Association of SIX1-SIX6 polymorphisms with peripapillary retinal nerve fibre layer thickness in children.

PURPOSE: Association of SIX1-SIX6 variants with peripapillary retinal nerve fibre layer (p-RNFL) thickness had been reported in adults. This study aimed to investigate these associations in children, with further explorations by spatial, age and sex stratifications. METHODS: 2878 school children aged between 6 and 9 years were enrolled from the Hong Kong Children Eye Study. Three single-nucleotide polymorphisms (SNPs) at the SIX1-SIX6 locus were genotyped. The association of each SNP with p-RNFL thickness (including global and sectoral thickness) were evaluated using multiple linear regression. RESULTS: SNPs rs33912345 (p=7.7×10-4) and rs10483727 (p=0.0013) showed significant associations with temporal-inferior p-RNFL thickness. The C allele of rs33912345 was associated with a thinner temporal-inferior p-RNFL by an average of 2.44 µm, while rs10483727-T was associated with a thinner temporal-inferior p-RNFL by 2.32 µm. The association with temporal-inferior p-RNFL was the strongest in the 8-9 year-old group for rs33912345 (p=5.2×10-4) and rs10483727 (p=3.3×10-4). Both SNPs were significantly associated with temporal-inferior p-RNFL thickness in boys (p<0.0017), but not in girls (p>0.05). In contrast, rs12436579-C (ß=1.66; p=0.0059), but not rs33912345-C (ß=1.31; p=0.052) or rs10483727-T (ß=1.19; p=0.078), was nominally associated with a thicker nasal-inferior p-RNFL. CONCLUSIONS: Both rs33912345 and rs10483727 at SIX1-SIX6 were associated with p-RNFL thickness in children, especially at the temporal-inferior sector, with age-dependent and sex-specific effects. SNP rs12436579 was associated with nasal-inferior p-RNFL thickness. Our findings suggested a role of SIX1-SIX6 in RNFL variation during neural retina development in childhood.

Association of polymorphisms in ZFHX1B, KCNQ5 and GJD2 with myopia progression and polygenic risk prediction in children.

AIMS: To assess the association of single-nucleotide polymorphisms (SNPs) with myopia progression for polygenic risk prediction in children. METHODS: Six SNPs (ZC3H11B rs4373767, ZFHX1B rs13382811, KCNQ5 rs7744813, MET rs2073560, SNTB1 rs7839488 and GJD2 rs524952) were analysed in 1043 school children, who completed 3-year follow-up, using TaqMan genotyping assays. SNP associations with progression in spherical equivalent (SE) were analysed by logistic regression. Polygenic risk scores (PRS) were applied for computing the sum of the risk alleles of multiple SNPs corresponding to myopia progression, weighted by the effect sizes of corresponding SNPs. RESULTS: GJD2 rs524952 showed significant association with fast progression (OR=1.32, 95% CI 1.10 to 1.59; p=0.003) and KCNQ5 rs7744813 had nominal association (OR=1.32, 95% CI 1.04 to 1.67; p=0.02). In quantitative traits locus analysis, GJD2 rs524952 and KCNQ5 rs7744813 were associated with progression in SE (ß=-0.038 D/year, p=0.008 and ß=-0.042 D/year, p=0.02) and axial elongation (ß=0.016 mm/year, p=0.01 and ß=0.017 mm/year, p=0.027). ZFHX1B rs13382811 also showed nominal association with faster progression in SE (ß=-0.041 D/year, p=0.02). PRS analysis showed that children with the highest PRS defined by rs13382811, rs7744813 and rs524952 had a 2.26-fold of increased risk of fast myopia progression (p=4.61×10-5). PRS was also significantly associated with SE progression (R2=1.6%, p=3.15×10-5) and axial elongation (R2=1.2%, p=2.6×10-4). CONCLUSIONS: In this study, multi-tiered evidence suggested SNPs in ZFHX1B, KCNQ5 and GJD2 as risk factors for myopia progression in children. Additional attention and appropriate interventions should be given for myopic children with high-risk PRS as defined by GJD2 rs524952, KCNQ5 rs7744813 and ZFHX1B rs13382811.

Identification of TIE2 as a susceptibility gene for neovascular age-related macular degeneration and polypoidal choroidal vasculopathy.

PURPOSE: The endothelial and cell-specific angiopoietin-Tie pathway plays an important regulatory role in angiogenesis. In this study, we investigated the associations of the TIE2 (tyrosine kinase, endothelial, TEK) gene with neovascular age-related macular degeneration (nAMD) and polypoidal choroidal vasculopathy (PCV), using haplotype-tagging single-nucleotide polymorphisms (SNPs) analysis. METHODS: This study involved totally 2343 subjects, including a Hong Kong Chinese cohort (214 nAMD patients, 236 PCV patients and 433 control subjects), a Shantou Chinese cohort (189 nAMD patients, 187 PCV patients and 531 control subjects) and an Osaka Japanese cohort (192 nAMD patients, 204 PCV patients and 157 control subjects). Thirty haplotype-tagging SNPs in TIE2 were genotyped in the Hong Kong cohort using TaqMan technology. Two SNPs (rs625767 and rs2273717) showing association in the Hong Kong cohort were genotyped in the Shantou and Osaka cohorts. The SNP-disease association of individual and pooled cohorts were analysed. RESULTS: Two SNPs (rs625767 and rs2273717) showed suggestive association with both nAMD and PCV in the Hong Kong cohort. In the meta-analysis involving all the three cohorts, rs625767 showed significant associations with nAMD (p=0.01; OR=0.82, 95% CI 0.70 to 0.96; I2=0%), PCV (p=0.02; OR=0.83, 95% CI 0.71 to 0.97; I2=27%) and pooled nAMD and PCV (p=0.002; OR=0.82, 95% CI 0.72 to 0.93; I2=0%), with low inter-cohort heterogeneities. CONCLUSION: This study revealed TIE2 as a novel susceptibility gene for nAMD and PCV in Japanese and Chinese. Further studies in other populations are warranted to confirm its role.

Protective effects of an HTRA1 insertion-deletion variant against age-related macular degeneration in the Chinese populations.

Age-related macular degeneration (AMD) is a leading cause of visual impairment and irreversible blindness in most developed countries, affecting about 50 million elderly people worldwide. Retinal pigment epithelial (RPE) cell degeneration is the pathophysiological cause of AMD, leading to geographic atrophy and choroidal neovascularization. We and others have previously identified several polymorphisms on chromosome 10q26 (HTRA1 rs11200638 as well as LOC387715 rs10490924 and c.372_815del443ins54) associated with AMD. In this study, we confirmed the association of our previously identified HTRA1 insertion-deletion (indel) variant (c.34delCinsTCCT) in 195 exudative AMD patients and 390 controls from the Hong Kong Chinese cohort with additional 168 patients and 210 controls from the Chengdu Chinese cohort and followed by studying its biological functions in RPE cells. Genetic analysis verified the higher prevalence of c.34delCinsTCCT allele in control subjects (8.0%) than in AMD patients (1.9%; P=7.87 × 10-5, odds ratio=0.229). This protective effect was validated as the haplotype of the c.34delCinsTCCT allele existed independent of the risk haplotype (P=1.17 × 10-5). In vitro studies showed that recombinant HTRA1 c.34delCinsTCCT variant protein was more localized in the endoplasmic reticulum of RPE cells compared with the wild-type protein, and its secretion was delayed. Moreover, ARPE-19 cells expressing HTRA1 c.34delCinsTCCT variant had higher cell viability, lower cell apoptosis and were less responsive to anoikis, supporting its protective role. We revealed a protective AMD-associated HTRA1 variant in Chinese populations and the biological role of HTRA1 in RPE cell degeneration, indicating its involvement in AMD pathogenesis.