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 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.

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.

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.

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.

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.

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.

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.

Genetic variants and cellular stressors associated with exfoliation syndrome modulate promoter activity of a lncRNA within the LOXL1 locus.

Exfoliation syndrome (XFS) is a common, age-related, systemic fibrillinopathy. It greatly increases risk of exfoliation glaucoma (XFG), a major worldwide cause of irreversible blindness. Coding variants in the lysyl oxidase-like 1 (LOXL1) gene are strongly associated with XFS in all studied populations, but a functional role for these variants has not been established. To identify additional candidate functional variants, we sequenced the entire LOXL1 genomic locus (∼40 kb) in 50 indigenous, black South African XFS cases and 50 matched controls. The variants with the strongest evidence of association were located in a well-defined 7-kb region bounded by the 3'-end of exon 1 and the adjacent region of intron 1 of LOXL1. We replicated this finding in US Caucasian (91 cases/1031 controls), German (771 cases/1365 controls) and Japanese (1484 cases/1188 controls) populations. The region of peak association lies upstream of LOXL1-AS1, a long non-coding RNA (lncRNA) encoded on the opposite strand of LOXL1. We show that this region contains a promoter and, importantly, that the strongly associated XFS risk alleles in the South African population are functional variants that significantly modulate the activity of this promoter. LOXL1-AS1 expression is also significantly altered in response to oxidative stress in human lens epithelial cells and in response to cyclic mechanical stress in human Schlemm's canal endothelial cells. Taken together, these findings support a functional role for the LOXL1-AS1 lncRNA in cellular stress response and suggest that dysregulation of its expression by genetic risk variants plays a key role in XFS pathogenesis.

Meta-analysis of Genome-Wide Association Studies Identifies Novel Loci Associated With Optic Disc Morphology.

Primary open-angle glaucoma is the most common optic neuropathy and an important cause of irreversible blindness worldwide. The optic nerve head or optic disc is divided in two parts: a central cup (without nerve fibers) surrounded by the neuroretinal rim (containing axons of the retinal ganglion cells). The International Glaucoma Genetics Consortium conducted a meta-analysis of genome-wide association studies consisting of 17,248 individuals of European ancestry and 6,841 individuals of Asian ancestry. The outcomes of the genome-wide association studies were disc area and cup area. These specific measurements describe optic nerve morphology in another way than the vertical cup-disc ratio, which is a clinically used measurement, and may shed light on new glaucoma mechanisms. We identified 10 new loci associated with disc area (CDC42BPA, F5, DIRC3, RARB, ABI3BP, DCAF4L2, ELP4, TMTC2, NR2F2, and HORMAD2) and another 10 new loci associated with cup area (DHRS3, TRIB2, EFEMP1, FLNB, FAM101, DDHD1, ASB7, KPNB1, BCAS3, and TRIOBP). The new genes participate in a number of pathways and future work is likely to identify more functions related to the pathogenesis of glaucoma.

CMPK1 and RBP3 are associated with corneal curvature in Asian populations.

Corneal curvature (CC) measures the steepness of the cornea and is an important parameter for clinically diseases such as astigmatism and myopia. Despite the high heritability of CC, only two associated genes have been discovered to date. We performed a three-stage genome-wide association study meta-analysis in 12 660 Asian individuals. Our Stage 1 was done in multiethnic cohorts comprising 7440 individuals, followed by a Stage 2 replication in 2473 Chinese and Stage 3 in 2747 Japanese. The SNP array genotype data were imputed up to the 1000 Genomes Project Phase 1 cosmopolitan panel. The SNP association with the radii of CC was investigated in the linear regression model with the adjustment of age, gender and principal components. In addition to the known genes, MTOR (also known as FRAP1) and PDGFRA, we discovered two novel genes associated with CC: CMPK1 (rs17103186, P = 3.3 × 10(-12)) and RBP3 (rs11204213 [Val884Met], P = 1.1 × 10(-13)). The missense RBP3 SNP, rs11204213, was also associated with axial length (AL) (P = 4.2 × 10(-6)) and had larger effects on both CC and AL compared with other SNPs. The index SNPs at the four indicated loci explained 1.9% of CC variance across the Stages 1 and 2 cohorts, while 33.8% of CC variance was explained by the genome-wide imputation data. We identified two novel genes influencing CC, which are related to either corneal shape or eye size. This study provides additional insights into genetic architecture of corneal shape.

Analysis of non-synonymous-coding variants of Parkinson's disease-related pathogenic and susceptibility genes in East Asian populations.

To evaluate the contribution of non-synonymous-coding variants of known familial and genome-wide association studies (GWAS)-linked genes for Parkinson's disease (PD) to PD risk in the East Asian population, we sequenced all the coding exons of 39 PD-related disease genes and evaluated the accumulation of rare non-synonymous-coding variants in 375 early-onset PD cases and 399 controls. We also genotyped 782 non-synonymous-coding variants of these genes in 710 late-onset PD cases and 9046 population controls. Significant enrichment of LRRK2 variants was observed in both early- and late-onset PD (odds ratio = 1.58; 95% confidence interval = 1.29-1.93; P = 8.05 × 10(-6)). Moderate enrichment was also observed in FGF20, MCCC1, GBA and ITGA8. Half of the rare variants anticipated to cause loss of function of these genes were present in healthy controls. Overall, non-synonymous-coding variants of known familial and GWAS-linked genes appear to make a limited contribution to PD risk, suggesting that clinical sequencing of these genes will provide limited information for risk prediction and molecular diagnosis.

Meta-analysis of genome-wide association studies in multiethnic Asians identifies two loci for age-related nuclear cataract.

Age-related cataract is a leading cause of blindness worldwide, especially in developing countries where access to cataract surgery remains limited. Previous linkage and candidate gene studies suggested genetic influences on age-related nuclear cataract but few genetic markers have been identified thus far. We conducted genome-wide association studies on 4569 Asians (including 2369 Malays and 2200 Indians), and replicated our analysis in 2481 Chinese from two independent cohorts (1768 Chinese in Singapore and 803 Chinese in Beijing). We confirmed two genome-wide significant loci for nuclear cataract in the combined meta-analysis of four cohorts (n = 7140). The first locus was at chromosome 3q25.31 in KCNAB1 (rs7615568, fixed-effect Pmeta = 2.30 × 10(-8); random-effect Pmeta = 1.08 × 10(-8)). The second locus was at chromosome 21 in the proximity of CRYAA (rs11911275, fixed-effect Pmeta = 2.77 × 10(-8); random-effect Pmeta = 1.98 × 10(-9)), a major protein component of eye lens. The findings were further supported by up-regulation and down-regulation of KCNAB1 and CRYAA in human lens capsule, respectively, as the severity of nuclear cataract increases. The results offer additional insights into the pathogenesis of nuclear cataract in Asians.

Linking a genome-wide association study signal to a LRRK2 coding variant in Parkinson's disease.

BACKGROUND: Genome-wide association studies have identified several loci associated with Parkinson's disease (PD). Whole-exome sequencing detects rare coding variants, but their links with PD genome-wide association study loci are unknown. Our objective was to investigate whether nonsynonymous variants in LRRK2 can explain associations at the PD-associated locus tagged by rs1994090. METHODS: We sequenced all coding exons of LRRK2 in 453 East Asian samples and evaluated linkage disequilibrium between each nonsynonymous variant and rs1994090. We then tested selected variants and haplotypes for association with PD in 13,581 East Asian samples. RESULTS: Of all the nonsynonymous variants, only p.Gly2385Arg was in moderate linkage disequilibrium with rs1994090 and was observed on haplotypes tagged by the rs1994090-C risk allele. Conditional analyses showed that associations at these 2 variants are not independent. CONCLUSIONS: LRRK2 p.Gly2385Arg can explain most if not all of the PD association at rs1994090 in East Asians, but other nonsynonymous variants are independent. © 2015 International Parkinson and Movement Disorder Society.

Transmembrane water-flux through SLC4A11: a route defective in genetic corneal diseases.

Three genetic corneal dystrophies [congenital hereditary endothelial dystrophy type 2 (CHED2), Harboyan syndrome and Fuchs endothelial corneal dystrophy] arise from mutations of the SLC4a11 gene, which cause blindness from fluid accumulation in the corneal stroma. Selective transmembrane water conductance controls cell size, renal fluid reabsorption and cell division. All known water-channelling proteins belong to the major intrinsic protein family, exemplified by aquaporins (AQPs). Here we identified SLC4A11, a member of the solute carrier family 4 of bicarbonate transporters, as an unexpected addition to known transmembrane water movement facilitators. The rate of osmotic-gradient driven cell-swelling was monitored in Xenopus laevis oocytes and HEK293 cells, expressing human AQP1, NIP5;1 (a water channel protein from plant), hCNT3 (a human nucleoside transporter) and human SLC4A11. hCNT3-expressing cells swelled no faster than control cells, whereas SLC4A11-mediated water permeation at a rate about half that of some AQP proteins. SLC4A11-mediated water movement was: (i) similar to some AQPs in rate; (ii) uncoupled from solute-flux; (iii) inhibited by stilbene disulfonates (classical SLC4 inhibitors); (iv) inactivated in one CHED2 mutant (R125H). Localization of AQP1 and SLC4A11 in human and murine corneal (apical and basolateral, respectively) suggests a cooperative role in mediating trans-endothelial water reabsorption. Slc4a11(-/-) mice manifest corneal oedema and distorted endothelial cells, consistent with loss of a water-flux. Observed water-flux through SLC4A11 extends the repertoire of known water movement pathways and call for a re-examination of explanations for water movement in human tissues.

Genome-wide association study identifies ZFHX1B as a susceptibility locus for severe myopia.

Severe myopia (defined as spherical equivalent < -6.0 D) is a predominant problem in Asian countries, resulting in substantial morbidity. We performed a meta-analysis of four genome-wide association studies (GWAS), all of East Asian descent totaling 1603 cases and 3427 controls. Two single nucleotide polymorphisms (SNPs) (rs13382811 from ZFHX1B [encoding for ZEB2] and rs6469937 from SNTB1) showed highly suggestive evidence of association with disease (P < 1 × 10(-7)) and were brought forward for replication analysis in a further 1241 severe myopia cases and 3559 controls from a further three independent sample collections. Significant evidence of replication was observed, and both SNP markers surpassed the formal threshold for genome-wide significance upon meta-analysis of both discovery and replication stages (P = 5.79 × 10(-10), per-allele odds ratio (OR) = 1.26 for rs13382811 and P = 2.01 × 10(-9), per-allele OR = 0.79 for rs6469937). The observation at SNTB1 is confirmatory of a very recent GWAS on severe myopia. Both genes were expressed in the human retina, sclera, as well as the retinal pigmented epithelium. In an experimental mouse model for myopia, we observed significant alterations to gene and protein expression in the retina and sclera of the unilateral induced myopic eyes for Zfhx1b and Sntb1. These new data advance our understanding of the molecular pathogenesis of severe myopia.

Aggregate Effects of Intraocular Pressure and Cup-to-Disc Ratio Genetic Variants on Glaucoma in a Multiethnic Asian Population.

PURPOSE: High intraocular pressure (IOP) and large vertical cup-to-disc ratio (VCDR) are important risk factors of glaucoma. Recent genome-wide association studies have discovered several genetic variants associated with IOP and VCDR. In this study, we examined the aggregate effects of these IOP-, VCDR-associated variants on glaucoma. DESIGN: Case-control genetic association study. PARTICIPANTS: A total of 6881 participants, including 194 glaucoma and 158 primary open-angle glaucoma (POAG) cases in the Singapore Epidemiology of Eye Diseases Study. METHODS: We first identified IOP and VCDR risk single nucleotide polymorphisms (SNPs) that were located in previously discovered IOP, VCDR genetic loci and showed strongest associations with IOP and VCDR in our study. We then constructed multi-locus IOP-, VCDR-specific genetic risk scores (GRSs) for each individual by summing the number of risk alleles for each SNP weighted by the respective effect estimates on glaucoma. Associations between tertiles of IOP- and VCDR-specific GRSs with glaucoma and POAG were determined using logistic regression analyses. Discriminating ability of the GRSs was determined by the area under receiver operating characteristic curve (AUC). MAIN OUTCOME MEASURES: Odds ratios on glaucoma. RESULTS: Participants in the top tertile of IOP-specific GRS were 2.00 (95% CI, 1.32-3.03, P = 1.1×10(-3)) and 2.50 times (95% CI, 1.54-4.02, P = 2.0×10(-4)) likely to have glaucoma and POAG, respectively, compared with those in the bottom. Participants in the top tertile of VCDR-specific GRS were 2.09 (95% CI, 1.43-3.07, P = 1.6×10(-4)) and 2.31 times (95% CI, 1.50-3.55, P = 1.4×10(-4)) likely to have glaucoma and POAG, respectively. Participants with both GRSs in the top tertile were 5.54 (95% CI, 2.57-11.93, P = 1.1×10(-5)) and 7.77 times (95% CI, 3.03-19.93, P = 2.0×10(-5)) likely to have glaucoma and POAG, respectively, compared with participants with both GRSs in bottom tertiles. The GRSs improved AUC for glaucoma modestly when added to traditional factors (AUC difference = 0.03, P = 0.06). CONCLUSIONS: Higher IOP-, VCDR-specific GRSs were associated with greater risk of glaucoma. Participants with both GRSs in the top tertiles had a 5.5-fold increased risk of glaucoma compared with those in the bottom tertiles. These findings may provide insights into the genetic pathogenesis of glaucoma.

A Genetic Variant in TGFBR3-CDC7 Is Associated with Visual Field Progression in Primary Open-Angle Glaucoma Patients from Singapore.

PURPOSE: To investigate whether known genetic loci for primary open-angle glaucoma (POAG) are associated with visual field (VF) progression in patients from a Singaporean Chinese population. DESIGN: Retrospective study. PARTICIPANTS: Patients with 5 or more reliable VF measurements who were being followed up at a Singapore hospital. METHODS: Visual field progression was identified using Progressor software version 3.7 (Medisoft, Leeds, United Kingdom) and defined by pointwise linear regression (PLR) criteria as follows: any 2 contiguous points in the same hemifield progressing (≤-1.00 dB/year for inner points and ≤-2.00 dB/year for edge points; P < 0.01). Single nucleotide polymorphisms (SNPs) and their proxies from 10 POAG-associated loci (CAV1-CAV2, CDKN2B-AS1, SIX1-SIX6, an intergenic region on chromosome 8q22, ABCA1, GAS7, AFAP1, GMDS, PMM2, and TGFBR3-CDC7) identified from genome-wide association studies were tested for association with VF progression using logistic regression with an additive genetic model adjusting for age, gender, average intraocular pressure (IOP), central corneal thickness (CCT), and baseline vertical cup-to-disc ratio (VCDR). MAIN OUTCOME MEASURE: Visual field progression. RESULTS: Of the 1334 patients included in the study, 469 subjects (35.1%) completed 5 or more reliable VF measurements (mean follow-up, 9.01 years; standard deviation, 5.00 years). The mean age of patients was 59.6 years (standard deviation, 9.0 years); 305 patients were men and all were Chinese. The average IOP in eyes fulfilling PLR progression was 16.5 mmHg versus 17.7 mmHg in those who did not (P = 0.52). Univariate analysis revealed that increased VCDR (P = 0.003), reduced CCT (P = 0.045), and reduced superior and inferior retinal nerve fiber layer thickness (P = 0.01, respectively) were associated with VF progression. No clinical or structural features were associated significantly with VF progression on multivariate analysis. The rs1192415 index SNP in TGFBR3-CDC7 (P = 0.002; odds ratio, 6.71 per risk allele) was the only SNP associated with VF progression. CONCLUSIONS: The presence of the index SNP rs1192415 (TGFBR3-CDC7) was associated with VF progression in POAG patients. These findings warrant further investigation in independent cohorts.

Genetic variants on chromosome 1q41 influence ocular axial length and high myopia.

As one of the leading causes of visual impairment and blindness, myopia poses a significant public health burden in Asia. The primary determinant of myopia is an elongated ocular axial length (AL). Here we report a meta-analysis of three genome-wide association studies on AL conducted in 1,860 Chinese adults, 929 Chinese children, and 2,155 Malay adults. We identified a genetic locus on chromosome 1q41 harboring the zinc-finger 11B pseudogene ZC3H11B showing genome-wide significant association with AL variation (rs4373767, ß = -0.16 mm per minor allele, P(meta) =2.69 × 10(-10)). The minor C allele of rs4373767 was also observed to significantly associate with decreased susceptibility to high myopia (per-allele odds ratio (OR) =0.75, 95% CI: 0.68-0.84, P(meta) =4.38 × 10(-7)) in 1,118 highly myopic cases and 5,433 controls. ZC3H11B and two neighboring genes SLC30A10 and LYPLAL1 were expressed in the human neural retina, retinal pigment epithelium, and sclera. In an experimental myopia mouse model, we observed significant alterations to gene and protein expression in the retina and sclera of the unilateral induced myopic eyes for the murine genes ZC3H11A, SLC30A10, and LYPLAL1. This supports the likely role of genetic variants at chromosome 1q41 in influencing AL variation and high myopia.