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.

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 ß1-3 glucosyltransferase (B3GLCT) locus through genome-wide association studies. B3GLCT mediates modification of proteins with thrombospondin type I repeats (TSR) that contain O-linked glucose ß1-3 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-ß1,3-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.

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.

GENETIC RISK FACTORS IN SEVERE, NONSEVERE AND ACUTE PHENOTYPES OF CENTRAL SEROUS CHORIORETINOPATHY.

PURPOSE: To study genetic predispositions and differences between severe chronic central serous chorioretinopathy (cCSC), nonsevere cCSC, and acute central serous chorioretinopathy (aCSC). METHODS: One hundred seventy-three severe cCSC patients, 272 nonsevere cCSC patients, 135 aCSC patients, and 1,385 control individuals were included. Eight single-nucleotide polymorphisms were genotyped in the ARMS2 (rs10490924), CFH (rs800292, rs1061170, rs1065489, rs1329428, rs2284664, rs3753394), and NR3C2 (rs2070951). Additionally, C4B gene copy numbers were analyzed. RESULTS: A significant association in 5 single-nucleotide polymorphisms in the CFH gene could be reproduced among severe cCSC patients, including rs800292 (P = 0.0014; odds ratio [OR] = 1.93; 95% confidence interval [CI] = 1.51-2.47), rs1065489 (P = 2.22 × 10; OR = 0.49; 95% CI = 0.34-0.72), rs1329428 (P = 0.001; OR = 1.89; 95% CI = 1.49-2.40), rs2284664 (P = 1.21× 10; OR = 1.65; 95% CI = 1.28-2.13), and rs3753394 (P = 6.10× 10; OR = 0.61; 95% CI = 0.46-0.81). Carrying three C4B copies was protective for severe cCSC (P = 0.001; OR = 0.29; 95% CI = 0.14-0.61). No significant differences in allele frequencies could be found among the CSC phenotypes. CONCLUSION: Acute CSC, nonsevere cCSC, and severe cCSC all showed a similar association with the CFH and C4B genes, and the three phenotypes could not be distinguished based on the genetics. This shows that despite the differences in clinical presentation and severity, there is an overlap in the genetic predisposition of different CSC phenotypes. Nongenetic factors may play a more important role in determining the clinical course of CSC.

RETINAL HYPERREFLECTIVE FOCI IN TYPE 1 DIABETES MELLITUS.

PURPOSE: To investigate hyperreflective foci (HF) on spectral-domain optical coherence tomography in patients with Type 1 diabetes mellitus across different stages of diabetic retinopathy (DR) and diabetic macular edema (DME) and to study clinical and morphological characteristics associated with HF. METHODS: Spectral-domain optical coherence tomography scans and color fundus photographs were obtained of 260 patients. Spectral-domain optical coherence tomography scans were graded for the number of HF and other morphological characteristics. The distribution of HF across different stages of DR and DME severity were studied. Linear mixed-model analysis was used to study associations between the number of HF and clinical and morphological parameters. RESULTS: Higher numbers of HF were found in patients with either stage of DME versus patients without DME (P < 0.001). A trend was observed between increasing numbers of HF and DR severity, although significance was only reached for moderate nonproliferative DR (P = 0.001) and proliferative DR (P = 0.019). Higher numbers of HF were associated with longer diabetes duration (P = 0.029), lower high-density lipoprotein cholesterol (P = 0.005), and the presence of microalbuminuria (P = 0.005). In addition, HF were associated with morphological characteristics on spectral-domain optical coherence tomography, including central retinal thickness (P = 0.004), cysts (P < 0.001), subretinal fluid (P = 0.001), and disruption of the external limiting membrane (P = 0.018). CONCLUSION: The number of HF was associated with different stages of DR and DME severity. The associations between HF and clinical and morphological characteristics can be of use in further studies evaluating the role of HF as a biomarker for disease progression and treatment response.

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.

GENETIC RISK FACTORS IN ACUTE CENTRAL SEROUS CHORIORETINOPATHY.

PURPOSE: To investigate genetic associations in white patients with acute central serous chorioretinopathy (aCSC) and to assess genetic differences between aCSC and chronic CSC (cCSC). METHODS: A total of 135 aCSC patients, 272 cCSC patients, and 1,385 control individuals were included. Eight single nucleotide polymorphisms were genotyped for ARMS2 (rs10490924), CFH (rs800292, rs1061170, rs1065489, rs1329428, rs2284664, rs3753394), and NR3C2 (rs2070951). Also, C4B gene copy numbers were analyzed. RESULTS: Three single nucleotide polymorphisms in the CFH gene were significantly associated with aCSC: rs800292 (P = 0.003, odds ratio = 1.53 [95% confidence interval = 1.15-2.03]), rs1061170 (P = 0.002, odds ratio = 0.64 [95% confidence interval = 0.48-0.86]), and rs1329428 (P = 5.87 × 10, odds ratio = 1.83 [95% confidence interval = 1.40-2.38]). A significant difference was found in the distribution of C4B gene copy numbers in aCSC patients compared with controls (P = 0.0042). No differences could be found among the selected variants between aCSC and cCSC patients. CONCLUSION: Three variants in the CFH gene and copy number variations in C4B were found to be significantly associated with the risk of aCSC development. Despite the differences in clinical presentation, acute and chronic CSC may share a similar genetic predisposition based on our present analysis. Other genetic and/or nongenetic risk factors may be more influential in the differentiation toward an acute or a chronic phenotype of CSC.

ADALIMUMAB THERAPY FOR REFRACTORY BIRDSHOT CHORIORETINOPATHY.

PURPOSE: To report the outcome of using adalimumab to treat birdshot chorioretinopathy. METHODS: Retrospective case series of 19 patients (38 eyes) with HLA-A29-positive birdshot chorioretinopathy who received adalimumab treatment. Patients had been refractory to previous standard systemic immunomodulatory therapy. They received biweekly subcutaneous injections of 40 mg of adalimumab. Outcome measures were change in visual acuity, fluorescein angiography, and optical coherence tomography features, the concomitant use of immunosuppressive drugs, and the occurrence of adverse effects between 1 year before, at baseline, and after 1 year of adalimumab treatment. RESULTS: Mean Snellen visual acuity at 1-year follow-up was 20/28, an improvement from 20/43 at the start of the treatment (P = 0.011) and equal to the visual acuity 1 year before the treatment (20/29). Only 2 of the 9 patients who had complete fluorescein angiography and optical coherence tomography results after the 1 year of treatment were completely free of inflammation signs at the end of the follow-up. Half (53%) of 17 patients were receiving adalimumab monotherapy after 1 year of treatment, an increase from 21% at the start of treatment (P = 0.047). Three of the 19 patients reported possible side effects; 2 discontinued treatment within 1 year. CONCLUSION: The results suggest that adalimumab is effective at improving visual acuity and at tapering concomitant immunomodulatory therapy, in patients with refractory birdshot chorioretinopathy. However, complete remission is rarely achieved.

FAMILIAL CENTRAL SEROUS CHORIORETINOPATHY.

PURPOSE: To assess ophthalmologic characteristics in patients and unaffected individuals in families with multiple members affected by central serous chorioretinopathy (CSC), both at presentation and long-term follow-up. METHODS: In 103 subjects from 23 families with at least 2 affected patients with CSC per family, prospective extensive ophthalmologic examination was performed, including best-corrected visual acuity, indirect ophthalmoscopy, digital color fundus photography, optical coherence tomography, fundus autofluorescence, and fluorescein angiography imaging. From these, 24 individuals from 6 families had undergone extensive ophthalmologic examination in either 1994 or 1995 and were followed up in this study. RESULTS: Subretinal fluid accumulation on optical coherence tomography and/or "hot spots" of leakage on fluorescein angiography indicative of CSC were detected in 45 of 103 phenotyped subjects (44%). Findings suggestive of CSC, but without the presence of subretinal fluid on optical coherence tomography and/or "hot spots" of leakage on fluorescein angiography, were observed in an additional 27 family members (26%). In 4 of 17 previously nonaffected subjects (24%) from the 24 individuals that were followed up after more than 20 years, we found more severe abnormalities. CONCLUSION: Extensive ophthalmologic phenotyping resulted in the detection of (suggestive) CSC in 52% of family members of patients with CSC. Genetic factors may play an important role in these specific CSC cases. Moreover, during follow-up, progressive disease can occur in a noteworthy number of patients.

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.

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 (Pdiscovery = 1.09 × 10-15; Pmeta = 3.66 × 10-21; ß = 0.141; standard error [SE] = 0.015) and rs6685931 located in CFHR4 (Pdiscovery = 8.18 × 10-7; Pmeta = 6.32 × 10-8; ß = 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; ß = 0.183; SE = 0.024; and P = 4.28 × 10-4; ß = 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.

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.

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.

A genetic variant in NRP1 is associated with worse response to ranibizumab treatment in neovascular age-related macular degeneration.

OBJECTIVE: The aim of the study was to investigate the role of single-nucleotide polymorphisms (SNPs) located in the neuropilin-1 (NRP1) gene in treatment response to antivascular endothelial growth factor (VEGF) therapy for neovascular age-related macular degeneration (nvAMD). METHODS: Four SNPs in the NRP1 gene (rs2229935, rs2247383, rs2070296, and rs2804495) were genotyped in a study cohort of 377 nvAMD patients who received the loading dose of three monthly ranibizumab injections. Treatment response was assessed as the change in visual acuity after three monthly loading injections compared with baseline. RESULTS: SNP rs2070296 was associated with change in visual acuity after 3 months of treatment. Patients carrying the GA or AA genotypes performed significantly worse than individuals carrying the GG genotype (P=0.01). A cumulative effect of rs2070296 in the NRP1 gene and rs4576072 located in the VEGF receptor 2 (VEGFR2 or KDR) gene, previously associated with treatment response, was observed. Patients carrying two risk alleles performed significantly worse than patients carrying zero or one risk allele (P=0.03), and patients with more than two risk alleles responded even worse to the therapy (P=3×10). The combined effect of these two SNPs on the response was also seen after 6 and 12 months of treatment. CONCLUSION: This study suggests that genetic variation in NRP1, a key molecule in VEGFA-driven neovascularization, influences treatment response to ranibizumab in nvAMD patients. The results of this study may be used to generate prediction models for treatment response, which in the future may help tailor medical care to individual needs.

Central serous chorioretinopathy in primary hyperaldosteronism.

PURPOSE: To describe ophthalmological characteristics of 13 patients with primary hyperaldosteronism (PA). METHODS: Cross-sectional study. All patients underwent extensive ophthalmological examination. RESULTS: Thirteen PA patients (9 male, 4 female) were diagnosed with arterial hypertension for 11.0 ± 11.2 years. Ophthalmological imaging revealed macular serous subretinal fluid (SRF) on optical coherence tomography in 2 patients (15 %). In one of these patients, bilateral chronic central serous chorioretinopathy (CSC) with polypoidal choroidal neovasculopathy was diagnosed, which was effectively treated with full-dose photodynamic therapy. In the other patient with SRF and bilateral diffuse hyperfluorescent areas on fluorescein angiography, the SRF had decreased spontaneously after 6 weeks of follow-up. In 5 of the remaining patients (38 %), retinal pigment epithelium alterations resembling findings characteristic for CSC were seen on multimodal imaging. The mean subfoveal choroidal thickness was 290.2 ± 65.0 µm. CONCLUSIONS: Retinal abnormalities resembling (subclinical) CSC are common in patients with PA. These findings indicate that mineralocorticoid-mediated pathways are involved in the pathogenesis of CSC. In CSC patients with hypertension of unknown origin, a diagnosis of PA should be considered.

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.

Chronic central serous chorioretinopathy is associated with genetic variants implicated in age-related macular degeneration.

PURPOSE: In this study, single nucleotide polymorphisms (SNPs) at 19 loci, previously associated with age-related macular degeneration (AMD), were systematically tested for association in patients with chronic central serous chorioretinopathy (cCSC). In addition, we evaluated the effect of detailed phenotyping on these genetic associations. DESIGN: Case-control study. PARTICIPANTS: We included 292 cCSC patients, 1147 AMD patients, and 1311 control individuals. METHODS: We genotyped SNPs at 19 AMD-associated loci and 6 additional SNPs at the complement factor H (CFH) locus. Phenotyping of all patients was based on fundoscopy, spectral-domain optical coherence tomography, fluorescein angiography (FA), and indocyanine green angiography. MAIN OUTCOME MEASURES: We measured the allele frequencies of 25 AMD-associated SNPs and CFH haplotype frequencies in patients with cCSC and the effect of phenotypic subdivision of cCSC on genetic associations. RESULTS: One SNP in ARMS2 (rs10490924) was significant after Bonferroni correction (Punadjusted=0.002; odds ratio [OR]=0.64). The SNPs at 3 other AMD loci (CFH, TNFRSF10A, ADAMTS9) showed a trend toward association with typical cCSC. Further analysis of the CFH locus identified 2 SNPs that significantly conferred increased risk for cCSC and 1 that was protective. The CFH-H3 haplotype was also found to be protective (P=0.01; OR=0.54). Using multimodal imaging, 197 patients were classified as having typical cCSC, 52 patients had unilateral abnormalities on FA that were otherwise typical of cCSC, and 43 patients had a clinical picture that could be compatible with cCSC, but with features that could also indicate other macular diseases. Significant differences of the minor allele frequencies of the tested SNPs were observed between these 3 phenotypic subgroups. CONCLUSIONS: Chronic CSC is associated with genetic variants in ARMS2 and CFH, indicating a genetic and pathophysiologic overlap between cCSC and AMD. Intriguingly, alleles in ARMS2 and CFH that confer risk of AMD may be protective for cCSC, and alleles in CFH that are protective for AMD confer risk for cCSC. Significant differences in allele frequencies were found among the phenotypic subgroups for several SNPs, illustrating the importance of correct clinical classification.

Epigenetic regulation of learning and memory by Drosophila EHMT/G9a.

The epigenetic modification of chromatin structure and its effect on complex neuronal processes like learning and memory is an emerging field in neuroscience. However, little is known about the "writers" of the neuronal epigenome and how they lay down the basis for proper cognition. Here, we have dissected the neuronal function of the Drosophila euchromatin histone methyltransferase (EHMT), a member of a conserved protein family that methylates histone 3 at lysine 9 (H3K9). EHMT is widely expressed in the nervous system and other tissues, yet EHMT mutant flies are viable. Neurodevelopmental and behavioral analyses identified EHMT as a regulator of peripheral dendrite development, larval locomotor behavior, non-associative learning, and courtship memory. The requirement for EHMT in memory was mapped to 7B-Gal4 positive cells, which are, in adult brains, predominantly mushroom body neurons. Moreover, memory was restored by EHMT re-expression during adulthood, indicating that cognitive defects are reversible in EHMT mutants. To uncover the underlying molecular mechanisms, we generated genome-wide H3K9 dimethylation profiles by ChIP-seq. Loss of H3K9 dimethylation in EHMT mutants occurs at 5% of the euchromatic genome and is enriched at the 5' and 3' ends of distinct classes of genes that control neuronal and behavioral processes that are corrupted in EHMT mutants. Our study identifies Drosophila EHMT as a key regulator of cognition that orchestrates an epigenetic program featuring classic learning and memory genes. Our findings are relevant to the pathophysiological mechanisms underlying Kleefstra Syndrome, a severe form of intellectual disability caused by mutations in human EHMT1, and have potential therapeutic implications. Our work thus provides novel insights into the epigenetic control of cognition in health and disease.

CNTNAP2 and NRXN1 are mutated in autosomal-recessive Pitt-Hopkins-like mental retardation and determine the level of a common synaptic protein in Drosophila.

Heterozygous copy-number variants and SNPs of CNTNAP2 and NRXN1, two distantly related members of the neurexin superfamily, have been repeatedly associated with a wide spectrum of neuropsychiatric disorders, such as developmental language disorders, autism spectrum disorders, epilepsy, and schizophrenia. We now identified homozygous and compound-heterozygous deletions and mutations via molecular karyotyping and mutational screening in CNTNAP2 and NRXN1 in four patients with severe mental retardation (MR) and variable features, such as autistic behavior, epilepsy, and breathing anomalies, phenotypically overlapping with Pitt-Hopkins syndrome. With a frequency of at least 1% in our cohort of 179 patients, recessive defects in CNTNAP2 appear to significantly contribute to severe MR. Whereas the established synaptic role of NRXN1 suggests that synaptic defects contribute to the associated neuropsychiatric disorders and to severe MR as reported here, evidence for a synaptic role of the CNTNAP2-encoded protein CASPR2 has so far been lacking. Using Drosophila as a model, we now show that, as known for fly Nrx-I, the CASPR2 ortholog Nrx-IV might also localize to synapses. Overexpression of either protein can reorganize synaptic morphology and induce increased density of active zones, the synaptic domains of neurotransmitter release. Moreover, both Nrx-I and Nrx-IV determine the level of the presynaptic active-zone protein bruchpilot, indicating a possible common molecular mechanism in Nrx-I and Nrx-IV mutant conditions. We therefore propose that an analogous shared synaptic mechanism contributes to the similar clinical phenotypes resulting from defects in human NRXN1 and CNTNAP2.