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Genetic study of Diabetic Retinopathy: Recruitment methodology and analysis of baseline characteristics.
Abstract
Diabetic retinopathy (DR) is a blinding disease of increasing prevalence, caused by a complex interplay of genetic and environmental factors. Here we describe the patient recruitment methodology, case and control definitions, and clinical characteristics of a study sample to be used for genome-wide association (GWAS) analysis to detect genetic risk variants of DR.
1669 participants with either type 1 (T1) or type 2 (T2) diabetes mellitus (DM) aged 18 to 95 years were recruited in Australian hospital clinics. Individuals with T2DM had disease duration of at least 5 years, and were taking oral hypoglycemic medication, and/or insulin therapy. Participants underwent ophthalmic examination. Medical history and biochemistry results were collected. Venous blood was obtained for genetic analysis.
683 diabetic cases (178 T1DM and 505 T2DM participants) with sight-threatening DR, defined as severe non-proliferative DR (NPDR), proliferative DR (PDR) or diabetic macular edema (DME) were included in this analysis. 812 individuals with DM but no DR or minimal NPDR were recruited as controls (191 with T1DM and 621 with T2DM). The presence of sight-threatening DR was significantly correlated with DM duration, hypertension, nephropathy, neuropathy, HbA1C and BMI. DME was associated with T2DM (p<0.001), whereas PDR was associated with T1DM (p<0.001).
Adoption of a case-control study design involving extremes of the DR phenotype makes this a suitable cohort, for a well-powered GWAS to detect genetic risk variants for DR.
... Australian participants in the discovery cohort were recruited from the locations listed in the ESM between 2006 and 2011, as previously described [20]. Replication cohorts were recruited between 2011 and 2013 from these sites, as well as from additional sites listed in the ESM. ...
... Discovery cohort Patients of at least 18 years of age who were receiving medical treatment for type 2 diabetes mellitus for at least 5 years were invited to participate, as previously described [20]. Retinopathy status was determined from direct ophthalmic examination by the treating ophthalmologist and was graded according to modified Early Treatment in Diabetic Retinopathy Study (ETDRS) criteria [21]. ...
... Biochemistry results were collected, including HbA 1c , serum lipids and renal function tests. A detailed description of all clinical variables collected has been previously published [20]. DNA was extracted from whole blood using QIAamp Blood DNA Maxi Kits (Qiagen, Chadstone Centre, VIC, Australia). ...
Diabetic retinopathy is a serious complication of diabetes mellitus and can lead to blindness. A genetic component, in addition to traditional risk factors, has been well described although strong genetic factors have not yet been identified. Here, we aimed to identify novel genetic risk factors for sight-threatening diabetic retinopathy using a genome-wide association study.
Retinopathy was assessed in white Australians with type 2 diabetes mellitus. Genome-wide association analysis was conducted for comparison of cases of sight-threatening diabetic retinopathy (n = 336) with diabetic controls with no retinopathy (n = 508). Top ranking single nucleotide polymorphisms were typed in a type 2 diabetes replication cohort, a type 1 diabetes cohort and an Indian type 2 cohort. A mouse model of proliferative retinopathy was used to assess differential expression of the nearby candidate gene GRB2 by immunohistochemistry and quantitative western blot.
The top ranked variant was rs3805931 with p = 2.66 × 10(-7), but no association was found in the replication cohort. Only rs9896052 (p = 6.55 × 10(-5)) was associated with sight-threatening diabetic retinopathy in both the type 2 (p = 0.035) and the type 1 (p = 0.041) replication cohorts, as well as in the Indian cohort (p = 0.016). The study-wide meta-analysis reached genome-wide significance (p = 4.15 × 10(-8)). The GRB2 gene is located downstream of this variant and a mouse model of retinopathy showed increased GRB2 expression in the retina.
Genetic variation near GRB2 on chromosome 17q25.1 is associated with sight-threatening diabetic retinopathy. Several genes in this region are promising candidates and in particular GRB2 is upregulated during retinal stress and neovascularisation.
... Both pupils were dilated with 1% tropicamide and 10% phenylephrine as recommended by National Health and Medical Research Council guidelines. 9 A research officer conducted a medical interview and filled in a standard questionnaire obtaining information on demographics such as age, gender, self-reported ethnicity, ocular and medical history, other complications of diabetes (both microvascular and macrovascular disease) and cardiovascular risk factors. We used the Australian Bureau of Statistics Standard Classification of Cultural and Ethnic Groups 10 for this study. ...
... The overall prevalence of any DR found in our study is close to that reported from similar clinic-based studies in Australia and overseas. For example, a 2013 Australian clinic study reported any DR prevalence of 59.4% in clinic participants, 9 while the 2017 population-based National Eye Health Survey found lower rates in the general population with self-reported diabetes of 28.5%. 6 Our main findings of differences in ethnic rates of DR are also consistent with overseas reports, where we found lower rates of any DR in Europeans and East Asians. ...
Objective
There are limited data on the influence of ethnicity on diabetic retinopathy (DR). We sought to determine the distribution of DR by ethnic group in Australia.
Design
Clinic-based cross-sectional study.
Setting
Participants with diabetes in a defined geographical region of Sydney, Australia, who attended a tertiary retina referral clinic.
Participants
The study recruited 968 participants.
Intervention
Participants underwent a medical interview and retinal photography and scanning.
Primary outcome measures
DR was defined from two-field retinal photographs. Diabetic macular oedema (DMO) was defined from spectral domain optical coherence tomography (OCT-DMO). The main outcomes were any DR, proliferative DR (PDR), clinically significant macular oedema (CSME), OCT-DMO and sight-threatening DR (STDR).
Results
There was high proportion of any DR (52.3%), PDR (6.3%), CSME (19.7%), OCT-DMO (28.9%) and STDR (31.5%) in people attending a tertiary retinal clinic. Participants of Oceanian ethnicity had the highest proportion of any DR and STDR (70.4% and 48.1%, respectively), while the lowest proportion was in participants of East Asian ethnicity (38.3% and 15.8%, respectively). Proportion of any DR and STDR in Europeans was 54.5% and 30.3%, respectively. Independent predictive factors for diabetic eye disease were ethnicity, longer duration of diabetes, higher glycated haemoglobin and higher blood pressure. Even after adjusting for risk factors, Oceanian ethnicity remained associated with twofold higher odds of any DR (adjusted OR 2.10, 95% CI 1.10 to 4.00) and all other forms of DR including STDR (adjusted OR 2.22, 95% CI 1.19 to 4.15).
Conclusion
In people attending a tertiary retinal clinic, the proportion of people with DR varies among ethnic groups. The high proportion in persons of Oceanian ethnicity suggests a need for targeted screening of this at-risk group. In addition to traditional risks factors, ethnicity may be an additional independent predictor of DR.
... This retrospective, cross sectional study adhered to the tenets of the Declaration of Helsinki. Written informed consent was obtained from all study participants, who have been previously described [13,15]. Briefly, patients with medically treated type 2 diabetes for at least 5-years were recruited and underwent a thorough ophthalmological examination. ...
... A strength of this study is the size of the original cohort relative to other DR studies [15], and the detailed clinical evaluation of the participants. Stratifying the sight-threatening phenotype of our earlier study [13] into DME and PDR provided more homogeneous groups for analysis. ...
Background:
Diabetic macular edema (DME) and proliferative diabetic retinopathy (PDR) are sight-threatening complications of diabetes mellitus and leading causes of adult-onset blindness worldwide. Genetic risk factors for diabetic retinopathy (DR) have been described previously, but have been difficult to replicate between studies, which have often used composite phenotypes and been conducted in different populations. This study aims to identify genetic risk factors for DME and PDR as separate complications in Australians of European descent with type 2 diabetes.
Methods:
Caucasian Australians with type 2 diabetes were evaluated in a genome-wide association study (GWAS) to compare 270 DME cases and 176 PDR cases with 435 non-retinopathy controls. All participants were genotyped by SNP array and after data cleaning, cases were compared to controls using logistic regression adjusting for relevant covariates.
Results:
The top ranked SNP for DME was rs1990145 (p = 4.10 × 10- 6, OR = 2.02 95%CI [1.50, 2.72]) on chromosome 2. The top-ranked SNP for PDR was rs918519 (p = 3.87 × 10- 6, OR = 0.35 95%CI [0.22, 0.54]) on chromosome 5. A trend towards association was also detected at two SNPs reported in the only other reported GWAS of DR in Caucasians; rs12267418 near MALRD1 (p = 0.008) in the DME cohort and rs16999051 in the diabetes gene PCSK2 (p = 0.007) in the PDR cohort.
Conclusion:
This study has identified loci of interest for DME and PDR, two common ocular complications of diabetes. These findings require replication in other Caucasian cohorts with type 2 diabetes and larger cohorts will be required to identify genetic loci with statistical confidence. There is considerable overlap in the patient cohorts with each retinopathy subtype, complicating the search for genes that contribute to PDR and DME biology.
... Secondary to the binding of glycation end products to their corresponding receptors Gao anchored on the surface of immune cells and endothelial cells, various proinflammatory cytokines, including tumor necrosis factor-alpha (TNF-α), are synthetized and secreted [3]. It was reported that TNF-α was mainly involved in the destruction of the blood retinal barrier and the formation of new blood vessels [5]. The research conducted by Yao et al. [6] suggested that the expression of TNF-α in DR patients was significantly distinct from that in healthy controls, and inhibition of TNF has shown promising outcomes in preventing the progression of DR in the mice diabetic model [7]. ...
Background:
Mounting evidence has suggested tumor necrosis factor-alpha (TNF-α) can promote the development of diabetic retinopathy (DR), and TNF-α gene variants may influence DR risk. However, the results are quite different.
Objectives:
To comprehensively address this issue, we performed the meta-analysis to evaluate the association of TNF-α-308 G/A and -238 G/A polymorphism with DR.
Method:
Data were retrieved in a systematic manner and analyzed using STATA Statistical Software. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of associations. Allelic and genotypic comparisons between cases and controls were evaluated.
Results:
For the TNF-α-308 G/A polymorphism, overall analysis suggested a marginal association with DR [the OR(95%CI) of (GA versus GG), (GA + AA) versus GG, and (A versus G) are 1.21(1.04, 1.41), 1.20(1.03, 1.39), and 1.14(1.01, 1.30), respectively]. And the subgroup analysis indicated an enhanced association among the European population. For the TNF-α-238 G/A polymorphism, there was mild correlation in the entire group [the OR(95%CI) of (GA versus GG) is 1.55(1.14,2.11) ], which was strengthened among the Asian population.
Conclusion:
The meta-analysis suggested that -308 A and -238 A allele in TNF-α gene potentially increased DR risk and showed a discrepancy in different ethnicities.
... The mean age of our cohort was 58.2 years and 56.8% of our cohort was male, mean HbA1c was 8.4% and 50% of the cohort were ex-smokers or current smokers. These results are similar to those from other Australian cohorts of patients with diabetes, 25 suggesting our population is representative and recruitment is not biased. ...
Purpose
The population prevalence of diabetic macular oedema (DME) is unclear. Previous estimates have depended on photographic grading of clinically significant macular oedema, which is subjective and has resulted in widely varying estimates. With the advent of optical coherence tomography (OCT), the presence and severity of DME can now be assessed objectively and accurately.
Methods
The Liverpool Eye and Diabetes Study (LEADS) is a cross-sectional population-based study of patients with type 1 and type 2 diabetes in a multi-ethnic region of Sydney, Australia, to determine the population prevalence of OCT-defined DME, how this varies by ethnicity and association with systemic factors. This report describes the rationale, methodology and study aims.
Results
To date 646 patients out of an expected sample size of 2000 have been recruited. Baseline data are presented for patients with type 1 (n=75, 11.8%) and type 2 (n=562, 88.2%) diabetes recruited to date. Patients with type 1 diabetes were younger (39.5vs60.7 years), with longer duration of diabetes (18.1vs11.7 years), slightly worse glycaemic control (HbA1c 9.0vs8.3), and less likely to have hypertension (30.7vs71.4%), hypercholesterolaemia (33.3vs74.6%) and obesity (31.1vs51.5%, respectively, all p<0.05).
Conclusions
The LEADS will provide objective estimates of the population prevalence of DME, how this varies with ethnicity and associations with systemic disease.
... For each participant, approximately 8 mL of blood was collected in EDTA blood collection tubes and under- went DNA extraction using the QIAamp Blood DNA Maxi Kits (Qiagen, Venlo, The Netherlands). More detail regarding the data collection method has been described previously 16 . ...
Mitochondrial haplogroups H1, H2 and UK have previously been reported to be associated with proliferative diabetic retinopathy (PDR) in Caucasian patients with diabetes. We aimed to replicate this finding with a larger sample and expand the analysis to include different severities of DR, and diabetic macular edema (DME). Caucasian participants (n = 2935) with either type 1 or type 2 diabetes from the Australian Registry of Advanced Diabetic Retinopathy were enrolled in this study. Twenty-two mitochondrial single nucleotide polymorphisms were genotyped by MassArray and haplogroups reconstructed using Haplogrep. Chi square tests and logistic regressions were used to test associations between haplogroup and DR phenotypes including any DR, non-proliferative DR (NPDR), proliferative DR (PDR) and DME. After stratifying the samples in type 1 and type 2 diabetes groups, and adjusting for sex, age, diabetes duration, concurrent HbA1c and hypertension, neither haplogroups H1, H2, UK, K or JT were associated with any DR, NPDR, PDR or DME.
... Table 1 summarizes the DR phenotyping protocols and covariates by discovery cohort. Phenotyping protocols have been previously described (4,(20)(21)(22)(23)(24)(25)(26)(27)(28)(29), and additional details are in the Supplementary Data. ...
To identify genetic variants associated with diabetic retinopathy (DR), we performed a large multiethnic genome-wide association study. Discovery included eight European cohorts (n = 3,246) and seven African American cohorts (n = 2,611). We meta-analyzed across cohorts using inverse-variance weighting, with and without liability threshold modeling of glycemic control and duration of diabetes. Variants with a P value <1 × 10-5 were investigated in replication cohorts that included 18,545 European, 16,453 Asian, and 2,710 Hispanic subjects. After correction for multiple testing, the C allele of rs142293996 in an intron of nuclear VCP-like (NVL) was associated with DR in European discovery cohorts (P = 2.1 × 10-9), but did not reach genome-wide significance after meta-analysis with replication cohorts. We applied the Disease Association Protein-Protein Link Evaluator (DAPPLE) to our discovery results to test for evidence of risk being spread across underlying molecular pathways. One protein-protein interaction network built from genes in regions associated with proliferative DR was found to have significant connectivity (P = 0.0009) and corroborated with gene set enrichment analyses. These findings suggest that genetic variation in NVL, as well as variation within a protein-protein interaction network that includes genes implicated in inflammation, may influence risk for DR.
... The interaction between AGEs and its receptors on the surface of macrophages and endothelial cells promotes the compound and secretion of multiple pro-inflammatory cytokines, including tumor necrosis factor (TNF-α). It was reported that TNF-α was mainly involved in the destruction of the blood retinal barrier and the formation of new blood vessels, so it was one of the main effective factors of diabetic retinopathy [12]. Many studies had reported that the polymorphism of tumor necrosis factor promoter related to some related diseases, and rs1800629 (TNF-308) was the most widely used single nucleotide polymorphism sites. ...
Aim: Some studies showed that tumor necrosis factor gene polymorphism related to the progression of diabetes mellitus. The aim of this study is to explore the correlation between the gene polymorphism of tumor necrosis factor and diabetic retinopathy in clinical cases. Methods: We took the clinical cases as research subjects. The patients with type I and type II diabetes mellitus who had retinopathy and no retinopathy were 120 cases and 100 cases. At the same time, we analyzed gene polymorphism of tumor necrosis factor for all the patients (rs1800629). Results: A allelic gene of rs1800629 related to type I diabetes mellitus. We did not find significant correlation between rs1800629 and diabetic retinopathy by adjusting age, gender, duration of diabetes mellitus, HbALc, high blood pressure, kidney disease and other variables. Conclusion: This study has preliminarily confirmed that functional single nucleotide polymorphism A in promoter region related to type I diabetes mellitus, which had no significant correlation with diabetic retinopathy.
... A detailed description of recruitment protocols and study participants has been reported previously. 4 In brief, patients were required to meet the following inclusion criteria: (1) at least 18 years of age and (2) on medical treatment for DM (either oral hypoglycaemic agents or insulin therapy). Individuals with T2DM were required to be on medical treatment for DM for at least 5 years prior to inclusion in the study. ...
Aim:
To investigate, in a large cohort of 2494 individuals with diabetes mellitus, whether functional single nucleotide polymorphisms in the promoter region of tumour necrosis factor (TNF) and lymphotoxin-alpha (LTA) genes are associated with type of diabetes or presence of diabetic retinopathy.
Methods:
A total of 334 type 1 diabetes and 999 type 2 diabetes participants with sight-threatening diabetic retinopathy, and 260 type 1 diabetes and 901 type 2 diabetes participants with no diabetic retinopathy or minimal non-proliferative diabetic retinopathy, were genotyped for two single nucleotide polymorphisms (rs1800629 and rs361525).
Results:
The A allele of rs1800629 was associated with type 1 diabetes (p < 0.001; odds ratio = 0.62). After adjustment for age, sex, diabetes duration, HbA1c, hypertension and nephropathy, no significant association was found between rs1800629 or rs361525 and sight-threatening diabetic retinopathy.
Conclusion:
An association between the A allele of rs1800629 and type of diabetes was found. No association was found between two promoter variants of TNF and LTA, and diabetic retinopathy in a large cohort of Caucasian patients with type 1 diabetes and type 2 diabetes.
... Furthermore, what was demonstrated is the influence of different allelic forms of cytokine-, chemokine-, and growth factor coding gene on its functional properties on the level of transcription, as well as the relation with DR in patients with T1DM and T2DM. From a diabetologist's and ophthalmologist's perspective, discovering the existence of polymorphic places in genes coding VEGF and TGF cytokines, the aldose reductase gene, paraoxonase (PON1), and the nitrous oxide synthase gene was essential [19][20][21][22][23][24][25]. An interesting discovery was made by Ray et al., who analyzed the occurrence of C/G polymorphism in the promoter region of the VEGF gene in −460 position [24]. ...
The diagnosis and treatment of diabetic retinopathy (DR) in young adults have significantly improved in recent years. Research methods have widened significantly, for example, by introducing spectral optical tomography of the eye. Invasive diagnostics, for example, fluorescein angiography, are done less frequently. The early introduction of an insulin pump to improve the administration of insulin is likely to delay the development of diabetic retinopathy, which is particularly important for young patients with type 1 diabetes mellitus (T1DM). The first years of diabetes occurring during childhood and youth are the most appropriate to introduce proper therapeutic intervention before any irreversible changes in the eyes appear. The treatment of DR includes increased metabolic control, laserotherapy, pharmacological treatment (antiangiogenic and anti-inflammatory treatment, enzymatic vitreolysis, and intravitreal injections), and surgery. This paper summarizes the up-to-date developments in the diagnostics and treatment of DR. In the literature search, authors used online databases, PubMed, and clinitrials.gov and browsed through individual ophthalmology journals, books, and leading pharmaceutical company websites.
Diabetes mellitus frequently results in Diabetic Retinopathy (DR), which results in lesions on the retina that impact on vision. Blindness may result if it is not caught in time. Unfortunately, there is no cure for DR treatment merely preserves vision. Early diagnosis and treatment of DR can greatly lower the risk of visual loss. In contrast to computer-aided diagnosis technologies, the manual diagnosis of DR retina fundus images by ophthalmologists is costly, time-consuming, and prone to error. Deep learning has recently risen to prominence as one of the most popular methods for improving performance, particularly in the categorization and interpretation of medical images. Convolutional neural networks are more frequently utilized in medical picture analysis as a deep learning technique since they are extremely. The most cutting-edge ways for classifying and detecting DR colour fundus photos using deep learning techniques have been explored and examined for this paper. Additionally, the colour fundus retina DR datasets have been examined. There are also discussions on several complex subjects that demand further research.
Background. According to the International Diabetes Federation, the number of people with diabetes mellitus is going to increase from 366 to 552 million by 2030. More than 1.5 million patients with diabetes are registered in Ukraine, of which 84–95 % have type 2 diabetes. Diabetic retinopathy (DR) is one of the common diabetes complications, being one of the leading causes of blindness and low vision, in particular in people of occupational age. Metabolic disorders, including activation of the polyol pathway of glucose utilization, play an important role in the pathogenesis of DR, with aldose reductase playing a key role, the activity of which is associated with the polymorphism of its gene, AKR1B1. The study of new metabolic and genetic mechanisms for the development and progression of DR in type 2 diabetes mellitus in patients from the Ukrainian population is an actual task of modern ophthalmology. Purpose: to investigate and generalize new genetically determined risk factors for diabetic retinopathy in type 2 diabetes mellitus. Materials and methods. The study involved 409 participants, who were divided into four groups: 1 — comparison cohort (98 people without diabetes mellitus type 2); 2 — 76 patients (stage I DR, without fundus changes); 3 — 64 individuals with non-proliferative DR; 4 — 64 patients with proliferative DR; control group for genetic researches included 107 ophthalmologically healthy individuals. All patients underwent blood sampling for molecular genetic research by puncture of the ulnar vein and aspiration of 2.5 ml of blood through a 23G 5.0 ml disposable syringe (Hemoplast, Etalon+, Ukraine), followed by a release into a 3.0 ml container (Vacuette K3E K3EDTA, Greiner Bio-One, Austria). Distribution of polymorphic alleles and genotypes of rs759853 and rs9640883 aldose reductase gene (AKR1B1) in patients with non-proliferative DR, proliferative DR and in the control group and their association with disease and effects on the occurrence, mechanisms of development and progression of DR were studied. Based on the conducted researches, a model of DR development prognosis was developed by construction of multiple regression with sufficient reliability of degree of influence of independent variables on a calculated indicator. Results. As a result of our research, we identified new genetically determined risk factors for the development and progression of the different stages of DR in patients with diabetes mellitus type 2, namely the role of polymorphic alleles and genotypes rs759853 and rs9640883 of the AKR1B1 gene. The developed logistic regression models found that the risk of DR incidence is five times lower in carriers of the G/G and G/A genotypes compared to carriers of the A/A genotype rs759853 polymorphism (p < 0.001). It was found that the risk is twice as high (p = 0.01) for carriers of the G/G genotype rs9640883 compared to the A/A + G/A genotypes. The risk of developing proliferative DR is 3.3 times lower in carriers of the G/G genotype and 2.5 times lower in carriers of the G/A genotype compared to carriers of the A/A genotype rs759853. Conclusions. Therefore, on the basis of our clinical, ophthalmological, molecular genetic and statistical studies we have identified new risk factors for the development and progression of different stages of DR in patients with diabetes mellitus type 2. Mathematical models of development and progression of different stages of DR in patients with diabetes type 2 were built.
Purpose: To identify functionally related genes associated with diabetic retinopathy (DR) risk using gene set enrichment analyses (GSEA) applied to genome-wide association study (GWAS) meta-analyses.
Methods: We analyzed DR GWAS meta-analyses performed on 3,246 Europeans and 2,611 African Americans with type 2 diabetes. Gene sets relevant to five key DR pathophysiology processes were investigated: tissue injury, vascular events, metabolic events and glial dysregulation, neuronal dysfunction, and inflammation. Keywords relevant to these processes were queried in four pathway and ontology databases. Two GSEA methods, Meta-Analysis Gene set Enrichment of variaNT Associations (MAGENTA) and Multi-marker Analysis of GenoMic Annotation (MAGMA) were used. Gene sets were defined to be enriched for gene associations with DR if the P value corrected for multiple testing (Pcorr) was <.05.
Results: Five gene sets were significantly enriched for multiple modest genetic associations with DR in one method (MAGENTA or MAGMA) and also at least nominally significant (uncorrected P <.05) in the other method. These pathways were regulation of the lipid catabolic process (2-fold enrichment, Pcorr=.014); nitric oxide biosynthesis (1.92-fold enrichment, Pcorr=.022); lipid digestion, mobilization and transport (1.6-fold enrichment, P=.032); apoptosis (1.53-fold enrichment, P=.041); and retinal ganglion cell degeneration (2-fold enrichment, Pcorr=.049). The interferon gamma (IFNG) gene, previously implicated in DR by protein-protein interactions in our GWAS, was among the top ranked genes in the nitric oxide pathway (best variant P=.0001).
Conclusions: These GSEA indicate that variants in genes involved in oxidative stress, lipid transport and catabolism and cell degeneration are enriched for genes associated with DR risk.
Background Growing evidence has indicated that tumor necrosis factor (TNF)-α is a candidate for increasing risk of diabetic retinopathy. Lots of researches have suggested that the variation of the TNF-α gene promoter may play a vital role in the risk of this disease. To solve this issue more clearly, we performed an updated meta-analysis to evaluate the relationship of TNF-α -308 G>A polymorphism with diabetic retinopathy in diabetes mellitus. Methods Literatures were retrieved in a systematic manner and analyzed using STATA Statistical Software. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were adopted to estimate the strength of association. Results Eight studies with 1, 698 cases and 2, 064 controls were included. Genotypic and allelic comparisons between cases and controls were evaluated. Integral analysis shows a marginal association of the TNF-α -308 A allele polymorphism with diabetic retinopathy. Additionally, in stratified analysis by ethnicity, an association among the European population was found. Conclusions Our meta-analysis proved that -308 A allele polymorphism in the TNF-α gene potentially raised the risk of diabetic retinopathy and presented a differential frequency in distinct ethnicities.
Aims:
This study aimed to investigate whether the single-nucleotide polymorphism (SNP) rs2910164 residing within microRNA-146a (miR-146a) is associated with diabetic microvascular complications diabetic nephropathy (DN), proliferative diabetic retinopathy (PDR) or diabetic macular oedema (DME) in either Caucasian patients with type 1 (T1DM) or type 2 (T2DM) diabetes mellitus.
Methods:
Caucasian patients with T1DM (n = 733) or T2DM (n = 2215) were recruited from ophthalmology, renal and endocrine clinics in Australia and the UK. Patients with T2DM were required to have diabetes mellitus (DM) for at least 5 years and be on treatment with oral hypoglycaemic drugs or insulin. In total, 890 participants had DN (168 with T1DM and 722 with T2DM), 731 had PDR (251 with T1DM and 480 with T2DM) and 1026 had DME (170 with T1DM and 856 with T2DM). Participants were genotyped for SNP rs2910164 in miR-146a. Analyses investigating association were adjusted for relevant clinical covariates including age, sex, DM duration, HbA1c and hypertension.
Results:
A significant association was found between the C allele of rs2910164 and DN in the T1DM group (OR 1.93; CI 1.23-3.03; P = 0.004), but no association found in the T2DM group (OR 1.05; CI 0.83-1.32; P = 0.691). In the subset of T2DM patients, the C allele was specifically associated with DME (OR 1.25; CI 1.03-1.53; P = 0.025). No association with DME was found in the T1DM group (OR 0.87; CI 0.54-1.42); P = 0.583), or with PDR for either type of DM.
Conclusions:
Rs2910164 is significantly associated with microvascular complications DN in patients with T1DM and DME in patients with T2DM.
To investigate associations between single nucleotide polymorphisms (SNPs) in the VEGFC gene and the development of diabetic retinopathy (DR) in white patients with type 1 diabetes mellitus (T1DM) or type 2 diabetes mellitus (T2DM).
Cross-sectional, case control study.
White patients with T1DM or T2DM (n = 2899) were recruited from ophthalmology and endocrine clinics in Australia and the United Kingdom. Patients with T2DM were required to have diabetes mellitus (DM) for at least 5 years and be receiving oral hypoglycemic treatment or insulin.
Participants were categorized according to their worst-ever DR grading, as having "no DR" (no history of nonproliferative DR [NPDR], proliferative DR [PDR], or diabetic macular edema [DME]) or "any DR" (further subclassified as NPDR or PDR, without or with DME). Clinical characteristics, glycemic control (hemoglobin A1c [HbA1c]), and presence of diabetic complications were determined at recruitment. Genotyping was performed for 13 VEGFC tag SNPs.
Odds ratios (ORs) were determined for associations with DR of VEGFC tag SNPs, individually and within haplotypes. Logistic regression was used to adjust for clinical covariates, including DM type, age, sex, DM duration, hypertension, nephropathy, HbA1c, and smoking.
Participants with DM but "no DR" (n = 980) were compared with 1919 participants with DM and "any DR." Three VEGFC SNPs were associated with DR after logistic regression: rs17697419 (P = 0.001; OR, 0.67; confidence interval [CI], 0.52-0.85), rs17697515 (P = 0.001; OR, 0.62; CI, 0.47-0.81), and rs2333526 (P = 0.005; OR, 0.69; CI, 0.54-0.90). rs17697515 Was also specifically associated with DME in those with T2DM (P = 0.004; OR, 0.53; CI, 0.35-0.82). Haplotype analysis revealed 2 significantly associated haplotypes, both protective against DR development.
Significant associations were found between VEGFC tag SNPs (individually and within haplotypes) and the presence of any DR or DME in white participants with T1DM and T2DM.
Copyright © 2015 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.
Primary angle closure glaucoma (PACG) is a major cause of blindness worldwide. We conducted a genome-wide association study (GWAS) followed by replication in a combined total of 10,503 PACG cases and 29,567 controls drawn from 24 countries across Asia, Australia, Europe, North America, and South America. We observed significant evidence of disease association at five new genetic loci upon meta-analysis of all patient collections. These loci are at EPDR1 rs3816415 (odds ratio (OR) = 1.24, P = 5.94 × 10(-15)), CHAT rs1258267 (OR = 1.22, P = 2.85 × 10(-16)), GLIS3 rs736893 (OR = 1.18, P = 1.43 × 10(-14)), FERMT2 rs7494379 (OR = 1.14, P = 3.43 × 10(-11)), and DPM2-FAM102A rs3739821 (OR = 1.15, P = 8.32 × 10(-12)). We also confirmed significant association at three previously described loci (P < 5 × 10(-8) for each sentinel SNP at PLEKHA7, COL11A1, and PCMTD1-ST18), providing new insights into the biology of PACG.
Background
Diabetic retinopathy (DR) is a leading cause of preventable blindness in adults. To identify genetic contributions in DR, we studied 2071 type 2 diabetics.Methods/ResultsWe first conducted a genome-wide association study of 1007 individuals, comparing 570 subjects with≥8 years duration without DR (controls) with 437 PDR (cases) in the Chinese discovery cohort. Cases and controls were similar for HbA1c, diabetes duration, and body mass index. Association analysis with imputed data identified 3 novel loci: TBC1D4-COMMD6-UCHL3 (rs9565164, p=1.3x10(-7)), LRP2-BBS5 (rs1399634, p=2.0x10(-6)), and ARL4C-SH3BP4 (rs2380261, p=2.1x10(-6)). Analysis of an independent cohort of 585 Hispanics diabetics with or without DR though did not confirm these signals, these genes are still of particular interest because they are involved in insulin regulation, inflammation, lipid signaling, and apoptosis pathways, all of which are possibly involved with DR.Conclusion
Our finding nominates possible novel loci as potential DR susceptibility genes in the Chinese that are independent of the level of HbA1c and duration of diabetes and may provide insight into the pathophysiology of DR.
Vascular endothelial growth factor (VEGF) is a key chemokine involved in tissue growth and organ repair processes, particularly angiogenesis. Elevated circulating VEGF levels are believed to play a role in type 2 diabetes (T2D) microvascular complications, especially diabetic retinopathy. Recently, a genome-wide association study identified two common single nucleotide polymorphisms (SNPs; rs6921438 and rs10738760) explaining nearly half of the variance in circulating VEGF levels. Considering the putative contribution of VEGF to T2D and its complications, we aimed to assess the effect of these VEGF-related SNPs on the risk of T2D, nephropathy and retinopathy, as well as on variation in related traits.
To investigate whether variants in cardiovascular candidate genes, some of which have been previously associated with type 2 diabetes (T2D), diabetic retinopathy (DR), and diabetic nephropathy (DN), are associated with DR in the Candidate gene Association Resource (CARe).
Persons with T2D who were enrolled in the study (n = 2691) had fundus photography and genotyping of single nucleotide polymorphisms (SNPs) in 2000 candidate genes. Two case definitions were investigated: Early Treatment Diabetic Retinopathy Study (ETDRS) grades ≥ 14 and ≥ 30. The χ² analyses for each CARe cohort were combined by Cochran-Mantel-Haenszel (CMH) pooling of odds ratios (ORs) and corrected for multiple hypothesis testing. Logistic regression was performed with adjustment for other DR risk factors. Results from replication in independent cohorts were analyzed with CMH meta-analysis methods.
Among 39 genes previously associated with DR, DN, or T2D, three SNPs in P-selectin (SELP) were associated with DR. The strongest association was to rs6128 (OR = 0.43, P = 0.0001, after Bonferroni correction). These associations remained significant after adjustment for DR risk factors. Among other genes examined, several variants were associated with DR with significant P values, including rs6856425 tagging α-l-iduronidase (IDUA) (P = 2.1 × 10(-5), after Bonferroni correction). However, replication in independent cohorts did not reveal study-wide significant effects. The P values after replication were 0.55 and 0.10 for rs6128 and rs6856425, respectively.
Genes associated with DN, T2D, and vascular diseases do not appear to be consistently associated with DR. A few genetic variants associated with DR, particularly those in SELP and near IDUA, should be investigated in additional DR cohorts.
Hyperglycemia and long duration of diabetes are widely recognized risk factors for diabetic retinopathy, but inherited susceptibility may also play a role because retinopathy aggregates in families. A genome-wide linkage analysis was conducted in 211 sibships in which > or =2 siblings had diabetes and retinal photographs were available from a longitudinal study. These sibships were a subset of 322 sibships who had participated in a previous linkage study of diabetes and related traits; they comprised 607 diabetic individuals in 725 sibpairs. Retinal photographs were graded for presence and severity of diabetic retinopathy according to a modification of the Airlie House classification system. The grade for the worse eye was adjusted for age, sex, and diabetes duration and analyzed as a quantitative trait. Heritability of diabetic retinopathy in this group was 18% (95% CI 2-36). A genome-wide linkage analysis using variance components modeling found evidence of linkage on chromosome 1p. Using single-point analysis, the peak logarithm of odds (LOD) was 3.1 for marker D1S3669 (34.2 cM), whereas with multipoint analysis the peak LOD was 2.58 at 35 cM. No other areas of suggestive linkage were found. We propose that an area on chromosome 1 may harbor a gene or genes conferring susceptibility to diabetic retinopathy.
To demonstrate superiority of ranibizumab 0.5 mg monotherapy or combined with laser over laser alone based on mean average change in best-corrected visual acuity (BCVA) over 12 months in diabetic macular edema (DME).
A 12-month, randomized, double-masked, multicenter, laser-controlled phase III study.
We included 345 patients aged ≥18 years, with type 1 or 2 diabetes mellitus and visual impairment due to DME.
Patients were randomized to ranibizumab + sham laser (n = 116), ranibizumab + laser (n = 118), or sham injections + laser (n = 111). Ranibizumab/sham was given for 3 months then pro re nata (PRN); laser/sham laser was given at baseline then PRN (patients had scheduled monthly visits).
Mean average change in BCVA from baseline to month 1 through 12 and safety.
Ranibizumab alone and combined with laser were superior to laser monotherapy in improving mean average change in BCVA letter score from baseline to month 1 through 12 (+6.1 and +5.9 vs +0.8; both P<0.0001). At month 12, a significantly greater proportion of patients had a BCVA letter score ≥15 and BCVA letter score level >73 (20/40 Snellen equivalent) with ranibizumab (22.6% and 53%, respectively) and ranibizumab + laser (22.9% and 44.9%) versus laser (8.2% and 23.6%). The mean central retinal thickness was significantly reduced from baseline with ranibizumab (-118.7 μm) and ranibizumab + laser (-128.3 μm) versus laser (-61.3 μm; both P<0.001). Health-related quality of life, assessed through National Eye Institute Visual Function Questionnaire (NEI VFQ-25), improved significantly from baseline with ranibizumab alone and combined with laser (P<0.05 for composite score and vision-related subscales) versus laser. Patients received ∼7 (mean) ranibizumab/sham injections over 12 months. No endophthalmitis cases occurred. Increased intraocular pressure was reported for 1 patient each in the ranibizumab arms. Ranibizumab monotherapy or combined with laser was not associated with an increased risk of cardiovascular or cerebrovascular events in this study.
Ranibizumab monotherapy and combined with laser provided superior visual acuity gain over standard laser in patients with visual impairment due to DME. Visual acuity gains were associated with significant gains in VFQ-25 scores. At 1 year, no differences were detected between the ranibizumab and ranibizumab + laser arms. Ranibizumab monotherapy and combined with laser had a safety profile in DME similar to that in age-related macular degeneration.
To identify genetic loci for severe diabetic retinopathy, 286 Mexican-Americans with type 2 diabetes from Starr County, Texas, completed physical examinations including fundus photography for diabetic retinopathy grading. Individuals with moderate-to-severe non-proliferative and proliferative diabetic retinopathy were defined as cases. Direct genotyping was performed using the Affymetrix GeneChip Human Mapping 100 K Set, and SNPs passing quality control criteria were used to impute markers available in HapMap Phase III Mexican population (MXL) in Los Angeles, California. Two directly genotyped markers were associated with severe diabetic retinopathy at a P-value less than .0001: SNP rs2300782 (P = 6.04 × 10(-5)) mapped to an intron region of CAMK4 (calcium/calmodulin-dependent protein kinase IV) on chromosome 5, and SNP rs10519765 (P = 6.21 × 10(-5)) on chromosomal 15q13 in the FMN1 (formin 1) gene. Using well-imputed markers based on the HapMap III Mexican population, we identified an additional 32 SNPs located in 11 chromosomal regions with nominal association with severe diabetic retinopathy at P-value less than .0001. None of these markers were located in traditional candidate genes for diabetic retinopathy or diabetes itself. However, these signals implicate genes involved in inflammation, oxidative stress and cell adhesion for the development and progression of diabetic retinopathy.
Aldose reductase (ALR) is involved in diabetic microvascular damage via the polyol pathway. A recent meta-analysis found genetic variation in the ALR gene (AKR1B1) to be significantly associated with diabetic retinopathy (DR). We investigated the genetic association of AKR1B1 with DR.
The study enrolled 909 individuals with diabetes. Participants were genotyped for an AKR1B1 (CA)n microsatellite and 14 tag single nucleotide polymorphisms, and ophthalmological assessment was performed.
A total of 514 individuals were found to have DR. rs9640883 was significantly associated with DR (P = 0.0005). However, AKR1B1 variation was not independently associated with DR development after adjusting for relevant clinical parameters. rs9640883 was associated with duration of diabetes (P = 0.002).
Many previous reports have failed to account for known risk factors for DR. The commonly reported association of AKR1B1 with DR may be due to an association of the gene with younger age at onset of diabetes.
Diabetic retinopathy is a sight-threatening microvascular complication of diabetes with a complex multifactorial pathogenesis. A systematic meta-analysis was undertaken to collectively assess genetic studies and determine which previously investigated polymorphisms are associated with diabetic retinopathy.
All studies investigating the association of genetic variants with the development of diabetic retinopathy were identified in PubMed and ISI Web of Knowledge. Crude odds ratios (ORs) and 95% CIs were calculated for single nucleotide polymorphisms and microsatellite markers previously investigated in at least two published studies.
Twenty genes and 34 variants have previously been studied in multiple cohorts. The aldose reductase (AKR1B1) gene was found to have the largest number of polymorphisms significantly associated with diabetic retinopathy. The z-2 microsatellite was found to confer risk (OR 2.33 [95% CI 1.49-3.64], P = 2 x 10(-4)) in type 1 and type 2 diabetes and z+2 to confer protection (0.58 [0.36-0.93], P = 0.02) against diabetic retinopathy in type 2 diabetes regardless of ethnicity. The T allele of the AKR1B1 promoter rs759853 variant is also significantly protective against diabetic retinopathy in type 1 diabetes (0.5 [0.35-0.71], P = 1.00 x 10(-4)), regardless of ethnicity. These associations were also found in the white population alone (P < 0.05). Polymorphisms in NOS3, VEGF, ITGA2, and ICAM1 are also associated with diabetic retinopathy after meta-analysis.
Variations within the AKR1B1 gene are highly significantly associated with diabetic retinopathy development irrespective of ethnicity. Identification of genetic risk factors in diabetic retinopathy will assist in further understanding of this complex and debilitating diabetes complication.
Diabetic retinopathy (DR) and diabetic nephropathy (DN) are serious microvascular complications of diabetes mellitus. Correlations between severity of DR and DN and computed heritability estimates for DR were determined in a large, multiethnic sample of diabetic families. The hypothesis was that (1) the severity of DR correlates with the presence and severity of nephropathy in individuals with diabetes mellitus, and (2) the severity of DR is under significant familial influence in members of multiplex diabetic families.
The Family Investigation of Nephropathy and Diabetes (FIND) was designed to evaluate the genetic basis of DN in American Indians, European Americans, African Americans, and Mexican Americans. FIND enrolled probands with advanced DN, along with their diabetic siblings who were concordant and discordant for nephropathy. These diabetic family members were invited to participate in the FIND-Eye study to determine whether inherited factors underlie susceptibility to DR and its severity. FIND-Eye participants underwent eye examinations and had fundus photographs taken. The severity of DR was graded by using the Early Treatment Diabetic Retinopathy Study Classification (ETDRS). Sib-sib correlations were calculated with the SAGE 5.0 program FCOR, to estimate heritability of retinopathy severity.
This report summarizes the results for the first 2368 diabetic subjects from 767 families enrolled in FIND-Eye; nearly 50% were Mexican American, the largest single ethnicity within FIND. The overall prevalence of DR was high; 33.4% had proliferative DR; 7.5%, 22.8%, and 9.5% had severe, moderate, and mild nonproliferative DR, respectively; 26.6% had no DR. The severity of DR was significantly associated with severity of DN, both by phenotypic category and by increasing serum creatinine concentration (chi(2) = 658.14, df = 20; P < 0.0001). The sib-sib correlation for DR severity was 0.1358 in the total sample and 0.1224 when limited to the Mexican-American sample. Broad sense heritabilities for DR were 27% overall and 24% in Mexican-American families. The polygenic heritability of liability for proliferative DR approximated 25% in this FIND-Eye sample.
These data confirm that the severity of DR parallels the presence and severity of nephropathy in individuals with diabetes mellitus. The severity of DR in members of multiplex diabetic families appears to have a significant familial connection.
A website for performing power calculations for the design of linkage and association genetic mapping studies of complex traits.
Availability: The package is made available athttp://statgen.iop.kcl.ac.uk/gpc/
Contact: s.purcell@iop.kcl.ac.uk
*To whom correspondence should be addressed
We conducted a genome-wide linkage scan for genes contributing to retinopathy risk using 794 diabetes case subjects from 393 Mexican-American families from Starr County, Texas, having at least two diabetic siblings. The sample included 567 retinopathy case subjects comprising 282 affected sibling pairs. Retinopathy was classified as none, early nonproliferative, moderate-to-severe nonproliferative, or proliferative. Using 360 polymorphic markers (average spacing 9.4 cM), we conducted nonparametric linkage analysis followed by ordered-subset analysis (OSA) ranking families by average age of diabetes diagnosis. For any retinopathy, the highest LOD scores including all families were on chromosomes 3 (2.41 at 117 cM) and 12 (2.47 at 15.5). OSA logarithm of odds (LOD) scores >2 for any retinopathy occurred on chromosomes 12 (4.47 at 13.2 cM), 15 (3.65 at 100.6), and 20 (2.67 at 54.1). Scores >2 for either moderate-to-severe nonproliferative or proliferative retinopathy occurred on chromosomes 5 (2.53 at 11.2 cM), 6 (2.28 at 30.6), and 19 (2.21 at 100.6). Thus, unconditional linkage analysis revealed suggestive evidence of linkage with retinopathy on two chromosomes, whereas OSA revealed strong evidence of linkage on two chromosomes, and suggestive evidence on four. Candidate genes were identified in most implicated regions.
The modified Airlie House classification of diabetic retinopathy has been extended for use in the Early Treatment Diabetic Retinopathy Study (ETDRS). The revised classification provides additional steps in the grading scale for some characteristics, separates other characteristics previously combined, expands the section on macular edema, and adds several characteristics not previously graded. The classification is described and illustrated and its reproducibility between graders is assessed by calculating percentages of agreement and kappa statistics for duplicate gradings of baseline color nonsimultaneous stereoscopic fundus photographs. For retinal hemorrhages and/ or microaneurysms, hard exudates, new vessels, fibrous proliferations, and macular edema, agreement was substantial (weighted kappa, 0.61 to 0.80). For soft exudates, intraretinal microvascular abnormalities, and venous beading, agreement was moderate (weighted kappa, 0.41 to 0.60). A double grading system, with adjudication of disagreements of two or more steps between duplicate gradings, led to some improvement in reproducibility for most characteristics.
BACKGROUND
Long-term microvascular and neurologic complications cause major morbidity and mortality in patients with insulin-dependent diabetes mellitus (IDDM). We examined whether intensive treatment with the goal of maintaining blood glucose concentrations close to the normal range could decrease the frequency and severity of these complications.
METHODS
A total of 1441 patients with IDDM -- 726 with no retinopathy at base line (the primary-prevention cohort) and 715 with mild retinopathy (the secondary-intervention cohort) were randomly assigned to intensive therapy administered either with an external insulin pump or by three or more daily insulin injections and guided by frequent blood glucose monitoring or to conventional therapy with one or two daily insulin injections. The patients were followed for a mean of 6.5 years, and the appearance and progression of retinopathy and other complications were assessed regularly.
RESULTS
In the primary-prevention cohort, intensive therapy reduced the adjusted mean risk for the development of retinopathy by 76 percent (95 percent confidence interval, 62 to 85 percent), as compared with conventional therapy. In the secondary-intervention cohort, intensive therapy slowed the progression of retinopathy by 54 percent (95 percent confidence interval, 39 to 66 percent) and reduced the development of proliferative or severe nonproliferative retinopathy by 47 percent (95 percent confidence interval, 14 to 67 percent). In the two cohorts combined, intensive therapy reduced the occurrence of microalbuminuria (urinary albumin excretion of ≥ 40 mg per 24 hours) by 39 percent (95 percent confidence interval, 21 to 52 percent), that of albuminuria (urinary albumin excretion of ≥ 300 mg per 24 hours) by 54 percent (95 percent confidence interval, 19 to 74 percent), and that of clinical neuropathy by 60 percent (95 percent confidence interval, 38 to 74 percent). The chief adverse event associated with intensive therapy was a two-to-threefold increase in severe hypoglycemia.
CONCLUSIONS
Intensive therapy effectively delays the onset and slows the progression of diabetic retinopathy, nephropathy, and neuropathy in patients with IDDM.
Next-generation sequencing technologies are making it possible to study the role of rare variants in human disease. Many studies balance statistical power with cost-effectiveness by (a) sampling from phenotypic extremes and (b) utilizing a two-stage design. Two-stage designs include a broad-based discovery phase and selection of a subset of potential causal genes/variants to be further examined in independent samples. We evaluate three parameters: first, the gain in statistical power due to extreme sampling to discover causal variants; second, the informativeness of initial (Phase I) association statistics to select genes/variants for follow-up; third, the impact of extreme and random sampling in (Phase 2) replication. We present a quantitative method to select individuals from the phenotypic extremes of a binary trait, and simulate disease association studies under a variety of sample sizes and sampling schemes. First, we find that while studies sampling from extremes have excellent power to discover rare variants, they have limited power to associate them to phenotype—suggesting high false-negative rates for upcoming studies. Second, consistent with previous studies, we find that the effect sizes estimated in these studies are expected to be systematically larger compared with the overall population effect size; in a well-cited lipids study, we estimate the reported effect to be twofold larger. Third, replication studies require large samples from the general population to have sufficient power; extreme sampling could reduce the required sample size as much as fourfold. Our observations offer practical guidance for the design and interpretation of studies that utilize extreme sampling. Genet. Epidemiol. 35: 236-246, 2011. © 2011 Wiley-Liss, Inc.
Over 11 years from 1977 a large study of diabetic retinopathy has been conducted in Newcastle and in 1988, 5519 diabetic subjects had been assessed. Where possible, all had retinal photography. Prevalence rates for any retinopathy, proliferative retinopathy and maculopathy were assessed in relation to the known duration of diabetes for subjects diagnosed before or after age 30 years. These data indicate a peak of retinopathy prevalence in the second or third decade of diabetes with slightly lower rates in longer survivors. Treatment with insulin was associated with a higher retinopathy prevalence. Incidence rates for the new development of background retinopathy in previously unaffected subjects show a peak late in the first decade of diabetes in young-onset cases, while in the older-onset group, the peak occurs in the second decade of diabetes. Over all, 8% of diabetics without retinopathy developed it per year. The implications of this data for the routine management of diabetic patients is discussed and the current recommendations for retinal screening by the Australian Diabetes Society are outlined.
To report the 2-year outcomes of the BOLT study, a prospective randomized controlled trial evaluating intravitreous bevacizumab and modified Early Treatment Diabetic Retinopathy Study (ETDRS) macular laser therapy (MLT) in patients with persistent clinically significant macular edema (CSME).
In a 2-year, single-center, randomized controlled trial, 80 patients with center-involving CSME and visual acuity of 20/40 to 20/320 were randomized to receive either bevacizumab or MLT.
Primary outcome: difference in ETDRS best-corrected visual acuity (BCVA) between arms. Secondary outcomes: mean change in BCVA, proportion gaining at least 15 and at least 10 ETDRS letters, losing fewer than 15 and at least 30 letters, change in central macular thickness, ETDRS retinopathy severity, and safety outcomes. Results: At 2 years, mean (SD) ETDRS BCVA was 64.4 (13.3) (ETDRS equivalent Snellen fraction: 20/50) in the bevacizumab arm and 54.8 (12.6) (20/80) in the MLT arm (P=.005). The bevacizumab arm gained a median of 9 ETDRS letters vs 2.5 letters for MLT (P=.005), with a mean gain of 8.6 letters for bevacizumab vs amean loss of 0.5 letters for MLT. Forty-nine percent of patients gained 10 or more letters (P=.001) and 32% gained at least 15 letters (P=.004) for bevacizumab vs 7% and 4% for MLT. Percentage who lost fewer than 15 letters in the MLT arm was 86% vs 100% for bevacizumab (P=.03). Mean reduction in central macular thickness was 146 μm in the bevacizumab arm vs 118 μm in the MLT arm. The median number of treatments over 24 months was 13 for bevacizumab and 4 for MLT.
This study provides evidence supporting longer-term use of intravitreous bevacizumab for persistent center-involving CSME.
Improvements in BCVA and central macular thickness seen with bevacizumab at 1 year were maintained over the second year with a mean of 4 injections.
eudract.ema.europa.eu Identifier: 2007-000847-89
We report a genome-wide association study for open-angle glaucoma (OAG) blindness using a discovery cohort of 590 individuals with severe visual field loss (cases) and 3,956 controls. We identified associated loci at TMCO1 (rs4656461[G] odds ratio (OR) = 1.68, P = 6.1 × 10(-10)) and CDKN2B-AS1 (rs4977756[A] OR = 1.50, P = 4.7 × 10(-9)). We replicated these associations in an independent cohort of cases with advanced OAG (rs4656461 P = 0.010; rs4977756 P = 0.042) and two additional cohorts of less severe OAG (rs4656461 combined discovery and replication P = 6.00 × 10(-14), OR = 1.51, 95% CI 1.35-1.68; rs4977756 combined P = 1.35 × 10(-14), OR = 1.39, 95% CI 1.28-1.51). We show retinal expression of genes at both loci in human ocular tissues. We also show that CDKN2A and CDKN2B are upregulated in the retina of a rat model of glaucoma.
Diabetic retinopathy is a leading cause of blindness. The purpose of this study is to identify novel genetic loci associated with the sight threatening complications of diabetic retinopathy. We performed a meta-analysis of genome-wide association data for severe diabetic retinopathy as defined by diabetic macular edema or proliferative diabetic retinopathy in unrelated cases ascertained from two large, type I diabetic cohorts: the Genetics of Kidney in Diabetes (GoKinD) and the Epidemiology of Diabetes Intervention and Control Trial (EDIC) studies. Controls were other diabetic subjects in the cohort. A combined total of 2829 subjects (973 cases, 1856 controls) were studied on 2 543 887 single nucleotide polymorphisms (SNPs). Subjects with nephropathy were excluded in a sub-analysis of 281 severe retinopathy cases. We also performed an association analysis of 1390 copy number variations (CNVs) using tag SNPs. No associations were significant at a genome-wide level after correcting for multiple measures. The meta-analysis did identify several associations that can be pursued in future replication studies, including an intergenic SNP, rs476141, on chromosome 1 (P-value 1.2 × 10(-7)). The most interesting signal from the CNV analysis came from the sub-group analysis without nephropathy subjects and is rs10521145 (P-value 3.4 × 10(-6)) in the intron of CCDC101, a histone acetyltransferase. This SNP tags the copy number region CNVR6685.1 on chromosome 16 at 28.5 Mb, a gain/loss site. In summary, this study nominates several novel genetic loci associated with the sight-threatening complications of diabetic retinopathy and anticipates future large-scale consortium-based validation studies.
Diabetic retinopathy (DR) is a microvascular complication of diabetes with a complex multifactorial pathogenesis. The aim of this study was to identify the susceptibility genes that increase the risk of DR in type 2 diabetes (T2D) and to further elucidate the underlying mechanism of DR pathogenesis.
A case-control study.
We included 749 unrelated individuals with T2D (174 with DR and 575 without DR) and 100 nondiabetic controls.
We conducted a genome-wide association study using Illumina HumanHap550-Duo BeadChips.
Compared with the genotypic distribution of single nucleotide polymorphisms (SNPs) between subjects with DR and without DR.
Using statistical models, we selected a total of 12 SNPs with P-values <1 × 10(-6) that were associated with DR. After controlling for diabetes duration and hemoglobin A(1C), 9 of the 12 SNPs located on 5 chromosomal regions were found to be associated with DR. Five loci not previously associated with DR susceptibility were identified in and around the following genes: MYSM1 (Myb-like, SWIRM, and MPN domains 1) located on chromosome 1p (odds ratio [OR], 1.50; 95% confidence interval [CI], 1.03-2.20); PLXDC2 (plexin domain-containing 2) located on the chromosome 10p (OR, 1.67; 95% CI, 1.06-2.65); ARHGAP22 (Rho GTPase-activating protein 22) located on chromosome 10q (OR, 1.65; 95% CI, 1.05-2.60); and HS6ST3 (heparan sulfate 6-O-sulfotransferase 3) located on chromosome 13q (OR, 2.33; 95% CI, 1.13-4.77). The SNPs rs13163610 and rs17376456 located in the unknown gene on chromosome 5q were also associated with DR (OR, 3.63; 95% CI, 1.38-9.58).
We identified a genetic association for susceptibility to DR in 5 novel chromosomal regions and PLXDC2 and ARHGAP22, the latter 2 of which are genes implicated in endothelial cell angiogenesis and increased capillary permeability. These findings suggest unsuspected pathways in the pathogenesis of DR.
To determine the prevalence and associations of diabetic retinopathy (DR) within the indigenous Australian population living in central Australia.
1884 individuals aged 20 years or older, living in one of 30 remote communities within the statistical local area of 'central Australia' were recruited for this study. This equated to 36% of those aged 20 years or older and 67% of those aged 40 years or older within this district. Participants were recruited as they presented to the eye clinic at each remote community. Following dilated slit-lamp fundoscopy, the amount of DR in participants with diabetes mellitus (DM) was quantified using the Early Treatment of Diabetic Retinopathy Study criteria. The presence of any DR and vision-threatening DR (clinically significant macular oedema and/or proliferative DR) in one or both eyes was presented.
Of those with diabetes, 22.2% (25.4% of those aged 40 years or older) had any DR and 7.0% (8.4% of those aged 40 years or older) had vision-threatening DR. Both the presence of any DR and vision-threatening DR were associated with advancing age and HbA1c level, but neither subcategory was associated with sex or self-reported hypertension.
Our study has shown similar prevalence rates for DR in indigenous Australians compared with non-indigenous Australians. However, as DM is far more prevalent among indigenous Australians, the proportion of those affected by DR across the population should be considerably higher when compared with non-indigenous Australians.
To report the findings at 1 year of a study comparing repeated intravitreal bevacizumab (ivB) and modified Early Treatment of Diabetic Retinopathy Study (ETDRS) macular laser therapy (MLT) in patients with persistent clinically significant diabetic macular edema (CSME).
Prospective, randomized, masked, single-center, 2-year, 2-arm clinical trial.
A total of 80 eyes of 80 patients with center-involving CSME and at least 1 prior MLT.
Subjects were randomized to either ivB (6 weekly; minimum of 3 injections and maximum of 9 injections in the first 12 months) or MLT (4 monthly; minimum of 1 treatment and maximum of 4 treatments in the first 12 months).
The primary end point was the difference in ETDRS best-corrected visual acuity (BCVA) at 12 months between the bevacizumab and laser arms.
The baseline mean ETDRS BCVA was 55.7+/-9.7 (range 34-69) in the bevacizumab group and 54.6+/-8.6 (range 36-68) in the laser arm. The mean ETDRS BCVA at 12 months was 61.3+/-10.4 (range 34-79) in the bevacizumab group and 50.0+/-16.6 (range 8-76) in the laser arm (P = 0.0006). Furthermore, the bevacizumab group gained a median of 8 ETDRS letters, whereas the laser group lost a median of 0.5 ETDRS letters (P = 0.0002). The odds of gaining > or =10 ETDRS letters over 12 months were 5.1 times greater in the bevacizumab group than in the laser group (adjusted odds ratio, 5.1; 95% confidence interval, 1.3-19.7; P = 0.019). At 12 months, central macular thickness decreased from 507+/-145 microm (range 281-900 microm) at baseline to 378+/-134 microm (range 167-699 microm) (P<0.001) in the ivB group, whereas it decreased to a lesser extent in the laser group, from 481+/-121 microm (range 279-844 microm) to 413+/-135 microm (range 170-708 microm) (P = 0.02). The median number of injections was 9 (interquartile range [IQR] 8-9) in the ivB group, and the median number of laser treatments was 3 (IQR 2-4) in the MLT group.
The study provides evidence to support the use of bevacizumab in patients with center-involving CSME without advanced macular ischemia.
To determine the prevalence and causes of vision loss in Indigenous Australians.
A national, stratified, random cluster sample was drawn from 30 communities across Australia that each included about 300 Indigenous people of all ages. A sample of non-Indigenous adults aged > or = 40 years was also tested at several remote sites for comparison. Participants were examined using a standardised protocol that included a questionnaire (self-administered or completed with the help of field staff), visual acuity (VA) testing on presentation and after correction, visual field testing, trachoma grading, and fundus and lens photography. The data were collected in 2008.
VA; prevalence of low vision and blindness; causes of vision loss; rates of vision loss in Indigenous compared with non-Indigenous adults.
1694 Indigenous children and 1189 Indigenous adults were examined, representing recruitment rates of 84% for children aged 5-15 years and 72% for adults aged > or = 40 years. Rates of low vision (VA < 6/12 to > or = 6/60) were 1.5% (95% CI, 0.9%-2.1%) in children and 9.4% (95% CI, 7.8%-11.1%) in adults. Rates of blindness (VA < 6/60) were 0.2% (95% CI, 0.04%-0.5%) in children and 1.9% (95% CI, 1.1%-2.6%) in adults. The principal cause of low vision in both adults and children was refractive error. The principal causes of blindness in adults were cataract, refractive error and optic atrophy. Relative risks (RRs) of vision loss and blindness in Indigenous adults compared with adults in the mainstream Australian population were 2.8 and 6.2, respectively. By contrast, RRs of vision loss and blindness in Indigenous children compared with mainstream children were 0.2 and 0.6, respectively.
Many causes of vision loss in our sample were readily avoidable. Better allocation of services and resources is required to give all Australians equal access to eye health services.
To identify genetic susceptibility loci for severe diabetic retinopathy, 286 Mexican-Americans with type 2 diabetes from Starr County, Texas completed detailed physical and ophthalmologic examinations including fundus photography for diabetic retinopathy grading. 103 individuals with moderate-to-severe non-proliferative diabetic retinopathy or proliferative diabetic retinopathy were defined as cases for this study. DNA samples extracted from study subjects were genotyped using the Affymetrix GeneChip® Human Mapping 100K Set, which includes 116,204 single nucleotide polymorphisms (SNPs) across the whole genome. Single-marker allelic tests and 2- to 8-SNP sliding-window Haplotype Trend Regression implemented in HelixTreeTM were first performed with these direct genotypes to identify genes/regions contributing to the risk of severe diabetic retinopathy. An additional 1,885,781 HapMap Phase II SNPs were imputed from the direct genotypes to expand the genomic coverage for a more detailed exploration of genetic susceptibility to diabetic retinopathy. The average estimated allelic dosage and imputed genotypes with the highest posterior probabilities were subsequently analyzed for associations using logistic regression and Fisher's Exact allelic tests, respectively. To move beyond these SNP-based approaches, 104,572 directly genotyped and 333,375 well-imputed SNPs were used to construct genetic distance matrices based on 262 retinopathy candidate genes and their 112 related biological pathways. Multivariate distance matrix regression was then used to test hypotheses with genes and pathways as the units of inference in the context of susceptibility to diabetic retinopathy. This study provides a framework for genome-wide association analyses, and implicated several genes involved in the regulation of oxidative stress, inflammatory processes, histidine metabolism, and pancreatic cancer pathways associated with severe diabetic retinopathy. Many of these loci have not previously been implicated in either diabetic retinopathy or diabetes. In summary, CDC73, IL12RB2, and SULF1 had the best evidence as candidates to influence diabetic retinopathy, possibly through novel biological mechanisms related to VEGF-mediated signaling pathway or inflammatory processes. While this study uncovered some genes for diabetic retinopathy, a comprehensive picture of the genetic architecture of diabetic retinopathy has not yet been achieved. Once fully understood, the genetics and biology of diabetic retinopathy will contribute to better strategies for diagnosis, treatment and prevention of this disease.
As part of a population-based study of diabetes mellitus, the 4-year incidence of macular edema and its relationship to various risk factors was examined in a group of younger onset insulin-taking persons (n = 610) and older onset persons (n = 652). The presence of macular edema at the baseline and follow-up examinations was determined from gradings of stereoscopic fundus photographs. The overall incidence of macular edema in the younger onset group was 8.2% (50/610); in the group of older onset persons using insulin, 8.4% (23/273) and in the group of those not using insulin, 2.9% (11/379). The incidence of macular edema was associated with higher level of glycosylated hemoglobin, longer duration of diabetes, and more severe retinopathy at the baseline examination in both younger and older onset groups. These data provide accurate population-based estimates of incidence of macular edema, and suggest that the level of glycemia is a significant risk factor for the development of macular edema.
As part of a population-based study of diabetes mellitus, the incidence of macular edema over a 10-year period and its relation to various risk factors are examined.
There were 891 younger-onset people with a diagnosis of having had diabetes before 30 years of age who were taking insulin at baseline examination and 987 older-onset people with a diagnosis of having had diabetes at 30 years of age or older who participated in baseline and 4-year examinations. Of these, 765 younger-onset and 533 older-onset people also participated in a 10-year examination. The presence of macular edema at baseline and follow-up examinations was determined from gradings of stereoscopic fundus photographs.
The incidence of macular edema over the 10-year period was 20.1% in the younger-onset group, 25.4% in the older-onset group taking insulin, and 13.9% in the older-onset group not taking insulin. The incidence of macular edema over the 10-year period was associated with higher levels of glycosylated hemoglobin and more severe retinopathy in both younger- and older-onset groups, and with being female and increased diastolic blood pressure in the older-onset group.
These data suggest a relatively high incidence of macular edema. The authors' data also suggest that a reduction in hyperglycemia may result in a beneficial decrease in the incidence of macular edema.
To determine whether there are relationships between nephropathy, retinopathy and putative risk factors at points very early in the development of long-term complications of IDDM, we have analyzed baseline data pertinent to nephropathy in the 726 subjects in the primary prevention cohort and the 715 subjects in the secondary intervention cohort of the DCCT. AER correlated positively with CCr and HbA1c in both cohorts and with degree of retinopathy and duration of IDDM in the secondary cohort. Within the secondary cohort only mean BP and HbA1c levels were significantly increased (P < 0.005) in the 73 subjects with AER > or = 28 micrograms/24 hr compared to the 642 subjects with AER < 28 micrograms/24 hr. Stratification of all subjects in the secondary cohort showed significant associations (P < 0.001) between retinopathy level, AER, duration of diabetes at entry and entry HbA1c. Even very early in the development of retinopathy and nephropathy, there is a relationship between them and with level of metabolic control. The prospective studies of the DCCT are designed to answer the question of whether intensive diabetes treatment will affect the development and/or progression of retinopathy, and, possibly, of nephropathy.
Diabetes-specific microvascular disease is a leading cause of blindness, renal failure and nerve damage, and diabetes-accelerated atherosclerosis leads to increased risk of myocardial infarction, stroke and limb amputation. Four main molecular mechanisms have been implicated in glucose-mediated vascular damage. All seem to reflect a single hyperglycaemia-induced process of overproduction of superoxide by the mitochondrial electron-transport chain. This integrating paradigm provides a new conceptual framework for future research and drug discovery.
Increased vascular permeability is one of the first stages in both physiological and pathological angiogenesis-the generation of new blood vessels from preexisting vasculature. Although this has been hypothesised to be true in physiological angiogenesis, it is clearly a mark of blood vessel growth in disease. Normal, healthy blood vessel growth (physiological angiogenesis) occurs throughout development as well as during tissue repair and growth in adult tissues. Angiogenesis is also seen in a wide variety of diseases, which include all the major causes of mortality in the West-heart disease, cancer, stroke, vascular disease, and diabetes. Much of this angiogenesis is significantly different from normal blood vessel growth and is termed pathological angiogenesis. Angiogenesis is regulated by vascular growth factors, the most notable being the vascular endothelial growth factor family of proteins (VEGF). These act on specific receptors in the vascular system to stimulate new vessel growth by a number of mechanisms. VEGFs also directly stimulate increased vascular permeability to water and large molecular weight proteins and vasodilatation. These two effects result in a large flux of water and macromolecules from the vasculature to the interstitium, often resulting in oedema. This review will outline the mechanisms by which VEGFs do this and discuss some of the difficulties in interpreting data from VEGF studies due to the conflicting and synergistic effects of these actions.
The Katherine Region Diabetic retinopathy Study (KRDRS) was carried out in the Lower Top End of the Northern Territory of Australia between 1993 and 1996 as part of the Northern Territory Eye Health Program. It investigated diabetic eye conditions and their determinants in the Australian Aboriginal population of the region.
The KRDRS was comprised of two cross-sectional surveys, in 1993 and in 1996, and involved a total of 477 subjects with diabetes. Ninety-six subjects were seen in both surveys and met the criteria for inclusion in the longitudinal study. Each subject underwent a general eye examination and retinal photography.
The annual incidence rates of retinopathy were 5.6% (95% CI 3.0-10.0%) and 4.2% (95% CI 2.5-7.0%) in subjects and eyes, respectively. This compares with 8% (in subjects) of the overall Australian diabetic population found in the Newcastle Study of Diabetic Retinopathy. However, each year 1.2% of subjects (95% CI 0.2-3.8%) and 1.3% of eyes (95% CI 0.2-4.5%) with no pre-existing retinopathy developed vision-threatening retinopathy. The respective findings for maculopathy were 2.2% (95% CI 0.7-4.6%) and 1.7% (95% CI 0.7-3.2%), and for clinically significant macula oedema (CSME) 1.1% (95% CI 0.2-3.1%) and 0.9% (95% CI 0.3-2.2%). The annual incidence of CSME in those with no maculopathy when first seen was 1.1% (95% CI 0.2-3.3%) and 0.9% (95% CI 0.3-2.2%) in subjects and eyes, respectively. The annual progression to CSME in those with maculopathy was 4.8% (95% CI 0.1-26.5%) and 6.1% (0.7-21.9%) in subjects and eyes, respectively.
Results of the KRDRS show that despite a lower overall incidence of diabetic retinopathy among Aboriginal diabetics compared to the general Australian diabetic population, there are important reasons to consider Aboriginal diabetics at special risk. These reasons include the highest reported incidence of vision-threatening retinopathy in Australia, one of the highest ever reported incidences of CSME in the world and the likelihood that the severity of the problem may be underestimated because of the relatively short observation time and the low average time since diagnosis. It is also acknowledged that the small numbers in the study limit our ability to reliably detect progression between subsets of the population and much larger studies are required to make statistically significant comparisons.
Diabetic retinopathy has been an important cause of blindness in young and middle age adults in the United States. Epidemiologic studies have quantitated the risk and have described potentially causal factors associated with many ocular complications of diabetes and other facets of this disease. A review of recent advances in diagnosis, treatment, temporal trends, and health care for diabetic retinopathy was conducted. Since the early 1980's, there have been studies of the variability of diabetic retinopathy in populations around the world and subpopulations in the United States which have demonstrated the high prevalences and incidences of this condition. Observational studies and clinical trials have documented the importance of glycemic and blood pressure control in the development and progression of this disease. There are some differences in the importance of confounders in different populations. Epidemiologic data have helped understand the importance of health care and health education in prevention and treatment of this condition. Observational studies have documented the importance of this disease on quality of life. Although there have been advances in understanding the distribution, causes, and severity of diabetic retinopathy, this is ever changing and requires continued monitoring. This is important because the increasing burden of diabetes will place a greater burden on the population and the medical care systems that will be caring for them.
- P Mitchell
- F Bandello
- U Schmidt-Erfurth
- Ge Lang
- P Massin
- Ro Schlingemann
Mitchell P, Bandello F, Schmidt-Erfurth U, Lang GE, Massin P, Schlingemann RO, et
al. The RESTORE Study. Ophthalmology 2011;118:11–1.
Power in the phenotypic extremes: a simulation study of power in discovery and replication of Accepted Article This article is protected by copyright. All rights reserved. rare variants
- Lt Guey
- J Kravic
- O Melander
- Np Burtt
- Jm Laramie
- V Lyssenko
Guey LT, Kravic J, Melander O, Burtt NP, Laramie JM, Lyssenko V, et al. Power in
the phenotypic extremes: a simulation study of power in discovery and replication of
Accepted Article
This article is protected by copyright. All rights reserved.
rare variants. Genet Epidemiol 2011;35:236-46.
Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) Study Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulindependent diabetes mellitus. The Diabetes Control and Complications Trial Research Group
Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and
Complications (DCCT/EDIC) Study Research Group. The effect of intensive treatment
of diabetes on the development and progression of long-term complications in insulindependent diabetes mellitus. The Diabetes Control and Complications Trial Research
Group. N. Engl. J. Med. 1993;329:977–86.
Grading diabetic retinopathy from stereoscopic color fundus photographs-an extension of the modified Airlie House classification. ETDRS report number 10. Early Treatment Diabetic Retinopathy Study Research Group
- Er Group
Group ER. Grading diabetic retinopathy from stereoscopic color fundus photographs-an extension of the modified Airlie House classification. ETDRS report number 10.
Early Treatment Diabetic Retinopathy Study Research Group. Ophthalmology
1991;98:786–806.