya and CFHR1 and CFHR3 ∼7-13 Mya). Remarkably, all evolutionary breakpoints share a common ∼4.8-kbp segment corresponding to an ancestral CFHR gene promoter that has expanded independently throughout primate evolution. This segment is recurrently reused and juxtaposed with a donor duplication containing exons 8 and 9 from ancestral CFH, creating four CFHR fusion genes that include lineage-specific members of the gene family. Combined analysis of >5,000 AMD cases and controls identifies a significant burden of a rare missense mutation that clusters at the N terminus of CFH [P = 5.81 × 10-8, odds ratio (OR) = 9.8 (3.67-Infinity)]. A bipolar clustering pattern of rare nonsynonymous mutations in patients with AMD (P < 10-3) and AHUS (P = 0.0079) maps to functional domains that show evidence of positive selection during primate evolution. Our structural variation analysis in >2,400 individuals reveals five recurrent rearrangement breakpoints that show variable frequency among AMD cases and controls. These data suggest a dynamic and recurrent pattern of mutation critical to the emergence of new CFHR genes but also in the predisposition to complex human genetic disease phenotypes.

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.

Multiallelic copy number variation in the complement component 4A (C4A) gene is associated with late-stage age-related macular degeneration (AMD).

BACKGROUND: Age-related macular degeneration (AMD) is the leading cause of vision loss in Western societies with a strong genetic component. Candidate gene studies as well as genome-wide association studies strongly implicated genetic variations in complement genes to be involved in disease risk. So far, no association of AMD with complement component 4 (C4) was reported probably due to the complex nature of the C4 locus on chromosome 6. METHODS: We used multiplex ligation-dependent probe amplification (MLPA) to determine the copy number of the C4 gene as well as of both relevant isoforms, C4A and C4B, and assessed their association with AMD using logistic regression models. RESULTS: Here, we report on the analysis of 2645 individuals (1536 probands and 1109 unaffected controls), across three different centers, for multiallelic copy number variation (CNV) at the C4 locus. We find strong statistical significance for association of increased copy number of C4A (OR 0.81 (0.73; 0.89);P = 4.4 × 10(-5)), with the effect most pronounced in individuals over 78 years (OR 0.67 (0.55; 0.81)) and females (OR 0.77 (0.68; 0.87)). Furthermore, this association is independent of known AMD-associated risk variants in the nearby CFB/C2 locus, particularly in females and in individuals over 78 years. CONCLUSIONS: Our data strengthen the notion that complement dysregulation plays a crucial role in AMD etiology, an important finding for early intervention strategies and future therapeutics. In addition, for the first time, we provide evidence that multiallelic CNVs are associated with AMD pathology.

Association Study of Mannose-Binding Lectin Levels and Genetic Variants in Lectin Pathway Proteins with Susceptibility to Age-Related Macular Degeneration: A Case-Control Study.

BACKGROUND: In age-related macular degeneration (AMD) the complement system is thought to be activated by chronic oxidative damage with genetic variants identified in the alternative pathway as susceptibility factors. However, the involvement of the lectin pathway of complement, a key mediator of oxidative damage, is controversial. This study investigated whether mannose-binding lectin (MBL) levels and genetic variants in lectin pathway proteins, are associated with the predisposition to and severity of AMD. METHODS: MBL levels and single nucleotide polymorphisms (SNPs) in the MBL2 and the ficolin-2 (FCN2) gene were determined in 109 patients with AMD and 109 age- and sex-matched controls. RESULTS: MBL expression levels were equally distributed in both cases (early and late AMD) and controls (p>0.05). However, there was a trend towards higher median MBL levels in cases with late AMD compared to cases with early AMD (1.0 vs. 0.4 µg/ml, p = 0.09) and MBL deficiency (<0.5 µg/ml) was encountered less frequently in the late AMD group (35% vs 56%, p = 0.03). FCN2 and MBL2 allele frequencies were similarly distributed in early and late AMD cases compared with controls (p>0.05 for all analyses) as were MBL2 genotypes. Similarly, there was no significant difference in allele frequencies in any SNPs in either the MBL2 or FCN2 gene in cases with early vs. late AMD. CONCLUSIONS: SNPs of lectin pathway proteins investigated in this study were not associated with AMD or AMD severity. However, MBL levels deserve further study in a larger cohort of early vs. late AMD patients to elucidate any real effect on AMD severity.

Identification of myopia-associated WNT7B polymorphisms provides insights into the mechanism underlying the development of myopia.

Myopia can cause severe visual impairment. Here, we report a two-stage genome-wide association study for three myopia-related traits in 9,804 Japanese individuals, which was extended with trans-ethnic replication in 2,674 Chinese and 2,690 Caucasian individuals. We identify WNT7B as a novel susceptibility gene for axial length (rs10453441, Pmeta=3.9 × 10(-13)) and corneal curvature (Pmeta=2.9 × 10(-40)) and confirm the previously reported association between GJD2 and myopia. WNT7B significantly associates with extreme myopia in a case-control study with 1,478 Asian patients and 4,689 controls (odds ratio (OR)meta=1.13, Pmeta=0.011). We also find in a mouse model of myopia downregulation of WNT7B expression in the cornea and upregulation in the retina, suggesting its possible role in the development of myopia.

Age-related macular degeneration phenotypes associated with mutually exclusive homozygous risk variants in CFH and HTRA1 genes.

PURPOSE: To determine age-related macular degeneration (AMD) phenotypes associated with mutually exclusive homozygotic risk variants in rs1061170 (CFH) and rs11200638 (HTRA1). METHODS: Nested case-control study of 2,982 eyes (2,129 control, 809 drusen ≥125 µm, 44 advanced AMD) homozygous for CFH [TT or CC] and HTRA1 [GG or AA] were analyzed using logistic regression and generalized estimating equations specifically regards to homozygous risk variants in one but homozygous no-risk in the other gene. RESULTS: In early AMD, [CFH HTRA1] and [CFH HTRA1] were associated with central drusen (odds ratio [95% confidence interval] = 4.13 [2.97-5.73] and 3.65 [1.88-7.09], respectively). However, only [CFH HTRA1] was associated with central drusen occupying ≥50% area (13.9 [2.97-64.7]). In advanced AMD, [CFH HTRA1] was associated with geographic atrophy (4.04 [1.57-10.4]), whereas [CFH HTRA1] was associated with neovascular AMD (36.5 [8.3-160.9]). In doubly homozygous risk groups [CFH HTRA1], odds ratios were multiplicative. CONCLUSION: Central but not peripheral drusen location was strongly associated with both [CFH HTRA1] and [CFH HTRA1]. Only [CFH HTRA1] was significantly associated with increased central drusen area.

Polymorphisms in the APOE gene and the location of retinal fluid in eyes with neovascular age-related macular degeneration.

BACKGROUND: Previous reports suggest that the outcome of age-related macular degeneration treatment is dependent on variants in the apolipoprotein E (APOE) gene. We wish to establish if variants in this gene are associated with anatomical location of fluid within the macula on optical coherence tomography imaging before and after three anti-vascular endothelial growth factor treatments. METHODS: Patients with subfoveal choroidal neovascularization secondary to age-related macular degeneration were prospectively enrolled and monitored over a 12-month period. Main outcome measures were logMAR best-corrected visual acuity and correlation of qualitative optical coherence tomography features (intraretinal fluid [IRF] and/or subretinal fluid) at baseline and after three anti-vascular endothelial growth factor injections with genetic variants of the APOE gene. RESULTS: One hundred and eighty-six eyes of 186 patients aged 79.4 years (range, 58-103 years). Subjects with an ε2 allele were more likely to have IRF at baseline compared with the eyes without (odds ratio: 2.98, 95% confidence interval: 1.22-7.29, P = 0.02). After 3 injections, 184 eyes remained. Of these, 114 of eyes (62.0%) were classified as "dry" on optical coherence tomography, whereas 48 eyes (26.1%) still had a component of IRF, and 22 (12.0%) had subretinal fluid alone. There was no statistically significant association between APOE variants and presence of persistent IRF, although there were almost double the number of subjects with ε2 (40%) who had persistent fluid compared with those with ε3/ε4 (23%) (P = 0.06). CONCLUSION: In patients with neovascular age-related macular degeneration, the presence of the ε2 allele of the APOE gene was associated with having IRF at baseline. Larger studies are required to determine if a greater proportion of those with the ε2 allele retain this fluid after three initial injections.

Association of the hepatocyte growth factor gene with keratoconus in an Australian population.

PURPOSE: A previous study has indicated suggestive association of the hepatocyte growth factor (HGF) gene with Keratoconus. We wished to assess this association in an independent Caucasian cohort as well as assess its association with corneal curvature. PARTICIPANTS: Keratoconus patients were recruited from private and public clinics in Melbourne, Australia. Non-keratoconic individuals were identified from the Genes in Myopia (GEM) study from Australia. A total of 830 individuals were used for the analysis including 157 keratoconic and 673 non keratoconic subjects. METHODS: Tag single nucleotide polymorphisms (tSNPs) were chosen to encompass the hepatocyte growth factor gene as well as 2 kb upstream of the start codon through to 2 kb downstream of the stop codon. Logistic and linear regression including age and gender as covariates were applied in statistical analysis with subsequent Bonferroni correction. RESULTS: Ten tSNPs were genotyped. Following statistical analysis and multiple testing correction, a statistically significant association was found for the tSNP rs2286194 {p = 1.1×10-(3) Odds Ratio 0.52, 95% CI--0.35, 0.77} for keratoconus. No association was found between the 10 tSNPs and corneal curvature. CONCLUSIONS: These findings provide additional evidence of significant association of the HGF gene with Keratoconus. This association does not appear to act through the corneal curvature route.

Evaluating the association between keratoconus and the corneal thickness genes in an independent Australian population.

PURPOSE: A recent genome-wide association study (GWAS) identified six loci associated with central corneal thickness that also conferred associated risk of keratoconus (KC). We aimed to assess whether genetic associations existed for these loci with KC or corneal curvature in an independent cohort of European ancestry. METHODS: In total, 157 patients with KC were recruited from public and private clinics in Melbourne, Australia, and 673 individuals without KC were identified through the Genes in Myopia study from Australia. The following six single-nucleotide polymorphisms (SNPs) that showed a statistically significant association with KC in a recent GWAS study were selected for genotyping in our cohort: rs4894535 (FNDC3B), rs1324183 (MPDZ-NF1B), rs1536482 (RXRA-COL5A1), rs7044529 (COL5A), rs2721051 (FOXO1), and rs9938149 (BANP-ZNF469). The SNPs were assessed for their association with KC or corneal curvature using logistic or linear regression methods, with age and sex included as covariates. Bonferroni corrections were applied to account for multiple testing. RESULTS: Genotyping data were available for five of the SNPs. Statistically significant associations with KC were found for the SNPs rs1324183 (P = 0.001; odds ratio [OR], 1.68) and rs9938149 (P = 0.010; OR, 1.47). Meta-analysis of previous studies yielded genome-wide significant evidence of an association for rs1324183, firmly establishing it as a KC risk variant. None of the SNPs were significantly associated with corneal curvature. CONCLUSIONS: The SNPs rs1324183 in the MPDZ-NF1B gene and rs9938149 (between BANP and ZNF4659) were associated with KC in this independent cohort, but their association was via a non-corneal curvature route.

Identification of a rare coding variant in complement 3 associated with age-related macular degeneration.

Macular degeneration is a common cause of blindness in the elderly. To identify rare coding variants associated with a large increase in risk of age-related macular degeneration (AMD), we sequenced 2,335 cases and 789 controls in 10 candidate loci (57 genes). To increase power, we augmented our control set with ancestry-matched exome-sequenced controls. An analysis of coding variation in 2,268 AMD cases and 2,268 ancestry-matched controls identified 2 large-effect rare variants: previously described p.Arg1210Cys encoded in the CFH gene (case frequency (fcase) = 0.51%; control frequency (fcontrol) = 0.02%; odds ratio (OR) = 23.11) and newly identified p.Lys155Gln encoded in the C3 gene (fcase = 1.06%; fcontrol = 0.39%; OR = 2.68). The variants suggest decreased inhibition of C3 by complement factor H, resulting in increased activation of the alternative complement pathway, as a key component of disease biology.

Association of the del443ins54 at the ARMS2 locus in Indian and Australian cohorts with age-related macular degeneration.

PURPOSE: The ARMS2/HTRA1 genes at the 10q26 locus have been associated with risk of age-related macular degeneration (AMD), with the most significantly associated variants being A69S (rs10490924), del443ins54 (EU427539) and rs11200638. We wished to explore the association of the del443ins54 in two ethnically different populations from India and Australia. METHODS: The del443ins54 was screened in a large cohort of ~1500 subjects from these two populations by a combination of PCR-based agarose gel electrophoresis and validated by resequencing. Statistical analysis comprised the calculations of allele, genotype and haplotype frequencies along with their p values and corresponding odds ratios (OR), and 95% confidence intervals (95% CI) and measures of linkage disequilibrium (LD). RESULTS: The del443ins54 was significantly associated with AMD in both the Indian (p=1.74 × 10(-13); OR = 2.80, 95%CI, 2.12-3.70) and Australian cohorts (p = 2.78 × 10(-30); OR = 3.15, 95%CI, 2.58-3.86). These associations were similar to those previously identified for the A69S and the rs11200638 variant in these populations that also exhibited high degrees of LD (D' of 0.87-0.99). A major risk haplotype of "T-indel-A" (p = 5.7 × 10(-16); OR = 3.16, 95%CI, 2.34-4.19 and p=6.33 × 10(-30); OR = 3.15, 95%CI, 2.57-3.85) and a protective haplotype of "G-wild type-G" (p=2.35 × 10(-11); OR = 0.39, 95%CI, 0.29-0.52 and p=1.02 × 10(-30); OR = 0.31, 95%CI, 0.25-0.38) were identified in the Indian and Australian cohorts, respectively. CONCLUSIONS: These data provide an independent replication of the association of del443ins54 variant in two different ethnicities, despite differences in allele and haplotype frequencies between them. High levels of LD in both populations limit further genetic dissection of this region in AMD.

Genetic influences on the outcome of anti-vascular endothelial growth factor treatment in neovascular age-related macular degeneration.

PURPOSE: To determine the association of genetic variants in known age-related macular degeneration (AMD) risk-associated genes with outcome of anti-vascular endothelial growth factor (VEGF) treatment in neovascular AMD. DESIGN: Prospective cohort study. PARTICIPANTS: We enrolled 224 consecutive patients with neovascular AMD at the Royal Victorian Eye and Ear Hospital, Australia. METHODS: Patients were treated with 3 initial monthly ranibizumab or bevacizumab injections followed by 9 months of "as required" injections based on clinician's decision at each follow-up visit according to retreatment criteria. Seventeen single nucleotide polymorphisms (SNPs) in known AMD risk-associated genes including CFH (rs800292, rs3766404, rs1061170, rs2274700 and rs393955), HTRA1 (rs11200638), CFHR1-5 (rs10922153, rs16840639, rs6667243, and rs1853883), LOC387715/ARMS2 (rs3793917 and rs10490924), C3 (rs2230199 and rs1047286), C2 (rs547154), CFB (rs641153) and F13B (rs6003) were examined. Multivariate analysis was used to determine the role of each SNP in treatment outcome. MAIN OUTCOME MEASURES: The influence of selected SNPs on mean change in visual acuity (VA) at 12 months. RESULTS: Mean baseline VA was 51 ± 16.8 Early Treatment Diabetic Retinopathy Study letters. Overall, the mean change in VA from baseline was +3.2 ± 14.9 letters at 12 months. The AA (homozygote risk) genotype at rs11200638 - HTRA1 promoter SNP (P = 0.001) and GG (homozygote risk) genotype at rs10490924 (A69S) in LOC387715/ARMS2 (P = 0.002) were each significantly associated with poorer VA outcome at 12 months after multiple correction. Mean ± standard deviation change in VA from baseline in patients with AA genotype at rs11200638 was -2.9 ± 15.2 letters after 12 months compared with +5.1 ± 14.1 letters in patients with AG or GG genotypes at this SNP. Patients with either of these genotypes were also significantly more likely to lose >15 letters after 12 months. SNPs rs11200638 and rs10490924 were in high linkage disequilibrium (r(2) = 0.92). None of the other examined SNPs was associated with outcome. CONCLUSIONS: The HTRA1 promoter SNP (rs11200638) and A69S at LOC387715/ARMS2 were associated with a poorer visual outcome for ranibizumab or bevacizumab treatment in neovascular AMD, suggesting strong pharmacogenetic associations with anti-VEGF treatment. This finding could aid in applying more individualized treatment regimens based on patients' genotype to achieve optimal treatment response in AMD. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any materials discussed in this article.

A rare functional haplotype of the P2RX4 and P2RX7 genes leads to loss of innate phagocytosis and confers increased risk of age-related macular degeneration.

Age-related macular degeneration (AMD) is a leading cause of blindness in Western countries and is diagnosed by the clinical appearance of yellow subretinal deposits called drusen. Genetic changes in immune components are clearly implicated in the pathology of this disease. We have previously shown that the purinergic receptor P2X7 can act as a scavenger receptor, mediating phagocytosis of apoptotic cells and insoluble debris. We performed a genetic association study of functional polymorphisms in the P2RX7 and P2RX4 genes in a cohort of 744 patients with AMD and 557 age-matched Caucasian control subjects. The P2X4 Tyr315Cys variant was 2-fold more frequent in patients with AMD compared to control subjects, with the minor allele predicting susceptibility to disease. Pairwise linkage disequilibrium was observed between Tyr315Cys in the P2RX4 gene and Gly150Arg in the P2RX7 gene, and these two minor alleles formed a rare haplotype that was overrepresented in patients with AMD (n=17) compared with control subjects (n=3) (odds ratio 4.05, P=0.026). Expression of P2X7 (wild type or variant 150Arg) in HEK293 cells conferred robust phagocytosis toward latex beads, whereas coexpression of the P2X7 150Arg with P2X4 315Cys variants almost completely inhibited phagocytic capacity. Fresh human monocytes harboring this heterozygous 150Arg-315Cys haplotype showed 40% reduction in bead phagocytosis. In the primate eye, immunohistochemistry indicated that P2X7 and P2X4 receptors were coexpressed on microglia and macrophages, but neither receptor was seen on retinal pigment epithelial cells. These results demonstrate that a haplotype including two rare variants in P2RX7 and P2RX4 confers a functional interaction between these two variant receptors that impairs the normal scavenger function of macrophages and microglia. Failure of this P2X7-mediated phagocytic pathway may impair removal of subretinal deposits and predispose individuals toward AMD.

Proof of concept, randomized, placebo-controlled study of the effect of simvastatin on the course of age-related macular degeneration.

BACKGROUND: HMG Co-A reductase inhibitors are ubiquitous in our community yet their potential role in age-related macular degeneration (AMD) remains to be determined. OBJECTIVES: To evaluate the effect of simvastatin on AMD progression and the effect modification by polymorphism in apolipoprotein E (ApoE) and complement factor H (CFH) genes. DESIGN: A proof of concept double-masked randomized controlled study. PARTICIPANTS: 114 participants aged 53 to 91 years, with either bilateral intermediate AMD or unilateral non-advanced AMD (with advanced AMD in fellow eye), BCVA ≥ 20/60 in at least one eye, and a normal lipid profile. INTERVENTION: Simvastatin 40 mg/day or placebo, allocated 1:1. MAIN OUTCOME MEASURES: Progression of AMD either to advanced AMD or in severity of non-advanced AMD. Results. The cumulative AMD progression rates were 70% in the placebo and 54% in the simvastatin group. Intent to treat multivariable logistic regression analysis, adjusted for age, sex, smoking and baseline AMD severity, showed a significant 2-fold decrease in the risk of progression in the simvastatin group: OR 0.43 (0.18-0.99), p = 0.047. Post-hoc analysis stratified by baseline AMD severity showed no benefit from treatment in those who had advanced AMD in the fellow eye before enrolment: OR 0.97 (0.27-3.52), p = 0.96, after adjusting for age, sex and smoking. However, there was a significant reduction in the risk of progression in the bilateral intermediate AMD group compared to placebo [adjusted OR 0.23 (0.07-0.75), p = 0.015]. The most prominent effect was observed amongst those who had the CC (Y402H) at risk genotype of the CFH gene [OR 0.08 (0.02-0.45), p = 0.004]. No evidence of harm from simvastatin intervention was detected. CONCLUSION/SIGNIFICANCE: Simvastatin may slow progression of non-advanced AMD, especially for those with the at risk CFH genotype CC (Y402H). Further exploration of the potential use of statins for AMD, with emphasis on genetic subgroups, is warranted. TRIAL REGISTRATION: Australian New Zealand Clinical Trial Registry (ANZCTR) ACTRN1260500032065.

Genetic association of refractive error and axial length with 15q14 but not 15q25 in the Blue Mountains Eye Study cohort.

PURPOSE: Myopia is a common complex condition influenced by genetic and environmental factors. Two recent genome-wide association studies have identified loci on chromosomes 15q25 and 15q14 associated with refractive error in Caucasian populations. Our study aimed to assess the association of these 2 loci with refractive error and ocular biometric measures in an independent ethnically matched Caucasian cohort. DESIGN: Genetic association study using unrelated individuals. PARTICIPANTS: Blue Mountains Eye Study (BMES) cohort. A total of 1571 individuals were included in this study. METHODS: Single nucleotide polymorphism (SNP) genotype data were collected from the BMES cohort as part of the Wellcome Trust Case Control Consortium 2. Imputation was performed using MACH version 1.1.16, and statistical analysis was conducted using PLINK. Association tests were performed at both loci using refractive error (spherical equivalent), axial length, corneal curvature, and anterior chamber depth as the phenotypes. MAIN OUTCOME MEASURES: Refractive error, axial length, corneal curvature, and anterior chamber depth. RESULTS: A total of 1571 individuals were available from the BMES for analysis. A statistically significant association for refractive error was evident for SNPs at the 15q14 locus, with P values ranging from 1.5 × 10(-2) at rs685352 to 6.4 × 10(-4) at rs560764, whereas association could not be confirmed for SNPs at the 15q25 locus, with P values ranging from 8.0 × 10(-1) to 6.4 × 10(-1). Ocular biometric analysis revealed that axial length was the most likely trait underlying the refractive error association at the 15q14 locus for SNPs rs560766 (P=0.0054), rs634990 (P=0.0086), and rs8032019 (P=0.0081). CONCLUSIONS: Our results confirm the association with refractive error at the 15q14 locus but do not support the association observed at the 15q25 locus. Axial length seemed to be a major parameter at the 15q14 locus, underscoring the importance of this locus in myopia and future clinical treatment.

Variants in the VEGFA gene and treatment outcome after anti-VEGF treatment for neovascular age-related macular degeneration.

PURPOSE: To determine the association of genetic variants of the VEGFA gene with outcome of anti-vascular endothelial growth factor (VEGF) treatment in neovascular age-related macular degeneration (AMD). DESIGN: A prospective cohort study. PARTICIPANTS: We included 201 consecutive patients receiving anti-VEGF injections for neovascular AMD. METHODS: Patients were followed over 12 months. They were treated with 3 initial monthly ranibizumab or bevacizumab injections. Thereafter, the decision to retreat was made by clinicians at each follow-up visit on the basis of retreatment criteria. Seven tagged single nucleotide polymorphisms (tSNPs) in the VEGFA gene were selected and examined. Multivariate data analysis was used to determine the role of each tSNP in treatment outcome. MAIN OUTCOME MEASURES: The influence of selected VEGFA tSNPs on visual acuity (VA) outcome at 6 months. RESULTS: Mean baseline VA was 51±17 Early Treatment Diabetic Retinopathy Study (ETDRS) letter scores. Overall, the mean change in VA from baseline was +6.5±12, +4.4±13.4, and +2.3±14.6 letters at 3, 6, and 12 months, respectively. The tSNP rs3025000 was the only SNP significantly associated (P<1 × 10(-4)) with visual outcome at 6 months with multiple correction. The presence of the T allele (TC or TT genotypes) at this tSNP predicted a better outcome of +7 letters at 6 months compared with the CC genotype. In a subgroup analysis, presence of the T allele predicted a significantly higher chance of the patients belonging to the responder group (gain of ≥5 letters from baseline) after 3, 6, and 12 months treatment (odds ratio, 2.7, 3.5, and 2.4; 95% confidence interval, 1.46-5.07, 1.82-6.71, and 1.27-4.57, respectively) than any other outcome group. CONCLUSIONS: Pharmacogenetic association with anti-VEGF treatments may influence the visual outcomes in neovascular AMD. In patients with the T allele in tSNP rs3025000, there was a significantly better visual outcome at 6 months and a greater chance of the patients belonging to the responder group with anti-VEGF treatment at 3, 6, and 12 months. The VA outcomes of patients harboring the T allele at SNP rs3025000 were comparable with those of the pivotal clinical trials but with fewer injections, making the treatment perhaps more cost effective in certain subgroups of patients. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any of the materials discussed in this article.