Genetic associations of central serous chorioretinopathy subtypes, neovascular age-related macular degeneration, and polypoidal choroidal vasculopathy

PURPOSE

To evaluate the genetic associations of different subtypes of central serous chorioretinopathy (CSCR), neovascular age-related macular degeneration (nAMD), and polypoidal choroidal vasculopathy (PCV).

DESIGN

A case-control genetic association study.

METHODS

This study enrolled 217 CSCR, 341 nAMD, 288 PCV patients, and 1380 controls. The CSCR patients were classified into those with focal or diffuse leakage, with or without pigment epithelial detachment (PED), and with or without macular neovascularization (MNV). Associations between 11 variants from 8 genes, ADAMTS9, ANGPT2, ARMS2, CFH, NR3C2, PGF, TNFRSF10A and VIPR2, and diseases/subtypes were analyzed by logistic regression analysis adjusted for age and sex, and inter-phenotype comparison by heterogeneity test.

RESULTS

The CFH rs800292-A conferred a protective effect for CSCR with MNV (OR=0.44, P = 0.002) and a risk effect for CSCR without MNV (OR=1.31, P = 0.023). CSCR patients carrying rs800292-G had a 3.23-fold of increased risk towards developing secondary MNV (P = 1.45 ×10-4). CFH rs3753394, rs800292 and rs1329428 showed similar effects among CSCR with MNV, nAMD and PCV, but opposite effects on CSCR without MNV. TNFRSF10A rs13278062-T was associated with overall CSCR but not with CSCR subtypes, nAMD or PCV. Moreover, CFH and ARMS2 SNPs showed heterogeneous effects in CSCR without MNV against CSCR with MNV, nAMD and PCV.

CONCLUSIONS

Genetic associations of CSCR with MNV resembled nAMD and PCV compared to CSCR without MNV, indicating differential genetic effects on neovascularization and choroidopathy. Further investigation of the functional roles of CFH, ARMS2, and TNFRSF10A in CSCR, nAMD and PCV should help elucidate the mechanisms of these maculopathies.

Association of Polymorphisms in ZFHX1B and PAX6 With Anisometropia in Chinese Children: The Hong Kong Children Eye Genetics Study

Purpose

To identify gene variants associated with anisometropia development in children.

Methods

This is a population-based, cross-sectional, and longitudinal genetic association study involving 1057 children aged 6 to 10 years with both baseline and 3-year follow-up data. Six single nucleotide polymorphisms (SNPs), ZC3H11B rs4373767, ZFHX1B rs13382811, KCNQ5 rs7744813, SNTB1 rs7839488, PAX6 rs644242, and GJD2 rs524952 were analyzed in all children. Anisometropia was defined by an interocular difference in SE of ≥1 diopter (D) (Aniso-SE) and an interocular difference in axial length (AL) of ≥0.3 mm (Aniso-AL), respectively. Genetic associations of individual SNPs and joint SNP effects were analyzed.

Results

ZFHX1B rs13382811 was associated nominally with Aniso-AL (odds ratio [OR], 1.66; P = 0.003) at baseline. At 3 years, rs13382811 was significantly associated with Aniso-AL (OR, 1.49; P = 0.001) and became nominally associated with Aniso-SE (OR, 1.40; P = 0.01). In addition, PAX6 rs644242 was significantly associated with Aniso-AL at 3 years (OR, 1.45; P = 0.002). At the 3-year follow-up, PAX6 rs644242 was associated significantly with Aniso-AL development (OR, 1.61; P = 0.0003) and nominally with Aniso-SE development (P = 0.03) in children who were not anisometropic at baseline, whereas ZFHX1B rs13382811 was associated nominally with Aniso-AL development (P = 0.02). An additive SNP analysis indicated children carrying the risk allele T of ZFHX1B rs13382811 and allele A of PAX6 rs644242 might have a 4.33- and 6.90-fold of increased risk of Aniso-SE and Aniso-AL development by 3 years, respectively.

Conclusions

This study identified two susceptible gene variants, ZFHX1B rs13382811 and PAX6 rs644242, for anisometropia development in Hong Kong Chinese children, implicating their role in imbalanced refractive change and axial elongation between both eyes.

Multi-Polymorphism Analysis Reveals Joint Effects in Males With Chronic Central Serous Chorioretinopathy

Purpose

Central serous chorioretinopathy (CSCR) is a leading cause of central vision impairment in the working-age population with male predilection. Knowledge about the genetic basis of CSCR and its male predilection remained limited. This study aimed to evaluate the association patterns of multiple gene variants in chronic CSCR (cCSCR) in Chinese patients.

Methods

This case-control genetic association study included 531 patients with cCSCR and 2383 controls from two independent Chinese cohorts. Nine single-nucleotide polymorphisms (SNPs) of six genes, namely CFH, NR3C2, GATA5, VIPR2, TNFRSF10A, and ARMS2, were genotyped in all subjects. The main outcome measures were the association of individual single-nucleotide polymorphism (SNP) with cCSCR, the sex-stratification effects of individual SNP, and joint effects of different SNPs on cCSCR.

Results

Association results in the two cohorts were consistent with low heterogeneities. In the combined analysis, SNPs CFH rs800292 (odds ratio [OR] = 1.25, P = 0.0020), CFH rs1329428 (OR = 1.23, P = 0.0037), and TNFRSF10A rs13278062 (OR = 1.43, P = 0.0014) were significantly associated with cCSCR. In stratification analysis by sex, 3 SNPs in CFH, rs3753394, rs800292, and rs1329428, were associated with cCSCR in male patients, but not in female patients. Joint analysis revealed that subjects homozygous for the risk alleles of CFH rs800292 and TNFRSF10A rs13278062 had over 4-fold of increased risk of cCSCR when compared with subjects homozygous for the non-risk alleles (OR = 4.06, P = 2.30 × 10-5).

Conclusions

This study revealed main and joint effects of SNPs in CFH and TNFRSF10A on cCSCR, and suggested CFH as a potential genetic factor underlying the male predilection of cCSCR. Further replication in other study populations is needed.

Association of WNT7B and RSPO1 with Axial Length in School Children

Purpose

To evaluate the association between single-nucleotide polymorphisms (SNPs) in the ZC3H11B, RSPO1, C3orf26, GJD2, ZNRF3, and WNT7B genes and myopia endophenotypes in children.

Methods

Seven SNPs identified in previous genome-wide association studies of axial length (AL) were genotyped in 2883 Southern Han Chinese children. Multiple linear regression analyses were conducted to evaluate the genotype association with AL, spherical equivalent (SE), corneal curvature (CC), and central corneal thickness (CCT).

Results

Two SNPs-namely, rs12144790 in RSPO1 (allele T, P = 0.0066, β = 0.062) and rs10453441 in WNT7B (allele A, P = 8.03 × 10-6, β = 0.103)-were significantly associated with AL. The association of rs4373767 in ZC3H11B (allele C, P = 0.030, β = -0.053) could not withstand the correction for multiple testing. WNT7B rs10453441 showed a strong association with CC (P = 1.17 × 10-14, β = 0.053) and with CCT (P = 0.0026, β = 2.65). None of the tested SNPs was significantly associated with SE. The C allele of SNP rs12321 in ZNRF3 was associated with CC (P = 0.0060, β = -0.018).

Conclusions

This study revealed that the RSPO1 SNP rs12144790 was associated with AL, whereas WNT7B rs10453441 was associated with AL, CC, and CCT in children. A novel association between ZNRF3 rs12321 and CC was discovered. Our data suggest that the RSPO1 and WNT7B genes might exert their effects on multiple aspects of eye growth during childhood. Potential differences in the genetic profiles of AL between children and adults should be explored in larger cohorts.

Association of the CAV1-CAV2 locus with normal-tension glaucoma in Chinese and Japanese

BACKGROUND

The CAV1-CAV2 locus has been associated with primary open-angle glaucoma (POAG) and intraocular pressure. However, its association with normal-tension glaucoma (NTG) was inconclusive. Therefore, we evaluated this association in Chinese and Japanese.

METHODS

Two single-nucleotide polymorphisms (SNPs, rs4236601 and rs1052990) from previous genome-wide association studies of POAG were genotyped in a total of 2220 study subjects: a Hong Kong Chinese cohort of 537 NTG patients and 490 controls, a Shantou Chinese cohort of 102 NTG and 731 controls and an Osaka Japanese cohort of 153 NTG and 207 controls. Subgroup analysis by gender was conducted. Outcomes from different cohorts were combined using meta-analysis.

RESULTS

SNP rs4236601 was significantly associated with NTG in the two Chinese cohorts (P_meta = .0019, OR = 4.55, I² = 0). In contrast, rs4236601 was monomorphic in the Osaka cohort. The association of rs1052990 was insignificant in a meta-analysis combining Chinese and Japanese cohorts (P_meta = .81, OR = 1.05; I² = 64%), and the OR tended towards opposite directions between Chinese (OR = 1.26) and Japanese (OR = 0.69). Gender-specific effects of the SNPs were not statistically significant in the logistic regression or Breslow-day tests of ORs (P > .05), although rs4236601 was significant in males (P = .0068; OR = 10.30) but not in females (P = .14; OR = 2.65) in the meta-analysis of Chinese subjects.

CONCLUSIONS

In this study, we confirmed the association of rs4236601 at the CAV1-CAV2 locus with NTG in Chinese. SNP rs4236601 is monomorphic, and rs1052990 tends towards a different direction in the Japanese cohort. Further studies are warranted to verify the ethnic difference and gender-specific effects of this locus.

Evaluation of the association of C5 with neovascular age-related macular degeneration and polypoidal choroidal vasculopathy

Background

Neovascular age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV) are sight-threatening maculopathies with both environmental and genetic risk factors. We have previously shown relative risks posed by genes of the complement pathways to neovascular AMD and PCV.

Methods

In this study, we investigated the haplotype-tagging single nucleotide polymorphisms (SNPs) in the complement component 5 (C5) gene in 708 unrelated Chinese individuals: 200 neovascular AMD patients, 233 PCV patients and 275 controls. Six tagging SNPs in C5 were genotyped. Univariate single SNP association analysis, haplotype-based association analysis and gene-gene interaction analysis between C5 and other AMD-associated genes were performed.

Results

The results revealed none of the six tagging SNPs of the C5 gene had a significant association with neovascular AMD or PCV (P > 0.05). We also found insignificant haplotype-based association, and no significant SNP-SNP interaction between C5 and other genes (including C2-CFB-RDBP-SKIV2L, SERPING1, CETP, ABCG1, PGF, ANGPT2, CFH and HTRA1) for neovascular AMD and PCV.

Conclusions

This study showed no statistical significance in the genetic association of C5 with neovascular AMD or PCV in a Hong Kong Chinese population. Further studies in large samples from different populations are warranted to elucidate the role of C5 in the genetic susceptibility of AMD and PCV.

Identification and characterization of a novel promoter variant in placental growth factor for neovascular age-related macular degeneration

PURPOSE

Intronic variants in the placental growth factor (PGF) gene have been associated with neovascular age-related macular degeneration (AMD). This study is to discover and characterize rare variants in the PGF gene for neovascular AMD.

METHODS

The promoter region, coding sequences and splicing regions of the PGF gene were sequenced in a Hong Kong southern Chinese cohort of 235 neovascular AMD patients and 435 controls. A detected 18 base-pair deletion variant in the promoter region of PGF was analyzed in a Shantou southern Chinese cohort of 189 neovascular AMD patients and 846 controls. The transcription activity of this disease-associated promoter variant was determined in human ARPE-19 cells by promoter-luciferase analysis.

RESULTS

A novel 18-base-pair deletion mutation in the promoter region of PGF was identified in 3 (1.28%) patients and 1 (0.23%) control subject (OR = 5.61; 95% CI 0.58-54.26) in the Hong Kong cohort, and in 2 (1.06%) patients and 2 (0.24%) controls (OR = 4.51; 95% CI: 0.63-32.25) in the Shantou cohort. In the combined southern Chinese sample, this deletion had a significant association with neovascular AMD (P = 0.026; OR = 5.08, 95% CI: 1.21-21.36). The 18-base-pair deletion was predicted to alter the transcription factor binding sites in the PGF promoter, and higher luciferase expression was detected in ARPE-19 cells transfected with the deletion variant plasmid than those transfected with wild type plasmid (P = 0.0002).

CONCLUSIONS

This study identified a rare, functional promoter variant in the PGF gene that increases PGF transcription activity and confers a 5-fold risk to neovascular AMD.

Association of the ZC3H11B, ZFHX1B and SNTB1 genes with myopia of different severities

OBJECTIVE

To investigate the associations of single-nucleotide polymorphisms (SNPs) in the ZC3H11B, ZFHX1B, VIPR2, SNTB1 and MIPEP genes with severities of myopia in Chinese populations.

METHODS

Based on previous myopia genome-wide association studies, five SNPs (ZC3H11B rs4373767, ZFHX1B rs13382811, VIPR2 rs2730260, SNTB1 rs7839488 and MIPEP rs9318086) were selected for genotyping in a Chinese cohort of 2079 subjects: 252 extreme myopia, 277 high myopia, 393 moderate myopia, 366 mild myopia and 791 non-myopic controls. Genotyping was performed by TaqMan assays. Allelic frequencies of the SNPs were compared with myopia severities and ophthalmic biometric measurements.

RESULTS

The risk allele T of ZC3H11B SNP rs4373767 was significantly associated with high myopia (OR=1.39, p=0.007) and extreme myopia (OR=1.34, p=0.013) when compared with controls, whereas ZFHX1B rs13382811 (allele T, OR=1.33, p=0.018) and SNTB1 rs7839488 (allele G, OR=1.71, p=8.44E-05) were significantly associated with extreme myopia only. In contrast, there was no significant association of these SNPs with moderate or mild myopia. When compared with mild myopia, subjects carrying T allele of rs4373767 had a risk of progressing to high myopia (spherical equivalent ≤-6 dioptres) (OR=1.29, p=0.017). Similarly, the T allele of rs13382811 also imposed a significant risk to high myopia (OR=1.36, p=0.007). In quantitative traits analysis, SNPs rs4373767, rs13382811 and rs7839488 were correlated with axial length and refractive errors.

CONCLUSIONS

We confirmed ZC3H11B as a susceptibility gene for high and extreme myopia, and ZFHX1B and SNTB for extreme myopia in Chinese populations. Instead of myopia onset, these three genes were more likely to impose risks of progressing to high and extreme myopia.

Genome-wide analysis identified 17 new loci influencing intraocular pressure in Chinese population

Intraocular pressure (IOP) is a major risk factor for glaucoma. Genetic determinants of intraocular pressure can provide critical insights into the genetic architecture of glaucoma and, as a result, open new avenues for therapeutic intervention. We performed a genome-wide association study and replication analysis of 8,552 Chinese participants. In the genome-wide association study, we identified 51 loci that surpassed the significance of P<9×10^-7, and we formally replicated these loci. A combined discovery and replication meta-analysis identified 21 genome-wide loci that surpassed the genome-wide significance of P<5×10^-8, including 4 previously reported loci: rs145063132 (7p21.2, ETV1/DGKB), rs548030386 (7q31.2, ST7 near CAV1/CAV2), rs7047871 (9p24.2, GLIS3), and rs2472494 (9q31.1, ABCA1/SLC44A1). Of the 17 newly identified loci, five were reported to have ocular related phenotypes: PTCH2 (rs7525308 in 1p34.1), LRIF1/DRAM2 (rs1282146 in 1p13.3), COLEC11 (rs201143466 in 2p25.3), SPTBN1 (rs4514918 in 2p16.2), and CRK (rs11078446 in 17p13.3). The genetic loci identified in this study not only increase our understanding of the genes involved in intraocular pressure but also provide important genetic markers to improve future genetic screening and drug discovery for intraocular pressure disorders.

Association of coding and UTR variants in the known regions with wet age-related macular degeneration in Han Chinese population

Age-related macular degeneration (AMD) is the leading cause worldwide of severe visual impairment among people older than 55 years of age. This study aimed to investigate the genetic association between coding and untranslated region (UTR) variants in previously reported loci and exudative age-related macular degeneration (wet AMD) in a Han Chinese population. Using our previously published whole exome sequencing dataset of 349 wet AMD patients and 1253 controls, we searched for associations between coding and UTR variants of the 72 genes located within the 47 reported wet AMD loci regions. From these, 25 variants in 18 of the 72 genes with P < 10 × 10^-3 were selected for the first replication of Sequenom mass-array genotyping in 885 wet AMD subjects and 562 controls. Next, four SNPs were selected for further validation by SNaPshot genotyping in a third Chinese cohort with 456 wet AMD subjects and 211 controls. As a result, we identified two new potential coding and UTR variant SNPs (rs189132250 in BBX located in 3q12.1 and rs144351944 in FILIP1L located in 3q12.1) that showed weak associations with wet AMD in the Han Chinese population. These findings provide new information regarding the coding and UTR variants of the known wet AMD loci in the studied Chinese cohort.

Analysis of multiple genetic loci reveals MPDZ-NF1B rs1324183 as a putative genetic marker for keratoconus

OBJECTIVE

To investigate the associations between 16 single-nucleotide polymorphisms (SNPs) in 14 genetic loci and keratoconus in an independent Chinese cohort.

METHODS

This cross-sectional, case-control association study included a Chinese cohort of 133 patients with keratoconus and 371 control subjects. In a recent meta-analysis study, we identified association of 16 SNPs in 14 gene loci with keratoconus. In this study, we genotyped these 16 SNPs in all the patients and controls and analysed their association with keratoconus, its clinical severities and progression profiles. We also analysed the genotype-phenotype correlation between individual SNPs and steep keratometry, flat keratometry (Kf), average keratometry (Avg K) and best-fit sphere diameter (BFS) of the anterior and posterior corneal surface.

RESULTS

Among the 16 selected SNPs, rs1324183 in the MPDZ-NF1B locus showed a significant association with keratoconus (OR=2.22; 95% CI 1.42 to 3.45, p=4.30×10^-4), especially severe keratoconus (OR=5.10, 95% CI 1.63 to 15.93, p=0.005). The rs1324183 A allele was positively associated with anterior Kf (p=0.008), anterior Avg K (p=0.017), posterior Kf (p=0.01) and negatively associated with apex pachymetry (p=0.007) and anterior BFS (p=0.023) in keratoconus. The other 15 SNPs had no significant association with keratoconus or genotype-phenotype correlations.

CONCLUSIONS

This study confirmed the association of SNP rs1324183 in MPDZ-NF1B with keratoconus and revealed the association of this SNP with keratoconus severity and corneal parameters. It is thus a putative genetic marker for monitoring the progression of keratoconus to a severe form and facilitating early intervention.

Association of the PAX6 gene with extreme myopia rather than lower grade myopias

Aims

To investigate the association of the paired box gene 6 (PAX6) with different severities of myopia.

Methods

A total of four haplotype-tagging single-nucleotide polymorphisms (SNPs; rs2071754, rs3026354, rs3026390 and rs628224) and two previously reported SNPs (rs644242 and rs662702) in the PAX6 gene were analysed in a Hong Kong Chinese cohort of 1288 myopia subjects (including 252 extreme myopia, 277 high myopia, 393 moderate myopia and 366 mild myopia) and 791 no myopia controls. Allelic association analyses were performed for individual SNPs in different subgroups of myopia and in combined myopia, followed by a meta-analysis of our current data with reported data on PAX6 in myopia.

Results

The association of tagging SNPs rs2071754 and rs644242 with extreme myopia could not withstand multiple correction (rs2071754: OR=1.25, P value=0.031; rs644242: OR=1.33, P value=0.032). In the meta-analysis, rs644242 showed an enhanced, significant association with extreme myopia (OR=1.27, 95% CI 1.10 to 1.46, P value=0.001; I2=0%). In contrast, there was no significant association between the PAX6SNPs and high, moderate or mild myopia. No linear correlation was found between the PAX6SNPs and axial length.

Conclusion

This study provides additional evidence suggesting that the PAX6 SNP rs644242 is associated with extreme myopia but not lower grade myopia. Thus, PAX6 may be implicated in the development or progression into severe myopia. Further longitudinal studies are warranted.

Genetic Association of the PARL-ABCC5-HTR3D-HTR3C Locus With Primary Angle-Closure Glaucoma in Chinese

Purpose

This study evaluates the associations of haplotype-tagging single nucleotide polymorphisms (SNPs) in the PARL-ABCC5-HTR3D-HTR3C region with primary angle closure glaucoma (PACG), with a view to identify the responsible SNP in this region.

Methods

Thirty SNPs from the PARL-ABCC5-HTR3D-HTR3C region were genotyped in a Hong Kong Chinese cohort of 422 PACG patients and 400 control subjects, using TaqMan SNP genotyping assays. Single marker and haplotype-based association analyses were performed.

Results

Two synonymous ABCC5 SNPs, namely rs939336 (p.Cys594=; P = 0.013; odds ratio [OR] = 1.46; 95% confidence interval [CI], 1.08 to 1.97) and rs1132776 (p.Ala395=; P = 0.009; OR = 1.47; 95% CI: 1.10 to 1.95), were associated with PACG. Mild associations were detected for ABCC5 rs9838667 (P = 0.024) and HTR3D rs12493550 (P = 0.035). Conditional analysis revealed that no SNPs remained significant after adjusting for other SNPs, suggesting none of these tagging SNPs is fully responsible for the association in this region. In subgroup analysis, ABCC5 SNPs rs939336, rs1132776, and rs983667 and HTR3D rs12493550 were associated only with the chronic form of PACG. However, these associations could not withstand the correction for multiple testing.

Conclusions

These findings enrich the allelic spectrum of ABCC5 in PACG. We identified no tagging SNP responsible for the association of the whole region. Further deep sequencing analysis of this region should be warranted to uncover whether there is still disease associated variant in this region.

Identification of ANGPT2 as a New Gene for Neovascular Age-Related Macular Degeneration and Polypoidal Choroidal Vasculopathy in the Chinese and Japanese Populations

Purpose

We determine the angiopoietin 2 (ANGPT2) gene as a new susceptibility gene for neovascular age-related macular degeneration (nAMD) and polypoidal choroidal vasculopathy (PCV).

Methods

A total of 34 haplotype-tagging single-nucleotide polymorphisms (SNPs) were first genotyped in an exploratory Hong Kong Chinese cohort. Suggestive SNPs were replicated in a Shantou Chinese cohort and an Osaka Japanese cohort, with a total of 2343 subjects. The SNP rs800292 in the complement factor H (CFH) gene was genotyped in all the subjects. Genetic association and gene-gene interaction were analyzed.

Results

In the Hong Kong cohort, four SNPs in ANGPT2 (rs13255574, rs4455855, rs13269021, and rs11775442) were nominally associated with nAMD and PCV. The four ANGPT2 SNPs showed the same trends of association in the Shantou and Osaka cohorts. Combining the data from the 3 study cohorts revealed that SNPs rs4455855 and rs13269021 achieved study-wise significance (P < 0.0016), conferring an approximately 1.3-fold of increased risk for nAMD and PCV. Interaction analysis revealed the CFH SNP rs800292 has a highly significant interaction with the ANGPT2 SNP rs13269021 in nAMD and PCV in the combined analysis. Subsequent stratification analysis confirmed the interaction.

Conclusions

This study reveals ANGPT2 as a new susceptibility gene for nAMD and PCV, and it may affect disease susceptibility in association with CFH. Thus, this report provides new insights into the genetic architecture of nAMD and PCV.

HTRA1 promoter variant differentiates polypoidal choroidal vasculopathy from exudative age-related macular degeneration

Exudative age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV) share similar abnormal choroidal vasculature, but responses to treatments are different. In this study, we sequenced the whole HTRA1 gene and its promoter by direct sequencing in a Hong Kong Chinese PCV cohort. We identified rs11200638, c.34delCinsTCCT, c.59C>T, rs1049331 and rs2293870 significantly associated with PCV. Notably, rs2672598 was significantly associated with exudative AMD (p = 1.31 × 10(-4)) than PCV (p = 0.11). Logistic regression indicated that rs2672598 (p = 2.27 × 10(-3)) remained significant after adjusting for rs11200638 in exudative AMD. Moreover, the rs11200638-rs2672598 joint genotype AA-CC conferred higher risk to exudative AMD (43.11 folds) than PCV (3.68 folds). Promoter analysis showed that rs2672598 C-allele showed higher luciferase expression than wildtype T-allele (p = 0.026), independent of rs11200638 genotype (p = 0.621). Coherently, vitreous humor HTRA1 expression with rs2672598 CC genotype was significantly higher than that with TT genotype by 2.56 folds (p = 0.02). Furthermore, rs2672598 C-allele was predicted to alter the transcription factor binding sites, but not rs11200638 A-allele. Our results revealed that HTRA1 rs2672598 is more significantly associated with exudative AMD than PCV in ARMS2/HTRA1 region, and it is responsible for elevated HTRA1 transcriptional activity and HTRA1 protein expression.

Ethnic specific association of the CAV1/CAV2 locus with primary open-angle glaucoma

A single-nucleotide polymorphism (SNP) rs4236601 at the CAV1/CAV2 locus is associated with primary open-angle glaucoma (POAG). Rs4236601 is common in Caucasians but rare in East Asians. Here we conducted a haplotype-tagging SNP analysis followed by replication in a total of 848 POAG cases and 1574 controls drawn from 3 cities in China and 1 city in Japan. Two SNPs, rs4236601 (odds ratio [OR] = 6.25; P = 0.0086) and a tagging-SNP rs3801994 (OR = 1.32; P = 0.042), were associated with POAG in the Hong Kong Chinese cohort after age and gender adjustments. Rs4236601 was associated with POAG also in Shantou (OR = 6.09; P = 0.0037) and Beijing (OR = 3.92; P = 0.030) cohorts after age and gender adjustment, with a pooled-OR of 5.26 (P = 9.0 × 10(-6)) in Chinese; but it is non-polymorphic in the Osaka cohort. SNP rs3801994 showed a similar trend of effect in the Shantou and Beijing cohorts, with a pooled-OR of 1.23 (P = 0.022) and 1.20 (P = 0.063) in Chinese, prior to and after age and gender adjustment, respectively; but it showed a reverse effect in the Osaka cohort (OR = 0.58; P = 0.033) after the adjustments. We have thus confirmed the association of rs4236601 with POAG in different Chinese cohorts. Also, we found a common SNP rs3801994 of diverse associations with POAG between Chinese and Japanese.

A missense variant in FGD6 confers increased risk of polypoidal choroidal vasculopathy

Polypoidal choroidal vasculopathy (PCV), a subtype of 'wet' age-related macular degeneration (AMD), constitutes up to 55% of cases of wet AMD in Asian patients. In contrast to the choroidal neovascularization (CNV) subtype, the genetic risk factors for PCV are relatively unknown. Exome sequencing analysis of a Han Chinese cohort followed by replication in four independent cohorts identified a rare c.986A>G (p.Lys329Arg) variant in the FGD6 gene as significantly associated with PCV (P = 2.19 × 10(-16), odds ratio (OR) = 2.12) but not with CNV (P = 0.26, OR = 1.13). The intracellular localization of FGD6-Arg329 is distinct from that of FGD6-Lys329. In vitro, FGD6 could regulate proangiogenic activity, and oxidized phospholipids increased expression of FGD6. FGD6-Arg329 promoted more abnormal vessel development in the mouse retina than FGD6-Lys329. Collectively, our data suggest that oxidized phospholipids and FGD6-Arg329 might act synergistically to increase susceptibility to PCV.

Identification of PGF as a New Gene for Neovascular Age-Related Macular Degeneration in a Chinese Population

PURPOSE

To determine the associations of the VEGFA, VEGFB, and placental growth factor (PGF) genes with neovascular age-related macular degeneration (nAMD) and polypoidal choroidal vasculopathy (PCV).

METHODS

Seven single-nucleotide polymorphisms (SNPs) in VEGFA, three SNPs in VEGFB, and five SNPs in PGF were genotyped in 1722 unrelated Chinese participants, including a Hong Kong cohort of 214 nAMD patients, 236 PCV patients, and 365 controls, and an independent Shantou cohort of 189 nAMD patients, 187 PCV patients, and 531 controls, using TaqMan genotyping assays.

RESULTS

Placental growth factor SNPs rs2268615 (G allele, P = 0.0047; odds ratio [OR] = 1.54, 95% confidence interval [CI], 1.14-2.08) and rs2268614 (G allele, P = 0.015; OR = 1.46, 95% CI, 1.07-1.97) were associated with nAMD. A significant omnibus haplotype association with nAMD was detected for a two-SNP window containing rs2268615 and rs2268614, with a haplotype G-G conferring a 1.54-fold increased risk (P = 0.0042) in the Hong Kong cohort and a 1.42-fold risk (P = 0.012) in the Shantou cohort. Pooling of the Hong Kong and Shantou data enhanced the association of nAMD with rs2268615 (P = 0.0022; OR = 1.38, 95% CI, 1.12-1.69; I2 = 0%), rs2268614 (P = 0.0067; OR = 1.33, 95% CI, 1.08-1.63; I2 = 0%), and the G-G haplotype (P = 0.0013; OR = 1.46, 95% CI, 1.16-1.84; I2 = 0%). In contrast, the PGF SNPs and haplotype were not associated with PCV. Our results also revealed no association of SNPs in VEGFA and VEGFB with nAMD or PCV.

CONCLUSION

Placental growth factor is a susceptibility gene for nAMD in a Chinese population, providing new evidence to support a biological role of PGF in choroidal neovascularization.

SPP2 Mutations Cause Autosomal Dominant Retinitis Pigmentosa

Retinitis pigmentosa (RP) shows progressive loss of photoreceptors involved with heterogeneous genetic background. Here, by exome sequencing and linkage analysis on a Chinese family with autosomal dominant RP, we identified a putative pathogenic variant, p.Gly97Arg, in the gene SPP2, of which expression was detected in multiple tissues including retina. The p.Gly97Arg was absent in 800 ethnically matched chromosomes and 1400 in-house exome dataset, and was located in the first of the two highly conserved disulfide bonded loop of secreted phosphoprotein 2 (Spp-24) encoded by SPP2. Overexpression of p.Gly97Arg and another signal peptide mutation, p.Gly29Asp, caused cellular retention of both endogenous wild type and exogenous mutants in vitro, and primarily affected rod photoreceptors in zebrafish mimicking cardinal feature of RP. Taken together, our data indicate that the two mutations of SPP2 have dominant negative effects and cellular accumulation of Spp-24 might be particularly toxic to photoreceptors and/or retinal pigment epithelium. SPP2 has a new role in retinal degeneration.

Ethnic differences in the association of SERPING1 with age-related macular degeneration and polypoidal choroidal vasculopathy

Neovascular age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV) are leading causes of irreversible blindness in developed countries. In this study, we investigated the association of single nucleotide polymorphisms (SNPs) in the serpin peptidase inhibitor, clade G, member 1 (SERPING1) gene with neovascular AMD and PCV. Two haplotype-tagging SNPs, rs1005510 and rs11603020, of SERPING1 were genotyped in 708 unrelated Chinese individuals: 200 neovascular AMD, 233 PCV and 275 controls. A meta-analysis was also performed for all reported associations of SERPING1 SNPs with AMD and PCV. None of the tagging SNPs had a significant association with neovascular AMD or PCV (P > 0.05) in our study cohort. The meta-analyses showed that the most-studied SNP rs2511989 was not significantly associated with all forms of AMD, neovascular AMD, or PCV in East Asians (P = 0.98, 0.93 and 0.30, respectively) but was associated with AMD in Caucasians (P = 0.04 for all AMD and 0.004 for neovascular AMD). Therefore, the results of our study and meta-analysis suggest that SERPING1 is not a major genetic component of AMD or PCV in East Asians but is a genetic risk factor for AMD in Caucasians, providing evidence for an ethnic diversity in the genetic etiology of AMD.

FPR1 interacts with CFH, HTRA1 and smoking in exudative age-related macular degeneration and polypoidal choroidal vasculopathy

PURPOSE

To determine the genetic association of an inflammation-related gene, formyl peptide receptor 1 (FPR1), in exudative age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV).

METHODS

The coding region of FPR1 gene was sequenced in 554 unrelated Chinese individuals: 155 exudative AMD patients, 179 PCV patients, and 220 controls. Interactions and combined effects of FPR1 with complement factor H (CFH), high temperature requirement factor A1 (HTRA1), and smoking were also investigated.

RESULTS

A total of 28 polymorphisms in FPR1 were identified. Single nucleotide polymorphisms (SNP) rs78488639 increased the risk to exudative AMD (P=0.043) and PCV (P=0.016), whereas SNP rs867229 decreased the risk to exudative AMD (P=0.0026), but not PCV. Homozygous G allele of rs1042229 was associated with exudative AMD (P=0.0394, odds ratio (OR)=2.27, 95% confident interval: 1.08-4.74), but not with PCV. Exudative AMD, but not PCV, was associated with the heterozygous genotypes of rs2070746 (P=0.019, OR=0.57) and rs867229 (P=0.0082, OR=0.54). Significantly, interactions were identified among FPR1 rs78488639, CFH rs800292, and HTRA1 rs11200638 in both exudative AMD and PCV. Combined heterozygous risk alleles of CFH rs800292 GA and FPR1 rs78488639 CA were posed to PCV (P=2.22 × 10(-4), OR=10.47), but not exudative AMD. Furthermore, FPR1 rs78488639 CA combining with HTRA1 rs11200638 and smoking was also predisposed risks to exudative AMD and PCV.

CONCLUSION

FPR1 is associated with exudative AMD and PCV in a Hong Kong Chinese cohort. FPR1 rs78488639 interacted with CFH rs800292, HTRA1 rs11200638, and smoking, enhancing risk to exudative AMD and PCV.

Genes in the high-density lipoprotein metabolic pathway in age-related macular degeneration and polypoidal choroidal vasculopathy

PURPOSE

To investigate the associations of genetic variants in the high-density lipoprotein (HDL) metabolism pathway with neovascular age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV).

DESIGN

Cross-sectional, case-control association study.

PARTICIPANTS

A Chinese case-control group of 200 neovascular AMD patients, 233 PCV patients, and 275 control subjects.

METHODS

Eight single nucleotide polymorphisms (SNPs) from 6 genes of the HDL metabolism pathway and 2 known AMD-associated SNPs, rs800292 (from complement factor H [CFH]) and rs11200638 (from HtrA serine peptidase 1 [HTRA1]), were genotyped in all study subjects using the TaqMan genotyping technology (Applied Biosystems, Foster City, CA).

MAIN OUTCOME MEASURES

Allele and genotypic frequencies of selected SNPs.

RESULTS

The SNP rs3764261 in the cholesteryl ester transfer protein (CETP) gene was associated significantly with neovascular AMD (P = 1.82×10(-4); odds ratio [OR], 1.89) and PCV (P = 4.04×10(-4); OR, 1.80). The associations remained significant after adjusting for the CFH SNP rs800292 and the HTRA1 SNP rs11200638. A significant interaction between the CETP SNP rs3764261 and the CFH SNP rs800292 existed in both neovascular AMD and PCV, the rs800292 G allele conferring a significantly increased risk of the diseases only in individuals carrying the risk allele T of rs3764261. A borderline association was detected between the ATP-binding cassette, subfamily G, member 1 (ABCG1) gene SNP rs57137919 and PCV (P = 0.03).

CONCLUSIONS

Our results showed that CETP is a susceptibility gene for neovascular AMD and PCV and that ABCG1 a putative gene for PCV. CETP exerts a modifying effect on CFH in the genetic risk. Our data suggest a link of the HDL metabolism pathway with neovascular AMD and PCV.

PRPF4 mutations cause autosomal dominant retinitis pigmentosa

Retinitis pigmentosa (RP), a disease characterized by progressive loss of photoreceptors, exhibits significant genetic heterogeneity. Several genes associated with U4/U6-U5 triple small nuclear ribonucleoprotein (tri-snRNP) complex of the spliceosome have been implicated in autosomal dominant RP (adRP). HPrp4, encoded by PRPF4, regulates the stability of U4/U6 di-snRNP, which is essential for continuous splicing. Here, we identified two heterozygous variants in PRPF4, including c.-114_-97del in a simplex RP patient and c.C944T (p.Pro315Leu), which co-segregates with disease phenotype in a family with adRP. Both variants were absent in 400 unrelated controls. The c.-114_-97del, predicted to affect two transcription factor binding sites, was shown to down-regulate the promoter activity of PRPF4 by a luciferase assay, and was associated with a significant reduction of PRPF4 expression in the blood cells of the patient. In fibroblasts from an affected individual with the p.Pro315Leu variant, the expression levels of several tri-snRNP components, including PRPF4 itself, were up-regulated, with altered expression pattern of SC35, a spliceosome marker. The same alterations were also observed in cells over expressing hPrp4(Pro315Leu), suggesting that they arose as a compensatory response to a compromised splicing mechanism caused by hPrp4 dysfunction. Further, over expression of hPrp4(Pro315Leu), but not hPrp4(WT), triggered systemic deformities in wild-type zebrafish embryos with the retina primarily affected, and dramatically augmented death rates in morphant embryos, in which orthologous zebrafish prpf4 gene was silenced. We conclude that mutations of PRPF4 cause RP via haploinsufficiency and dominant-negative effects, and establish PRPF4 as a new U4/U6-U5 snRNP component associated with adRP.

Association of CFH and SERPING1 polymorphisms with anterior uveitis

AIMS

To investigate the association of the complement factor H (CFH) and complement component 1 inhibitor (SERPING1) genes with anterior uveitis (AU).

METHODS

A total of 406 subjects (98 patients with AU and 308 controls) were recruited for this study. Two CFH polymorphisms (rs3753394 and rs1065489) and two SERPING1 polymorphisms (rs1005511 and rs3824988) were genotyped using TaqMan genotyping assays. Analyses were stratified for gender and human leukocyte antigen (HLA)-B27 status. Correlations of the genotypes with multiple clinical features were also evaluated.

RESULTS

No significant association was found between any of the four polymorphisms and AU after multiple testing corrections. However, stratified analyses showed that there were significant increases in the frequencies of T allele and TT homozygosity for CFH-rs1065489 in female patients compared with that of controls (pcorr=0.004 and pcorr=0.012 respectively). In addition, CFH-rs1065489 was also associated with AU in patients who were HLA-B27 positive. No significant association with AU was found for the other three single nucleotide polymorphisms (SNPs), even stratified by gender or HLA-B27 status. Genotype-phenotype analyses found that CFH-rs1065489 TT genotype was associated with higher uveitis recurrence frequency. No correlation was found between CFH-rs1065489 and other clinical features.

CONCLUSIONS

This study revealed an association of CFH-rs1065489 with AU as well as uveitis recurrence frequency. The influence on AU could be gender specific and dependent on HLA-B27 status. Our results also suggested that SERPING1 does not play a significant role in the development of AU.

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.

Contribution of SNRNP200 sequence variations to retinitis pigmentosa

PURPOSE

Mutations in the SNRNP200 gene have been reported to cause autosomal dominant retinitis pigmentosa (adRP). In this study, we evaluate the mutation profile of SNRNP200 in a cohort of southern Chinese RP patients.

METHODS

Twenty adRP patients from 11 families and 165 index patients with non-syndromic RP with mixed inheritance patterns were screened for mutations in the mutation hotspots of SNRNP200. These included exons 12-16, 22-32, and 38-45, which covered the two helicase ATP-binding domains in DEAD-box and two sec-63 domains. The targeted regions were amplified by polymerase chain reaction and analyzed by direct DNA sequencing, followed by in silico analyses.

RESULTS

Totally 26 variants were identified, 18 of which were novel. Three non-synonymous variants (p.C502R, p.R1779H and p.I698V) were found exclusively in patients. Two of them, p.C502R and p.R1779H, were each identified in one simplex RP patient, whereas p.I698V occurred in one patient with unknown inheritance pattern. All three residues are highly conserved in SNRNP200 orthologs. Nevertheless, only p.C502R and p.R1779H were predicted to affect protein function by in silico analyses, suggesting these two variants are likely to be disease-causing mutations. Notably, all mutations previously identified in other study populations were not detected in this study.

CONCLUSIONS

Our results reveal a distinct mutation profile of the SNRNP200 gene in a southern Chinese cohort of RP patients. The identification of two novel candidate mutations in two respective patients affirmed that SNRNP200 contributes to a proportion of overall RP.

A genome-wide meta-analysis identifies two novel loci associated with high myopia in the Han Chinese population

High myopia, highly prevalent in the Chinese population, is a leading cause of visual impairment worldwide. Genetic factors play a critical role in the development of this visual disorder. Genome-wide association studies in recent years have revealed several chromosomal regions that contribute to its progression. To identify additional genetic variants for high myopia susceptibility, we used a genome-wide meta-analysis to examine the associations between the disease and 286 031 single-nucleotide polymorphisms (SNPs) in a combined cohort of 665 cases and 960 controls. The most significant SNPs (n = 61) were genotyped in a replication cohort (850 cases and 1197 controls), and 14 SNPs were further tested through genotyping in two additional validation cohorts (combined 1278 cases and 2486 controls). As a result of this analysis, four SNPs reached genome-wide significance (P < 2.0 × 10(-7)). The most significantly associated SNP, rs2730260 [overall P = 8.95 × 10(-14); odds ratio (95% CI) =1.33 (1.23-1.44)], is located in the VIPR2 gene, which is located in the MYP4 locus. The other three SNPs (rs7839488, rs4395927 and rs4455882) in the same linkage disequilibrium block are located in the SNTB1 gene, with -P values ranging from 1.13 × 10(-8) to 2.13 × 10(-11). The VIPR2 and SNTB1 genes are expressed in the retina and the retinal pigment epithelium and have been previously reported to have potential functions for the pathogenesis of myopia. Our results suggest that variants of the VIPR2 and SNTB1 genes increase susceptibility to high myopia in Han Chinese.

Associations of the C2-CFB-RDBP-SKIV2L locus with age-related macular degeneration and polypoidal choroidal vasculopathy

PURPOSE

To investigate the associations of the C2-CFB-RDBP-SKIV2L region with neovascular age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV).

DESIGN

Cross-sectional, case-control association study.

PARTICIPANTS

A Chinese case-control group of 200 neovascular AMD patients, 233 PCV patients, and 275 control subjects.

METHODS

An association analysis was performed of the C2-CFB-RDBP-SKIV2L locus with both neovascular AMD and PCV in a Chinese population using 19 haplotype-tagging single nucleotide polymorphisms (SNPs) and 6 previously reported SNPs across the C2-CFB-RDBP-SKIV2L region. All SNPs were genotyped using the TaqMan genotyping technology (TaqMan; Applied Biosystems [ABI], Foster City, CA).

MAIN OUTCOME MEASURES

Allele and haplotype frequencies of the SNPs in the C2-CFB-RDBP-SKIV2L region.

RESULTS

The SKIV2L SNPs rs429608 and rs453821 were significantly associated with neovascular AMD (P = 7.39 × 10(-5); odds ratio [OR], 0.22; 95% confidence interval [CI], 0.10-0.50; and P = 0.001; OR, 0.38; 95% CI, 0.21-0.70, respectively), whereas borderline associations were detected for C2 rs547154 (P = 0.002) and RDBP rs760070 (P = 0.003). Conditional haplotype analysis revealed that SKIV2L rs429608 could account fully for the global haplotype association identified in this region. The association of SKIV2L rs429608 with neovascular AMD remained significant after adjusting for CFH rs800292 and HTRA1 rs11200638. No individual SNP or haplotype was associated significantly with PCV.

CONCLUSIONS

In this concurrent investigation of the associations of the entire C2-CFB-RDBP-SKIV2L region with neovascular AMD and PCV, the results suggested that SKIV2L is a likely causal gene for neovascular AMD, conferring a significant protective effect independent of CFH and HTRA1. These data do not support a significant role of this region in PCV, suggesting different molecular mechanisms between neovascular AMD and PCV.

Differentiation of exudative age-related macular degeneration and polypoidal choroidal vasculopathy in the ARMS2/HTRA1 locus

PURPOSE

differentiate the associations of exudative age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV) with the ARMS2/HTRA1 locus.

METHODS

The entire ARMS2 sequence was sequenced and HTRA1 rs11200638 genotyped in 568 unrelated Chinese individuals: 156 exudative AMD patients, 164 PCV patients, and 248 controls. A meta-analysis was performed to examine the effects of rs10490924 and rs11200638 at the ARMS2/HTRA1 locus in PCV.

RESULTS

In total, 31 polymorphisms in ARMS2 were identified. Significant associations with both exudative AMD and PCV were observed in 11 of them and HTRA1 rs11200638, with different genotypic distributions between exudative AMD and PCV (P < 0.001). After adjusting for rs11200638, ARMS2 rs10490924 remained significantly associated with exudative AMD (P = 0.011), but not with PCV (P = 0.077). Meta-analysis showed consistent allelic associations of rs10490924 and rs11200638 with PCV in different study populations.

CONCLUSIONS

There is a strong and consistent association of the ARMS2/HTRA1 locus with both exudative AMD and PCV, suggesting the two disorders share, at least partially, similar molecular mechanisms. Different effect sizes indicate the existence of additional genetic and environmental factors affecting them to different extents.

Common variants near CAV1 and CAV2 are associated with primary open-angle glaucoma

We conducted a genome-wide association study for primary open-angle glaucoma (POAG) in 1,263 affected individuals (cases) and 34,877 controls from Iceland. We identified a common sequence variant at 7q31 (rs4236601[A], odds ratio (OR) = 1.36, P = 5.0 × 10⁻¹⁰). We then replicated the association in sample sets of 2,175 POAG cases and 2,064 controls from Sweden, the UK and Australia (combined OR = 1.18, P = 0.0015) and in 299 POAG cases and 580 unaffected controls from Hong Kong and Shantou, China (combined OR = 5.42, P = 0.0021). The risk variant identified here is located close to CAV1 and CAV2, both of which are expressed in the trabecular meshwork and retinal ganglion cells that are involved in the pathogenesis of POAG.

Association of polymorphisms of tumor necrosis factor and tumor protein p53 with primary open-angle glaucoma

PURPOSE

To evaluate the variants of 10 genes for association with primary open-angle glaucoma (POAG) in a Chinese population.

METHODS

A total of 405 unrelated patients with POAG (255 high-tension glaucoma [HTG], 100 normal-tension glaucoma [NTG], and 50 juvenile-onset open-angle glaucoma [JOAG]) and 201 control subjects were recruited. Seventeen variants in 10 genes with reported association with POAG were genotyped for analysis of allele and haplotype frequencies between cases and control subjects. These genes included CDH1 (cadherin 1, type 1, E-cadherin), CDKN1A (cyclin-dependent kinase inhibitor 1A), CYP1B1 (cytochrome P450, family 1, subfamily B, polypeptide 1), GSTM1 (glutathione S-transferase mu 1), GSTT1 (glutathione S-transferase theta 1), MTHFR (5,10-methylenetetrahydrofolate reductase), NOS3 (nitric oxide synthase 3), OPA1 (optic atrophy 1), TNF (tumor necrosis factor), and TP53 (tumor protein p53).

RESULTS

One SNP (-308G>A; rs1800629) in TNF demonstrated a significant association with HTG (P = 0.012). The allele G frequency was higher in HTG patients than in control subjects (94.6% vs. 90.3%; OR = 1.89). One haplotype consisting of rs1799724 and rs1800629 was significantly associated with HTG (P = 0.015, corrected P = 0.045). One SNP (R72P; rs1042522) in TP53 was significantly associated with NTG (P = 0.018). The allele G frequency was higher in NTG patients than in control subjects (56.1% vs. 45.8%; OR = 1.52). The significance of these associations survived the Bonferroni correction (corrected P < 0.024). Other gene variants were not significantly associated with HTG (P > 0.063) or NTG (P > 0.13). None of the studied variants was significantly associated with JOAG (P > 0.17).

CONCLUSIONS

The findings suggest that variants in TNF and TP53 are risk factors for POAG, whereas variants in other studied genes are not major risk factors for POAG, at least in the Chinese population.

Differential pattern of RP1 mutations in retinitis pigmentosa

PURPOSE

Retinitis pigmentosa 1 (RP1) is a major gene responsible for both autosomal dominant and autosomal recessive retinitis pigmentosa (RP). We have previously identified three disease-causing mutations out of 174 RP patients. In this study, we investigated a new cohort of Chinese RP patients to further evaluate the contribution of RP1 mutations to cause RP.

METHODS

A group of 55 nonsyndromic RP patients, the majority of them isolated cases or without information on family history, were screened for mutations in the entire coding sequences of RP1, using direct DNA sequencing. All detected variants were genotyped in 190 controls, while the three putative mutations were additionally genotyped in 362 controls subjects. Web-based programs, including PolyPhen, Sorting Intolerant from Tolerant (SIFT), Prediction of Pathological Mutations (PMUT), Single Amino Acid Polymorphism Disease-Association Predictor (SAP), ScanProsite, and ClustalW2, were used to predict the potential functional and structural impacts of the missense variants on RP1.

RESULTS

A total of 14 sequence changes were identified. Among them, five were novel and found only in the RP patients. Two missense variants (p.K1370E and p.R1652L), which are conserved in primates, were predicted to have functional and structural impacts on the RP1 protein. The other three variants (c.787+34T>C, p.I408L and p.L2015L) were considered benign.

CONCLUSIONS

If these two novel missense variants are in fact pathogenic, then RP1 mutations account for approximately 2.18% (5/229) of RP cases in our Chinese cohort; this is similar to other ethnic groups. However, a relatively higher frequency of missense mutations found in the Chinese patients may suggest an ethnic diversity in the RP1 mutation patterns.

Compound heterozygosity of two novel truncation mutations in RP1 causing autosomal recessive retinitis pigmentosa

Purpose. To evaluate the phenotypic effects of two novel frameshift mutations in the RP1 gene in a Chinese pedigree of autosomal recessive retinitis pigmentosa (ARRP). Methods. Family members of a proband with ARRP were screened for RP1, RHO, NR2E3, and NRL mutations by direct sequencing. Detected RP1 mutations were genotyped in 225 control subjects. Since one family member with the RP1 deletion mutation in exon 2 was found to have age-related macular degeneration (AMD) but not RP, exons 2 and 3 of RP1 were screened in 120 patients with exudative AMD. Major AMD-associated SNPs in the HTRA1 and CFH genes were also investigated. Results. Two novel frameshift mutations in RP1, c.5_6delGT and c.4941_4942insT, were identified in the pedigree. They were absent in 225 control subjects. Family members who were compound heterozygous for the nonsense mutations had early-onset and severe RP, whereas those with only one mutation did not have RP. No mutations in RHO, NR2E3, and NRL were identified in the pedigree. Subject I:2 with AMD carried both at-risk genotypes at HTRA1 rs11200638 and CFH rs800292. No mutation in RP1 exons 2 and 3 was identified in 120 AMD patients. Conclusions. This report is the first to associate ARRP with compound heterozygous nonsense mutations in RP1. Identification of the nonsense-mediated mRNA decay (NMD)-sensitive mutation c.5_6delGT provided further genetic evidence that haploinsufficiency of RP1 is not responsible for RP. The authors propose four classes of truncation mutations in the RP1 gene with different effects on the etiology of RP.

HTRA1 variants in exudative age-related macular degeneration and interactions with smoking and CFH

PURPOSE

Mapping the genes for age-related macular degeneration (AMD) had not been successful until recent genome-wide association studies revealed Tyr402His in CFH and rs11200638 in HTRA1 as AMD-related genetic variants. This study was conducted to identify other critical factors in HTRA1 that are associated with exudative AMD.

METHODS

The promoter, splice regions, and coding exons of HTRA1 were sequenced in 163 patients with exudative AMD and 183 sex- and age-matched control subjects. Also documented were the CFH genotype and smoking status.

RESULTS

Four significant SNPs were found in the promoter and the first exon of HTRA1: rs11200638 (-625G>A), rs2672598 (-487T>C), rs1049331 (102C>T, Ala34Ala), and rs2293870 (108G>T, Gly36Gly) with respective P = 1.7 x 10(-14), 3.0 x 10(-10), 3.7 x 10(-12), and 3.7 x 10(-12). Among them, rs11200638 is the most significant associated SNP with a high odds ratio (OR) of 7.6 (95% CI: 3.94-14.51). One risk haplotype block across the promoter and exon 1, ACCTT, significantly predisposes to AMD (P = 6.68 x 10(-14)). In both models, significant independent additive effects were identified with smoking and rs800292 (184G>A, Val62Ile) of CFH. Smoking and rs11200638 (HTRA1) combined caused a 15.7-fold increased risk, whereas combined rs800292 and rs11200638 caused a 23.3-fold increased risk. An extremely high population attributable risk (PAR) of 78% was also found.

CONCLUSIONS

A high impact of the additive effect of CFH and HTRA1 in the development of exudative AMD was shown. The HTRA1-smoking additive effect found in this study further suggests the importance of this environmental risk factor in AMD.

Multiple gene polymorphisms in the complement factor h gene are associated with exudative age-related macular degeneration in chinese

PURPOSE

Variants in the complement factor H (CFH) gene have been shown to be strongly associated with age-related macular degeneration (AMD). In this study, sequence alterations in CFH were investigated in 163 Chinese patients with exudative AMD and 155 unrelated Chinese control subjects.

METHODS

All the 22 CFH exons, intron-exon boundaries, and promoter sequences were screened by polymerase chain reaction and DNA sequencing.

RESULTS

Fifty-eight sequence changes, 42 of them novel, were identified. Six SNPs with an allele frequency >30% were significantly associated with exudative AMD. SNP rs3753396 was novel; the rest had been reported: rs3753394, rs551397, rs800292, rs2274700, and rs1329428. Two haplotype blocks were constructed. The TG haplotype for rs551397 and rs800292 was the major haplotype that conferred a significantly increased susceptibility to exudative AMD (P(corr) = 0.0001, OR = 1.91, 95% CI = 1.36-2.68).

CONCLUSIONS

The findings support prior evidence that the CFH gene is one of the AMD-associated genes. There is a different distribution pattern of CFH variants in the Chinese compared with other populations. Individual SNP and haplotype analyses revealed that the ancient alleles at the 5' end of CFH contribute to an increased susceptibility to exudative AMD.

A genome-wide scan maps a novel high myopia locus to 5p15

PURPOSE

This study was conducted to investigate the genetic component of three Chinese pedigrees originating from Hong Kong with autosomal dominant high myopia.

METHODS

A whole-genome scan was performed by using microsatellite markers spanning the whole genome with an average spacing of 10 cM. Regions containing markers that yielded LOD scores >1.0 were further analyzed by fine mapping with additional microsatellite markers. Fine-scale mapping of the linkage region was performed by genotyping a set of gene-based SNP markers on a cohort of 94 high myopia cases and 94 control subjects.

RESULTS

Two-point LOD scores >1 were observed at markers D5S630, D5S416, D7S510, D11S908, and D17S944. Additional microsatellite markers flanking D5S630 revealed a maximum two-point LOD score of 4.81 at D5S2505 at theta = 0.00. Haplotype analysis narrowed the linkage region to 5p15.33-p15.2 with a 17.45-cM interval. The coding sequences of five genes located within this region, IRX2, IRX1, POLS, CCT5, and CTNND2, were screened. No segregation of polymorphism with high myopia was found. Genotyping of 41 SNPs within this region in a Chinese cohort of 94 high myopia cases and 94 control subjects showed that the allele and genotype distributions of one SNP, rs370010, was different between cases and controls (genotype P = 0.01176, allele P = 0.00271 and trend P = 0.00375), but such association did not remain significant after false discovery rate (FDR) correction. This SNP is located within a hypothetical gene LOC442129.

CONCLUSIONS

A novel autosomal dominant high myopia locus was mapped on chromosome 5p15.33-p15.2 with an interval of 17.45 cM.

Association of CTLA-4 and IL-13 gene polymorphisms with Graves' disease and ophthalmopathy in Chinese children

PURPOSE

The frequency of childhood Graves' disease (GD) in Hong Kong Chinese is among the highest in the world but childhood Graves' ophthalmopathy (GO) appears to have milder clinical severity than does the adult disease. This study was conducted to investigate CTLA-4 and IL-13 polymorphisms in Chinese pediatric patients with GD and GO.

METHODS

Recruited for the study were 177 childhood patients with GD (age range, 2-16 years) and 151 unrelated control subjects (age range, 4-16 years) for genotype analysis of IL-13 single-nucleotide polymorphisms (SNPs) (-1112C/T and 2044G/A), CTLA-4 SNPs (-318C/T, 49A/G, and CT60A/G), and the repeat length of (AT)n in the 3' untranslated region (UTR) of CTLA-4.

RESULTS

The patients with GD revealed higher frequencies of CTLA-4 49 GG genotype and G alleles than did the control subjects (P = 0.005 and P = 0.03, respectively). The CT60 GG genotype and G alleles were more prevalent in GD (P = 0.07 and P = 0.02, respectively). The CTLA-4 SNPs (-318C/T, 49A/G, and CT60A/G) were in the same haplotype block, and the CGG haplotype was associated with GD (P = 0.0071) but not GO. The shortest allele of (AT)n was protective against GD (P = 8.4 x 10(-6)). The IL-13 SNPs did not affect GD or GO risk. IL-13 -1112C/T was associated with IgE elevation (P = 0.044) and 2044G/A with proptosis (P = 0.02), but these associations became insignificant after Bonferroni correction (P = 0.22 and 0.10, respectively).

CONCLUSIONS

Three SNPs and the AT repeat length in CTLA-4 conferred susceptibility to childhood GD, whereas IL-13 polymorphisms did not. No association was found between CTLA-4 and IL-13 with GO.

Evaluation of LOXL1 polymorphisms in primary open-angle glaucoma in southern and northern Chinese

PURPOSE

The lysyl oxidase-like protein 1 (LOXL1) gene is strongly associated with exfoliation glaucoma, which is very rare in the Chinese population. The implicated LOXL1 polymorphisms have not been associated with primary open-angle glaucoma (POAG). In this study, we investigated three of the LOXL1 polymorphisms in POAG in a southern Chinese population of Hong Kong and northern Chinese from Beijing.

METHODS

The Hong Kong group included 293 POAG patients and 250 controls, and the Beijing group included 169 POAG patients and 197 controls. LOXL1 single nucleotide polymorphisms (SNPs), rs1048661, rs3825942, and rs2165241, were genotyped by direct DNA sequencing. Individual association was analyzed using the chi(2) test, and haplotype-based association analysis was performed in WHAP.

RESULTS

Each of the candidate SNPs was not statistically associated with POAG in either group (p>0.017, Bonferroni correction). Haplotype-based association analysis had identified a significant omnibus association (Omnibus chi(2)=18.16, p=0.00115) between these SNPs and POAG in the Hong Kong group. A minor haplotype (T-G-T) showed significant statistical association with POAG. It presented in 2.1% of cases and 0.4% of controls, conferring a 5.24 fold of increased risk to the disease (95% CI: 1.17-23.54, P(perm)=0.00108). However, this haplotype was absent in the Beijing group.

CONCLUSIONS

Individual LOXL1 SNPs, rs1048661, rs3825942, and rs2165241, were not associated with POAG in the Chinese population. However, a minor haplotype T-G-T was found to be associated with the disorder in the southern Chinese. The low frequencies of the at-risk alleles at rs1048661 and rs2165241 may be one of the factors that led to the low prevalence of exfoliation syndrome in the general populations of the Chinese.

Genotype phenotype analysis of Bietti's crystalline dystrophy in patients with CYP4V2 mutations

PURPOSE

To evaluate the genotypic and phenotypic correlations of Bietti's crystalline dystrophy (BCD) in patients with the CYP4V2 gene by mutation screening and clinical and electrophysiological assessment.

METHODS

Eighteen Chinese patients in 13 families with BCD were recruited for full ophthalmic examinations, optical coherence tomography (OCT), and visual electrophysiological tests, including electrooculography (EOG), full-field electroretinography (ERG), and multifocal electroretinography (mfERG). Peripheral venous blood was obtained from all index patients and their family members for genomic DNA extraction and CYP4V2 sequence screening by direct sequencing.

RESULTS

All 18 patients with BCD had mutations in the CYP4V2 gene: five were novel (Y219H, W244X, D324V, P396L, and R400C) and four had been reported. A common mutation occurred at the splice site IVS6-8del17bp/insGC of 12 patients, four being homozygous. OCT showed the presence of intraretinal crystals in all patients. Patients with more severe thinning of the retina had worse visual acuity, and there was moderate correlation between the OCT central foveal thickness and visual acuity (Spearman rho = 0.46, P = 0.005). Patients with splice site mutations (i.e., homozygous IVS6-8del17bp/insGC or compound heterozygous IVS6-8del17bp/insGC and IVS8-2A>G) had lower EOG Arden index (P = 0.014) and were more likely to have a nonrecordable scotopic full-field ERG (P = 0.003) and nonrecordable 30-Hz flicker ERG (P = 0.043).

CONCLUSIONS

BCD patients with homozygous IVS6-8del17bp/insGC or compound heterozygous IVS6-8del17bp/insGC and IVS8-2A>G mutations appeared to have more severe disease phenotype based on electrophysiological testing. The level of visual loss in BCD is related to the severity of retinal thinning.

A novel missense RP1 mutation in retinitis pigmentosa

AIMS

More than 20 mutations associated with retinitis pigmentosa (RP) have been identified in the retinitis pigmentosa 1 (RP1) gene, all of them leading to the production of a truncated protein without 50-70% of the C-terminal of the RP1 protein. RP1 was recently found to be a microtubule-associated protein (MAP) and responsible for the organisation of the photoreceptor outer segment. The N-terminal doublecortin (DCX) domain of RP1 is essential for its function. But how the C-terminal of the protein affects its function is still not known. This study aims to get a better understanding of the RP1 gene by mutation screening on RP patients.

METHODS

Peripheral blood was taken from 72 RP patients. Together with 101 RP patients and 190 control subjects previously reported, mutation screening was performed by polymerase chain reaction (PCR) and direct sequencing. Statistical analysis was performed using SPSS.

RESULTS

Two novel missense sequence changes, D984G and C727W, and one novel variant, 6492T>G, at the 3' untranslated region were found. They were not found in 190 control subjects. D984G causes RP. It creates two possible N-myristoylation sites according to PROSITE. C727W does not segregate with RP in the family. It abolishes an N-myristoylation site. R872H, a previously reported polymorphism, was predominantly present in control subjects (P=0.001).

CONCLUSIONS

Our results suggest that disruption of the C-terminal of RP1 may be associated with the development of RP, and the possible involvement of the RP1 polypeptide downstream of its DCX domain in normal RP1 function.

A Genome-wide Scan Maps a Novel Juvenile-Onset Primary Open-Angle Glaucoma Locus to 15q

PURPOSE

To map the disease-associated locus of a family with autosomal dominant juvenile-onset primary open-angle glaucoma (JOAG).

METHODS

A complete ophthalmic examination was conducted, and genomic DNA was obtained from 25 members of a Chinese family, of which eight were confirmed as having JOAG. Myocilin (MYOC), optineurin (OPTN), and WD repeat-domain 36 (WDR36) were screened for sequence alterations, by PCR and direct sequencing. Subsequently, a genome-wide scan was performed (Prism Linkage Mapping Set MD-10; Applied Biosystems, Inc., Foster City, CA). Two-point and multipoint linkage analyses were performed with the MLINK, ILINK, and LINKMAP programs. For fine mapping, additional markers flanking the most promising region on 15q were analyzed. The significance of the lod score was tested with simulation analyses by using FASTLINK. Haplotypes were constructed with Simwalk2. Three candidate genes, NR2E3, SMAD6, and CLN6, located within the critical region, were screened for mutations.

RESULTS

MYOC, OPTN, and WDR36 mutations were excluded in all family members. A maximum two-point lod score of 3.31 at theta = 0.0 was obtained for the marker D15S125. Four adjacent markers, rs2030040, rs169169963, D15S153, and D15S131, gave two-point lod scores of 2.41, 2.90, 3.02, and 2.68, respectively, at theta = 0.0. Haplotype analysis and recombination mapping further confined this region to 15q22-q24 within a genetic distance of 16.6 Mb flanked by D15S1036 and rs922693. No mutations were found in the coding exons and splicing junctions of NR2E3, SMAD6, and CLN6.

CONCLUSIONS

The results provide evidence for the mapping of a novel locus for JOAG at 15q22-q24. A further search for the disease-causing gene in this new JOAG locus is in progress.

HTRA1 promoter polymorphism in wet age-related macular degeneration

Age-related macular degeneration (AMD), the most common cause of irreversible vision loss in individuals aged older than 50 years, is classified as either wet (neovascular) or dry (nonneovascular). Inherited variation in the complement factor H gene is a major risk factor for drusen in dry AMD. Here we report that a single-nucleotide polymorphism in the promoter region of HTRA1, a serine protease gene on chromosome 10q26, is a major genetic risk factor for wet AMD. A whole-genome association mapping strategy was applied to a Chinese population, yielding a P value of <10(-11). Individuals with the risk-associated genotype were estimated to have a likelihood of developing wet AMD 10 times that of individuals with the wild-type genotype.

Novel Myocilin Mutation in a Chinese Family With Juvenile-Onset Open-Angle Glaucoma

OBJECTIVE

To search for the genetic cause of juvenile-onset open-angle glaucoma (JOAG) in a Chinese family.

METHODS

In a 3-generation glaucoma family affected with JOAG or ocular hypertension, we screened myocilin (MYOC) and optineurin (OPTN) for mutations and investigated apolipoprotein E (APOE) polymorphisms in 6 family members, 2 of them patients with JOAG, 2 patients with ocular hypertension, and 2 patients who were asymptomatic. Normal controls included 200 unrelated Chinese subjects. The COS-7 cell line was transfected with expression vectors encoding wild-type or mutated MYOC complementary DNA. Cellular and secreted MYOC proteins were characterized by Western blotting.

RESULTS

One missense MYOC mutation, 734G>A: Cys245Tyr, was identified. It occurred in all 4 family members afflicted with JOAG or ocular hypertension but not in asymptomatic family members. No OPTN variations were observed. APOE polymorphism frequencies were similar to those for controls. The Cys245Tyr MYOC mutation cosegregated with the disorder within the family. It was absent in the 200 control subjects. The Cys245Tyr mutant MYOC protein formed homomultimeric complexes that migrated at molecular weights larger than their wild-type counterparts. These mutant complexes remained sequestered intracellularly in COS-7 cells.

CONCLUSIONS

The Cys245Tyr MYOC mutation was the genetic cause of JOAG in this Chinese family. This mutation may alter covalent bonds that formed between MYOC cysteines. Clinical Relevance Genetic tests of MYOC mutations may be beneficial to predict new cases of the disease in families with JOAG.

Genetic markers for retinitis pigmentosa

OBJECTIVE

To review recent advances in the molecular genetics of retinitis pigmentosa with emphasis on the development of genetic markers that aids diagnosis and prognosis.

DATA SOURCES AND EXTRACTION

Literature search of MEDLINE from 1988 to 2005 using the following key words: 'retinitis pigmentosa', 'rhodopsin', 'RP1', 'RPGR', and 'genetic counseling'. References of two genes--RHO and RP1--causing retinitis pigmentosa in the Chinese population were reviewed.

STUDY SELECTION

Literature and data related to genetic markers for retinitis pigmentosa.

DATA SYNTHESIS

The genetics of retinitis pigmentosa is complex. It can be sporadic or familial, with heterogeneous transmission modes. Retinitis pigmentosa is associated with nearly 40 chromosomal loci, where 32 candidate genes have been identified. A large number of mutations are known to cause retinitis pigmentosa. But no single mutation alone accounts for more than 10% of unrelated retinitis pigmentosa patients. Genetic tests for retinitis pigmentosa require screening for a consort of mutations in a large number of genes. High throughput screening technology such as denaturing high performance liquid chromatography and automated DNA sequencing should make such tests feasible.

CONCLUSIONS

Rapid developments in the understanding of the genetics of retinitis pigmentosa have helped to establish genetic tests of clinical value. The complex mode of inheritance nonetheless makes genetic counselling difficult, even in the presence of positive genetic screening results.

Gene mutations in retinitis pigmentosa and their clinical implications

Retinitis pigmentosa (RP) is a group of inherited progressive retinal diseases affecting about 1 in 3500 people worldwide. So far, there is no prevention or cure, with permanent visual loss or even blindness the ultimate consequence usually after midlife. The genetics of RP are complex. It can be sporadic, autosomal dominant, autosomal recessive, or X-linked. Thirty-two genes are known to be associated with RP, sometimes the same gene gets involved in different inheritance traits. Some RP cases have a digenic cause. About 60% RP cases still have no known genetic cause. A large number of mutations cause RP, and they can be deletions, insertions, or substitutions that cause missense mutations or truncations. The RHO, RP1, and RPGR genes contribute the greatest number of known mutations causative of RP. But there is no single mutation that alone accounts for more than 10% of unrelated patients. Genetic testing for RP therefore requires screening for a group of genes. High-throughput and automated sequence detection technologies are essential. Due to the complexity in phenotype and genetics, and the fact that RP is untreatable, genetic testing for presymptomatic diagnosis of RP is controversial. Meanwhile, new genes are still to be identified, mostly by family linkage and sib-pair analysis. Research on gene therapy for RP requires information on gene mutations causative of RP.

Absence of myocilin and optineurin mutations in a large Philippine family with juvenile onset primary open angle glaucoma

PURPOSE

To analyze the role of the two primary open angle glaucoma (POAG) genes, myocilin (MYOC) and optineurin (OPTN), in a large Philippine family segregating autosomal dominant juvenile onset open angle glaucoma (JOAG).

METHODS

The coding sequences of the MYOC and OPTN genes were screened in 27 family members by polymerase chain reaction and direct sequencing. The specific MYOC promoter polymorphism (MYOC.mtl) was identified by restriction endonuclease assay. All of the ABI MD-10 microsatellite markers on chromosomes 1, 2, 3, 7, 8, and 10, which harbor the six known POAG loci, were analyzed for linkage with POAG.

RESULTS

No mutation was identified in this large kindred. Instead, three polymorphisms (-80G->A, -1000G->C, R76K) in MYOC and four polymorphisms (T34T, M98K, R545Q, IVS7+24G->A) in OPTN were found. All markers flanking the six known POAG loci gave LOD scores not more than 1.1. Non-parametric linkage analysis for all these markers resulted in p values more than 0.05.

CONCLUSIONS

Both mutation testing and linkage analysis provide strong evidence against MYOC and OPTN being the causative gene in this large family. It indicates that unidentified genes will underlie the occurrence of glaucoma in this family.