RETINITIS PIGMENTOSA ASSOCIATED WITH THE EYS C2139Y VARIANT : An Important Cause of Blindness in East Asian Populations.

PURPOSE: The study aimed to describe the phenotypic features of retinitis pigmentosa (RP) associated with the previously described EYS C2139Y variant in Singaporeans and establish the importance of this variant as a prevalent cause of RP among East Asians. METHODS: A clinical phenotyping and exome-sequencing study was conducted on consecutive patients with nonsyndromic RP. Epidemiological analysis was performed using Singaporean and global population-based genetic data. RESULTS: A study of 150 consecutive unrelated individuals with nonsyndromic RP found that 87 (58%) of cases had plausible genotypes. A previously described missense variant in the EYS gene, 6416G>A (C2139Y), occurred heterozygously or homozygously in 17 of 150 families (11.3%), all with autosomal recessive RP. Symptom onset in EYS C2139Y-related RP ranged from 6 to 45 years, with visual acuity ranging from 20/20 at 21 years to no light perception by 48 years. C2139Y-related RP had typical findings, including sectoral RP in cases with EYS E2703X in trans . The median age at presentation was 45 years and visual fields declined to less than 20° (Goldmann V4e isopter) by age 65 years. Intereye correlation for visual acuity, fields, and ellipsoid band width was high (r 2 = 0.77-0.95). Carrier prevalence was 0.66% (allele frequency of 0.33%) in Singaporean Chinese and 0.34% in East Asians, suggesting a global disease burden exceeding 10,000 individuals. CONCLUSION: The EYS C2139Y variant is common in Singaporean RP patients and other ethnic Chinese populations. Targeted molecular therapy for this single variant could potentially treat a significant proportion of RP cases worldwide.

Evaluation of Generative Adversarial Networks for High-Resolution Synthetic Image Generation of Circumpapillary Optical Coherence Tomography Images for Glaucoma.

Importance: Deep learning (DL) networks require large data sets for training, which can be challenging to collect clinically. Generative models could be used to generate large numbers of synthetic optical coherence tomography (OCT) images to train such DL networks for glaucoma detection. Objective: To assess whether generative models can synthesize circumpapillary optic nerve head OCT images of normal and glaucomatous eyes and determine the usability of synthetic images for training DL models for glaucoma detection. Design, Setting, and Participants: Progressively growing generative adversarial network models were trained to generate circumpapillary OCT scans. Image gradeability and authenticity were evaluated on a clinical set of 100 real and 100 synthetic images by 2 clinical experts. DL networks for glaucoma detection were trained with real or synthetic images and evaluated on independent internal and external test data sets of 140 and 300 real images, respectively. Main Outcomes and Measures: Evaluations of the clinical set between the experts were compared. Glaucoma detection performance of the DL networks was assessed using area under the curve (AUC) analysis. Class activation maps provided visualizations of the regions contributing to the respective classifications. Results: A total of 990 normal and 862 glaucomatous eyes were analyzed. Evaluations of the clinical set were similar for gradeability (expert 1: 92.0%; expert 2: 93.0%) and authenticity (expert 1: 51.8%; expert 2: 51.3%). The best-performing DL network trained on synthetic images had AUC scores of 0.97 (95% CI, 0.95-0.99) on the internal test data set and 0.90 (95% CI, 0.87-0.93) on the external test data set, compared with AUCs of 0.96 (95% CI, 0.94-0.99) on the internal test data set and 0.84 (95% CI, 0.80-0.87) on the external test data set for the network trained with real images. An increase in the AUC for the synthetic DL network was observed with the use of larger synthetic data set sizes. Class activation maps showed that the regions of the synthetic images contributing to glaucoma detection were generally similar to that of real images. Conclusions and Relevance: DL networks trained with synthetic OCT images for glaucoma detection were comparable with networks trained with real images. These results suggest potential use of generative models in the training of DL networks and as a means of data sharing across institutions without patient information confidentiality issues.

Comparison of machine learning approaches for structure-function modeling in glaucoma.

To evaluate machine learning (ML) approaches for structure-function modeling to estimate visual field (VF) loss in glaucoma, models from different ML approaches were trained on optical coherence tomography thickness measurements to estimate global VF mean deviation (VF MD) and focal VF loss from 24-2 standard automated perimetry. The models were compared using mean absolute errors (MAEs). Baseline MAEs were obtained from the VF values and their means. Data of 832 eyes from 569 participants were included, with 537 Asian eyes for training, and 148 Asian and 111 Caucasian eyes set aside as the respective test sets. All ML models performed significantly better than baseline. Gradient-boosted trees (XGB) achieved the lowest MAE of 3.01 (95% CI: 2.57, 3.48) dB and 3.04 (95% CI: 2.59, 3.99) dB for VF MD estimation in the Asian and Caucasian test sets, although difference between models was not significant. In focal VF estimation, XGB achieved median MAEs of 4.44 [IQR 3.45-5.17] dB and 3.87 [IQR 3.64-4.22] dB across the 24-2 VF for the Asian and Caucasian test sets and was comparable to VF estimates from support vector regression (SVR) models. VF estimates from both XGB and SVR were significantly better than the other models. These results show that XGB and SVR could potentially be used for both global and focal structure-function modeling in glaucoma.

Association of peripheral anterior synechiae with anterior segment parameters in eyes with primary angle closure glaucoma.

To investigate the association of peripheral anterior synechiae (PAS) with intraocular pressure (IOP) and anterior-segment parameters in subjects with primary angle-closure glaucoma (PACG). A total of 267 subjects with PACG were recruited and underwent gonioscopy and anterior-segment optical coherence tomography (ASOCT). Customized software was used to measure ASOCT parameters, including angle opening distance (AOD750) and trabecular-iris-space-area (TISA750) at 750 µm from the scleral spur, anterior chamber depth, width, area and volume (ACD, ACW, ACA, ACV), iris thickness (IT750), iris area (IAREA), and lens vault (LV). Presenting IOP was defined as the first IOP reading before the initiation of IOP-lowering treatment. The mean age of the 267 subjects was 67.0 ± 8.9 years, 140 (52.4%) were male, and 246 (92.1%) were of Chinese ethnicity. PAS was present in 122 (45.7%) subjects, and was most frequently found in the superior quadrant (79.5%). Subjects with PAS had greater presenting IOP (28.7 ± 12.9 vs 22.4 ± 9.7 mmHg, p < 0.001), narrower AOD750 (p < 0.001), smaller TISA750 (p < 0.001), ACD (p = 0.04), ACA (p = 0.02), ACV (p = 0.01) and larger LV (p = 0.01) compared to PACG eyes without PAS. No significant differences were noted for iris parameters. A multivariate logistic regression analysis showed that higher presenting IOP (ß = 0.20, p < 0.001), worse visual field mean deviation (ß = - 0.20, p = 0.01) and narrower AOD750 (ß = - 0.25, p = 0.03) were the only parameters that significantly correlated with the extent of PAS in clock hours. Almost one-half of the subjects with PACG demonstrated PAS; these eyes were associated with higher presenting IOP, smaller anterior segment dimensions and more severe disease.

Genome-wide meta-analysis identifies 127 open-angle glaucoma loci with consistent effect across ancestries.

Primary open-angle glaucoma (POAG), is a heritable common cause of blindness world-wide. To identify risk loci, we conduct a large multi-ethnic meta-analysis of genome-wide association studies on a total of 34,179 cases and 349,321 controls, identifying 44 previously unreported risk loci and confirming 83 loci that were previously known. The majority of loci have broadly consistent effects across European, Asian and African ancestries. Cross-ancestry data improve fine-mapping of causal variants for several loci. Integration of multiple lines of genetic evidence support the functional relevance of the identified POAG risk loci and highlight potential contributions of several genes to POAG pathogenesis, including SVEP1, RERE, VCAM1, ZNF638, CLIC5, SLC2A12, YAP1, MXRA5, and SMAD6. Several drug compounds targeting POAG risk genes may be potential glaucoma therapeutic candidates.

Factors affecting the diagnostic performance of circumpapillary retinal nerve fibre layer measurement in glaucoma.

BACKGROUND/AIMS: To identify factors that influence the diagnostic performance of circumpapillary retinal nerve fibre layer (RNFL) thickness measurements in the detection of primary open-angle glaucoma (POAG). METHODS: 1592 eyes from 1076 healthy controls and 758 eyes from 502 patients with POAG underwent optical coherence tomography (OCT) imaging to assess RNFL parameters. Visual field (VF) mean deviation (MD) from standard automated perimetry was used to indicate severity in subjects with glaucoma. RESULTS: RNFL thickness significantly decreased with age (ρ=-0.10 to -0.16, p<0.001) and increased with spherical equivalent (SE) refractive error (ρ=0.23-0.29, p<0.001) in healthy and glaucoma groups but showed a significant reduction with SE (ρ=-0.20, p<0.001) in the temporal RNFL of healthy subjects. RNFL measurements significantly decreased with VF MD (ρ=0.08-0.53, p<0.05) in subjects with POAG. When healthy subjects and subjects with glaucoma were matched to subgroups within a factor, significant differences in area under the curve (AUC) between subgroups were only found with SE AUCs increased significantly with disease severity, particularly in the global, inferior and superior measurements (p<0.001). Overall, the diagnostic performance of the inferior and global RNFL measurements were found to be more resilient to different factors. CONCLUSION: Diagnostic accuracy in glaucoma was influenced by SE but could be mitigated by using controls with similar refractive characteristics. Increasing disease severity led to significantly better diagnostic accuracy. These factors should be considered when using OCT for glaucoma diagnosis in practice.

Evaluation of Primary Angle-Closure Glaucoma Susceptibility Loci for Estimating Angle Closure Disease Severity.

PURPOSE: To investigate whether recently identified genetic loci for primary angle-closure glaucoma (PACG) are associated with disease severity. DESIGN: Case-control study. PARTICIPANTS: Eight hundred four PACG patients and 943 control participants of Chinese ethnicity from Singapore. METHODS: The 8 PACG-associated single nucleotide polymorphisms (SNPs; rs11024102 at PLEKHA7, rs3753841 at COL11A1, rs1015213 located between PCMTD1 and ST18 on chromosome 8q, rs3816415 at EPDR1, rs1258267 at CHAT, rs736893 at GLIS3, rs7494379 at FERMT2, and rs3739821 mapping in between DPM2 and FAM102A) identified from genome-wide association studies were tested for association with disease severity using logistic regression adjusted for age and gender. A P value of 0.006 was set as significant after Bonferroni correction for testing of 8 loci. We also calculated the weighted genetic risk score (GRS) weighted by the estimated individual SNP effect size on PACG calculated as logarithm of the odds ratio (OR). Disease severity was based on the visual field mean deviation (MD) and classified as early to moderate (MD, >-12 dB) and severe (MD, <-20 dB). MAIN OUTCOME MEASURES: Association of PACG loci with severe disease. RESULTS: Of the 804 PACG patients, genotyping data were available for 768 individuals and included 436 with mild-to-moderate PACG and 206 with severe PACG. The PACG patients were significantly older (mean age, 64.3 ± 9.1 years vs. 56.4 ± 8.9 years; P < 0.001) and there were proportionately more women compared with control participants (58.4% vs. 49.0%; P < 0.001). Of the 8 loci investigated, we observed significant evidence of association with severe PACG at 1 SNP, namely rs3816415 in EPDR1 (OR, 2.03; 95% confidence interval [CI], 1.49-2.78; P = 1 × 10-5). A higher-weighted GRS was associated significantly with severe PACG, with an OR of 3.11 (95% CI, 1.95-4.96) comparing the lowest quartile with the highest quartile. CONCLUSIONS: Our results show that EPDR1 is associated significantly with severe PACG, suggesting that it may predispose patients to more aggressive disease development. Individuals with PACG with a higher GRS were associated with a higher risk of severe PACG.

Common variants in SOX-2 and congenital cataract genes contribute to age-related nuclear cataract.

Nuclear cataract is the most common type of age-related cataract and a leading cause of blindness worldwide. Age-related nuclear cataract is heritable (h2 = 0.48), but little is known about specific genetic factors underlying this condition. Here we report findings from the largest to date multi-ethnic meta-analysis of genome-wide association studies (discovery cohort N = 14,151 and replication N = 5299) of the International Cataract Genetics Consortium. We confirmed the known genetic association of CRYAA (rs7278468, P = 2.8 × 10-16) with nuclear cataract and identified five new loci associated with this disease: SOX2-OT (rs9842371, P = 1.7 × 10-19), TMPRSS5 (rs4936279, P = 2.5 × 10-10), LINC01412 (rs16823886, P = 1.3 × 10-9), GLTSCR1 (rs1005911, P = 9.8 × 10-9), and COMMD1 (rs62149908, P = 1.2 × 10-8). The results suggest a strong link of age-related nuclear cataract with congenital cataract and eye development genes, and the importance of common genetic variants in maintaining crystalline lens integrity in the aging eye.

Primary angle closure glaucoma genomic associations and disease mechanism.

PURPOSE OF REVIEW: The genetic basis of primary angle closure (PAC) glaucoma is slowly being elucidated. In recent years, genome-wide association studies have identified eight new susceptibility loci for PAC. Our purpose in this review is to summarize our current knowledge of genetics in angle closure, to take a closer look at the eight novel loci and what we have learned about their function, and consider what they might teach us about angle closure disease. RECENT FINDINGS: Multiple novel loci associated with PAC glaucoma have been identified in large genome-wide association studies. Moreover, primary open angle glaucoma and PAC glaucoma are found to have partly overlapping genetic features. SUMMARY: The genetic basis of PAC glaucoma is being deciphered. Even though there is still much more to be uncovered, this process has already provided new insights in the pathogenesis of this blinding disease. A better understanding of the pathogenic mechanisms through genomics may be valuable for the development of novel therapies.

Integration of Genetic and Biometric Risk Factors for Detection of Primary Angle Closure Glaucoma.

PURPOSE: The purpose of this study was to investigate whether the addition of primary angle closure glaucoma (PACG)-associated genetic loci allows improved detection of PACG, compared to anterior segment parameters measured by imaging. DESIGN: Case-control study. METHODS: Genotype data of the 8 PACG single-nucleotide polymorphisms (SNPs) (rs11024102 at PLEKHA7, rs3753841 at COL11A1, rs1015213 located between PCMTD1 and ST18 on Chromosome 8q, rs3816415 at EPDR1, rs1258267 at CHAT, rs736893 at GLIS3, rs7494379 at FERMT2, and rs3739821 mapping in between DPM2 and FAM102A) were available. Customized software was used to measure anterior segment optical coherence tomography (ASOCT) parameters, namely, anterior chamber depth, width, and area (ACD, ACW, and ACA) and lens vault (LV). Statistical analysis for positive predictive values was modeled using the receiver operating characteristic curve (AUC). Statistical significance comparing predictive power of the different parameters was calculated using permutation. RESULTS: A total of 388 PACG subjects and 751 controls with both ASOCT and genetic data were available for analysis. Anterior segment parameters including ACD, ACA, and LV had excellent predictive value (AUCs >0.94), except ACW (AUC=0.65), for identifying PACG. The inclusion of genetic risk alleles (either singly or as a composite genetic risk score for 8 genomewide association study SNPs) to ACD only provided a +0.50% improvement in reclassifying PACG cases and controls over and above the discriminatory value of ACD. This +0.50% improvement was not statistically significant (P > .05). CONCLUSIONS: Although significant on their own, the incorporation of genetic data in the context of anterior segment imaging parameters like ACD provided only a marginal improvement of PACG detection.

In-utero epigenetic factors are associated with early-onset myopia in young children.

OBJECTIVES: To assess whether epigenetic mechanisms affecting gene expression may be involved in the pathogenesis of early-onset myopia, we performed genome-wide DNA methylation analyses of umbilical cord tissues, and assessed any associations between CpG site-specific methylation and the development of the disorder when the children were 3 years old. METHODS: Genome-wide DNA methylation profiling of umbilical cord samples from 519 Singaporean infants involved in a prospective birth cohort 'Growing Up in Singapore Towards healthy Outcomes' (GUSTO) was performed using the Illumina Infinium HumanMethylation450K chip microarray. Multivariable logistic regression models were used to assess any associations between site-specific CpG methylation of umbilical cord tissue at birth and myopia risk in 3 year old children, adjusting for potential confounders. Gene expression of genes located near CpG sites that demonstrated statistically significant associations were measured in relevant ocular tissues using human and mouse fetal and adult eye samples. RESULTS: We identified statistically significant associations between DNA methylation levels at five CpG sites and early-onset myopia risk after correcting for multiple comparisons using a false discovery rate of 5%. Two statistically significant CpG sites were identified in intergenic regions: 8p23(p = 1.70×10-7) and 12q23.2(p = 2.53×10-7). The remaining 3 statistically significant CpG sites were identified within the following genes: FGB (4q28, p = 3.60×10-7), PQLC1 (18q23, p = 8.9×10-7) and KRT12 (17q21.2, p = 1.2×10-6). Both PQLC1 and KRT12 were found to be significantly expressed in fetal and adult cornea and sclera tissues in both human and mouse. CONCLUSIONS: We identified five CpG methylation sites that demonstrate a statistically significant association with increased risk of developing early-onset myopia. These findings suggest that variability in the neonatal cord epigenome may influence early-onset myopia risk in children. Further studies of the epigenetic influences on myopia risk in larger study populations, and the associations with adulthood myopia risk are warranted.

Trinucleotide repeat expansion length as a predictor of the clinical progression of Fuchs' Endothelial Corneal Dystrophy.

PURPOSE: To determine if CTG18.1 TNR expansion length prognosticates the clinical progression of Fuchs' Endothelial Corneal Dystrophy (FECD). METHODS: This was a prospective cohort study. A total of 51 patients with newly diagnosed FECD were recruited and followed-up over a period of 12 years, from November 2004 to April 2016. Baseline clinical measurements included central corneal thickness (CCT), endothelial cell density (ECD) and CTG18.1 TNR expansion length from peripheral leukocytes, with yearly repeat measurements of CCT and ECD. A patient was defined to have experienced significant clinical progression and to have developed Threshold Disease if any of these criteria were fulfilled in either eye: a) CCT increased to >700µm, b) ECD decreased to <700 cells/mm2, or c) underwent keratoplasty for treatment of FECD. RESULTS: Patients were categorized as having at least one allele whose maximum allele length was equal to or greater than 40 repeats (L≥40, n = 22, 43.1%), or having both alleles shorter than 40 repeats (L<40). Threshold Disease rates at the 5-year time point were 87.5% for the L≥40 group and 47.8% for the L<40 group (p = 0.012). This difference narrowed and was no longer statistically significant at the 8-years (92.9% vs 78.9%, p = 0.278) and 10-years (92.9% vs 84.2%, p = 0.426) time points. CONCLUSIONS: L≥40 patients are at greater risk of FECD progression and development of Threshold Disease within the first 5 years following diagnosis.

Author Correction: Cross-ancestry genome-wide association analysis of corneal thickness strengthens link between complex and Mendelian eye diseases.

Emmanuelle Souzeau, who contributed to analysis of data, was inadvertently omitted from the author list in the originally published version of this Article. This has now been corrected in both the PDF and HTML versions of the Article.

Cross-ancestry genome-wide association analysis of corneal thickness strengthens link between complex and Mendelian eye diseases.

Central corneal thickness (CCT) is a highly heritable trait associated with complex eye diseases such as keratoconus and glaucoma. We perform a genome-wide association meta-analysis of CCT and identify 19 novel regions. In addition to adding support for known connective tissue-related pathways, pathway analyses uncover previously unreported gene sets. Remarkably, >20% of the CCT-loci are near or within Mendelian disorder genes. These included FBN1, ADAMTS2 and TGFB2 which associate with connective tissue disorders (Marfan, Ehlers-Danlos and Loeys-Dietz syndromes), and the LUM-DCN-KERA gene complex involved in myopia, corneal dystrophies and cornea plana. Using index CCT-increasing variants, we find a significant inverse correlation in effect sizes between CCT and keratoconus (r = -0.62, P = 5.30 × 10-5) but not between CCT and primary open-angle glaucoma (r = -0.17, P = 0.2). Our findings provide evidence for shared genetic influences between CCT and keratoconus, and implicate candidate genes acting in collagen and extracellular matrix regulation.

Genome-wide association study identifies seven novel susceptibility loci for primary open-angle glaucoma.

Primary open-angle glaucoma (POAG) is the leading cause of irreversible blindness worldwide for which 15 disease-associated loci had been discovered. Among them, only 5 loci have been associated with POAG in Asians. We carried out a genome-wide association study and a replication study that included a total of 7378 POAG cases and 36 385 controls from a Japanese population. After combining the genome-wide association study and the two replication sets, we identified 11 POAG-associated loci, including 4 known (CDKN2B-AS1, ABCA1, SIX6 and AFAP1) and 7 novel loci (FNDC3B, ANKRD55-MAP3K1, LMX1B, LHPP, HMGA2, MEIS2 and LOXL1) at a genome-wide significance level (P < 5.0×10-8), bringing the total number of POAG-susceptibility loci to 22. The 7 novel variants were subsequently evaluated in a multiethnic population comprising non-Japanese East Asians (1008 cases, 591 controls), Europeans (5008 cases, 35 472 controls) and Africans (2341 cases, 2037 controls). The candidate genes located within the new loci were related to ocular development (LMX1B, HMGA2 and MAP3K1) and glaucoma-related phenotypes (FNDC3B, LMX1B and LOXL1). Pathway analysis suggested epidermal growth factor receptor signaling might be involved in POAG pathogenesis. Genetic correlation analysis revealed the relationships between POAG and systemic diseases, including type 2 diabetes and cardiovascular diseases. These results improve our understanding of the genetic factors that affect the risk of developing POAG and provide new insight into the genetic architecture of POAG in Asians.

Evaluation of Primary Angle-Closure Glaucoma Susceptibility Loci in Patients with Early Stages of Angle-Closure Disease.

PURPOSE: To investigate whether newly identified genetic loci for primary angle-closure glaucoma (PACG) are associated with early stage angle-closure disease defined as primary angle closure suspect (PACS). DESIGN: Case-control study. PARTICIPANTS: A total of 1397 PACS patients and 943 controls of Chinese ethnicity from Singapore and 604 PACS patients and 287 controls of Indian ethnicity. METHODS: The 8 PACG single nucleotide polymorphisms (SNPs; rs11024102 at PLEKHA7, rs3753841 at COL11A1, rs1015213 located between PCMTD1 and ST18 son chromosome 8q, rs3816415 at EPDR1, rs1258267 at CHAT, rs736893 at GLIS3, rs7494379 at FERMT2, and rs3739821 mapping in between DPM2 and FAM102A) were genotyped by Taqman assays. The association between SNP genotypes and PACS status was measured using logistic regression. A P value of 0.006 was set to account for the testing of 8 genetic loci using a Bonferroni correction. A meta-analysis was conducted to calculate the overall P value and accompanying per-allele odds ratios for each SNP analyzed. MAIN OUTCOME MEASURES: Association of PACG loci with PACS status. RESULTS: The PACS patients were significantly older in both cohorts (Chinese, P < 0.001; Indian, P = 0.002), and there were also more women (P < 0.001, both Chinese and Indian cohorts). In the Chinese cohort, significant evidence of association was noted at 3 SNPs: rs1015213 [A] in PCMTD1-ST18 (odds ratio [OR], 2.36; 95% confidence interval [CI], 1.36-4.11; P = 0.002), rs3816415 [A] in EPDR1 (OR, 1.49; 95% CI, 1.19-1.85; P < 0.001), and rs3739821 [G] in DPM2-FAM102A (OR, 1.40; 95% CI, 1.18-1.65; P < 0.001). Only PCMTD1-ST-18 was replicated modestly in the Indian population (P = 0.056). Meta-analysis showed significant evidence of association for PCMTD1-ST-18 (OR, 1.55; 95% CI, 1.18-2.04; P = 0.002) and DPM2-FAM102A (OR, 1.27; 95% CI, 1.12-1.45; P = 0.0002). CONCLUSIONS: In this study, 2 of 8 PACG-associated loci were associated significantly with PACS status, the earliest stage in the angle-closure glaucoma disease course. The association of these PACG loci with PACS status suggests that these loci may confer susceptibility to a narrow angle configuration.

Social, health and ocular factors associated with primary open-angle glaucoma amongst Chinese Singaporeans.

IMPORTANCE: There is limited literature on lifestyle and health factors related to primary open-angle glaucoma amongst Asians. BACKGROUND: This study evaluated the association of primary open-angle glaucoma with smoking, health and ocular factors amongst Chinese Singaporeans. DESIGN: Case-control study. PARTICIPANTS: The study used 711 primary open-angle glaucoma patients from a Singapore hospital and 2788 population-based controls. METHODS: Subjects underwent clinical examination and completed a questionnaire with details on family history of glaucoma, comorbidities, smoking and alcohol consumption. Glaucoma cases were subclassified as normal or high-tension glaucoma according to their untreated intraocular pressures. MAIN OUTCOME MEASURES: The association of various health and lifestyle factors, with normal-tension and high-tension glaucoma was evaluated. RESULTS: Using multiple logistic regression, primary open-angle glaucoma was associated with older age (odds ratio 1.12 per year older; 95% confidence interval 1.10-1.15; P < 0.001), family history of glaucoma (odds ratio 7.86; 95% confidence interval 4.48-13.79; P < 0.001), higher intraocular pressure (odds ratio 1.75 per 1 mmHg; 95% confidence interval 1.64-1.87; P < 0.001) and thinner central corneal thickness (odds ratio 1.01; 95% confidence interval 1.01-1.02; P < 0.001). Myopes were more likely to have primary open-angle glaucoma (P < 0.001). A current smoking habit was protective against normal-tension glaucoma (odds ratio 0.30; 95% confidence interval 0.10-0.92; P = 0.035). CONCLUSIONS AND RELEVANCE: Older age, family history of glaucoma, higher intraocular pressure, thinner central corneal thickness and myopia were significantly associated with primary open-angle glaucoma amongst Chinese Singaporeans.

Primary angle closure glaucoma (PACG) susceptibility gene PLEKHA7 encodes a novel Rac1/Cdc42 GAP that modulates cell migration and blood-aqueous barrier function.

PLEKHA7, a gene recently associated with primary angle closure glaucoma (PACG), encodes an apical junctional protein expressed in components of the blood aqueous barrier (BAB). We found that PLEKHA7 is down-regulated in lens epithelial cells and in iris tissue of PACG patients. PLEKHA7 expression also correlated with the C risk allele of the sentinel SNP rs11024102 with the risk allele carrier groups having significantly reduced PLEKHA7 levels compared to non-risk allele carriers. Silencing of PLEKHA7 in human immortalized non-pigmented ciliary epithelium (h-iNPCE) and primary trabecular meshwork cells, which are intimately linked to BAB and aqueous humor outflow respectively, affected actin cytoskeleton organization. PLEKHA7 specifically interacts with GTP-bound Rac1 and Cdc42, but not RhoA, and the activation status of the two small GTPases is linked to PLEKHA7 expression levels. PLEKHA7 stimulates Rac1 and Cdc42 GTP hydrolysis, without affecting nucleotide exchange, identifying PLEKHA7 as a novel Rac1/Cdc42 GAP. Consistent with the regulatory role of Rac1 and Cdc42 in maintaining the tight junction permeability, silencing of PLEKHA7 compromises the paracellular barrier between h-iNPCE cells. Thus, downregulation of PLEKHA7 in PACG may affect BAB integrity and aqueous humor outflow via its Rac1/Cdc42 GAP activity, thereby contributing to disease etiology.

New insights into the genetics of primary open-angle glaucoma based on meta-analyses of intraocular pressure and optic disc characteristics.

Primary open-angle glaucoma (POAG), the most common optic neuropathy, is a heritable disease. Siblings of POAG cases have a ten-fold increased risk of developing the disease. Intraocular pressure (IOP) and optic nerve head characteristics are used clinically to predict POAG risk. We conducted a genome-wide association meta-analysis of IOP and optic disc parameters and validated our findings in multiple sets of POAG cases and controls. Using imputation to the 1000 genomes (1000G) reference set, we identified 9 new genomic regions associated with vertical cup-disc ratio (VCDR) and 1 new region associated with IOP. Additionally, we found 5 novel loci for optic nerve cup area and 6 for disc area. Previously it was assumed that genetic variation influenced POAG either through IOP or via changes to the optic nerve head; here we present evidence that some genomic regions affect both IOP and the disc parameters. We characterized the effect of the novel loci through pathway analysis and found that pathways involved are not entirely distinct as assumed so far. Further, we identified a novel association between CDKN1A and POAG. Using a zebrafish model we show that six6b (associated with POAG and optic nerve head variation) alters the expression of cdkn1a. In summary, we have identified several novel genes influencing the major clinical risk predictors of POAG and showed that genetic variation in CDKN1A is important in POAG risk.

Genome-wide association study of Parkinson's disease in East Asians.

Genome-wide association studies (GWAS) on Parkinson's disease (PD) have mostly been done in Europeans and Japanese. No study has been done in Han Chinese, which make up nearly a fifth of the world population. We conducted the first Han Chinese GWAS analysing a total of 22,729 subjects (5,125 PD cases and 17,604 controls) from Singapore, Hong Kong, Malaysia, Korea, mainland China and Taiwan. We performed imputation, merging and logistic regression analyses of 2,402,394 SNPs passing quality control filters in 779 PD cases, 13,227 controls, adjusted for the first three principal components. 90 SNPs with association P < 10-4 were validated in 9 additional sample collections and the results were combined using fixed-effects inverse-variance meta-analysis. We observed strong associations reaching genome-wide significance at SNCA, LRRK2 and MCCC1, confirming their important roles in both European and Asian PD. We also identified significant (P < 0.05) associations at 5 loci (DLG2, SIPA1L2, STK39, VPS13C and RIT2), and observed the same direction of associations at 9 other loci including BST1 and PARK16. Allelic heterogeneity was observed at LRRK2 while European risk SNPs at 6 other loci including MAPT and GBA-SYT11 were non-polymorphic or very rare in our cohort. Overall, we replicate associations at SNCA, LRRK2, MCCC1 and 14 other European PD loci but did not identify Asian-specific loci with large effects (OR > 1.45) on PD risk. Our results also demonstrate some differences in the genetic contribution to PD between Europeans and Asians. Further pan-ethnic meta-analysis with European GWAS cohorts may unravel new PD loci.