SLC2A1 Tag SNPs in Greek Patients with Diabetic Retinopathy and Nephropathy.

Backround: Genetic variants are implicated in the development of diabetic retinopathy (DR) and nephropathy (DN). The role of solute carrier family 2-facilitated glucose transporter member 1 (SLC2A1), also known as glucose transporter (GLUT1), on DR and DN remain controversial. OBJECTIVE: Examination of the influence of tag SLC2A1 single-nucleotide polymorphisms (SNPs) on the development of DR and DN during the course of type 2 diabetes mellitus (T2DM). METHODS: A total of 169 patients with DR or DN, 107 uncomplicated T2DM patients, and 315 controls were recruited and genotyped for 14 SLC2A1 tag SNPs. SNPs and haplotypes were tested for associations with microvascular diabetes' complications. RESULTS: rs3768029 TT genotype was associated with a lower risk of DR + DN, compared to the CC wild-type (p = 0.0024). Moreover, CT and TT rs841847 genotypes were associated with a higher risk of DR + DN compared to the CC genotype (p = 0.0028). A common haplotype (GGCCCGCATCAAT) was associated with an increased risk of DR, DN, DR ± DN, and DR + DN phenotypes. Mutational loads of rs3768029, rs3729548, rs841853, and rs841847 were found to influence the development of microvascular complications during the T2DM course. CONCLUSIONS: This study provides evidence that SLC2A1 gene variants might be implicated in the development of T2DM microvascular complications.

Systems biology-based analysis implicates a novel role for vitamin D metabolism in the pathogenesis of age-related macular degeneration.

Vitamin D has been shown to have anti-angiogenic properties and to play a protective role in several types of cancer, including breast, prostate and cutaneous melanoma. Similarly, vitamin D levels have been shown to be protective for risk of a number of conditions, including cardiovascular disease and chronic kidney disease, as well as numerous autoimmune disorders such as multiple sclerosis, inflammatory bowel diseases and type 1 diabetes mellitus. A study performed by Parekh et al. was the first to suggest a role for vitamin D in age-related macular degeneration (AMD) and showed a correlation between reduced serum vitamin D levels and risk for early AMD. Based on this study and the protective role of vitamin D in diseases with similar pathophysiology to AMD, we examined the role of vitamin D in a family-based cohort of 481 sibling pairs. Using extremely phenotypically discordant sibling pairs, initially we evaluated the association of neovascular AMD and vitamin D/sunlight-related epidemiological factors. After controlling for established AMD risk factors, including polymorphisms of the genes encoding complement factor H (CFH) and age-related maculopathy susceptibility 2/HtrA serine peptidase (ARMS2/HTRA1), and smoking history, we found that ultraviolet irradiance was protective for the development of neovascular AMD (p = 0.001). Although evaluation of serum vitamin D levels (25-hydroxyvitamin D [25(OH)D]) was higher in unaffected individuals than in their affected siblings, this finding did not reach statistical significance. Based on the relationship between ultraviolet irradiance and vitamin D production, we employed a candidate gene approach for evaluating common variation in key vitamin D pathway genes (the genes encoding the vitamin D receptor [VDR]; cytochrome P450, family 27, subfamily B, polypeptide 1 [CYP27B1]; cytochrome P450, family 24, subfamily A, polypeptide 1 [CYP24A1]; and CYP27A1) in this same family-based cohort. Initial findings were then validated and replicated in the extended family cohort, an unrelated case-control cohort from central Greece and a prospective nested case-control population from the Nurse's Health Study and Health Professionals Follow-Up Studies, which included patients with all subtypes of AMD for a total of 2,528 individuals. Single point variants in CYP24A1 (the gene encoding the catabolising enzyme of the vitamin D pathway) were demonstrated to influence AMD risk after controlling for smoking history, sex and age in all populations, both separately and, more importantly, in a meta-analysis. This is the first report demonstrating a genetic association between vitamin D metabolism and AMD risk. These findings were also supplemented with expression data from human donor eyes and human retinal cell lines. These data not only extend previous biological studies in the AMD field, but further emphasise common antecedents between several disorders with an inflammatory/immunogenic component such as cardiovascular disease, cancer and AMD.

Blood velocity pulse quantification in the human conjunctival pre-capillary arterioles.

Axial red blood cell velocity pulse was quantified throughout its period by high speed video microcinematography in the human eye. In 30 conjunctival precapillary arterioles (6 to 12 microm in diameter) from 15 healthy humans, axial velocities ranged from 0.4 (the minimum of all the end diastolic values) to 5.84 mm/s (the maximum of all the peak systolic values). With the velocity pulse properly quantified, two parameters can be estimated: (1) the average velocity of the pulse during a cardiac cycle AVV (average velocity value) and (2) the magnitude of the pulsation using Pourcelot's resistive index RI. These parameters are important for the estimation of other hemodynamic parameters such as the average volume flow and the average shear stress. The results of this study revealed that the AVV in the human precapillary arterioles ranged between 0.52 and 3.26 mm/s with a mean value for all microvessels of 1.66 mm/s+/-0.11(SE). The RI ranged between 35.5% and 81.8% with a mean value of 53.1%+/-2.2. Quantitative information was obtained for the first time on the velocity pulse characteristics just before the human capillary bed.

Evaluation of MMP1 and MMP3 gene polymorphisms in exfoliation syndrome and exfoliation glaucoma.

PURPOSE: To investigate possible genetic associations of matrix metalloproteinase-1 (MMP1) and MMP3 gene polymorphisms with exfoliation syndrome (XFS) with (XFS/+G) and without (XFS/-G) glaucoma in a cohort of Greek patients. METHODS: A total of 182 unrelated Greek patients with XFS, including 92 patients with XFS/+G, and 214 unrelated age- and gender-matched controls were enrolled in the study. MMP1 -1607 1G/2G (rs1799750) and MMP3 -1171 5A/6A (rs3025058) polymorphisms were determined using standard PCR/restriction fragment length polymorphism methods. Differences in allele and genotype distributions were analyzed using logistic regression. RESULTS: The distribution of genotypes and alleles in MMP1 and MMP3 polymorphisms was not significantly different between cases with exfoliation syndrome, with or without glaucoma, and controls. However, the allele contrast for the MMP1 variant showed a trend for a significant association with XFS/-G (Odds Ratio=1.47 [1.03-2.10]), since after correction for multiple comparisons, this association was no longer statistically significant. CONCLUSIONS: Our study provided some evidence of a possible role of the MMP1 variant in the development of exfoliation syndrome in Greek patients.

Resolution of macular edema in idiopathic juxtafoveal telangiectasis using PDT.

A 57-year-old woman was treated by photodynamic therapy for macular edema due to idiopathic juxtafoveal telangiectasis (presumed type 1A) without subretinal neovascularization. Initial visual acuity of the treated eye was 20/200 and it improved to 20/40 by 3 months after the photodynamic therapy session. Visual acuity remained stable 32 months after the treatment. Color photographs and fundus fluorescein angiography before and after photodynamic therapy revealed regression of hemorrhages, exudates, and fluorescein leakage. Photodynamic therapy has long-term benefits for the patient with idiopathic juxtafoveal telangiectasis, presumed type 1A, because it can improve visual acuity and macular edema.

Detection of macular photocoagulation scars with confocal infrared reflection imaging.

BACKGROUND AND OBJECTIVE: To study the diagnostic reliability (specificity and sensitivity) of confocal infrared reflection in detecting threshold argon laser photocoagulation scars in the macula. PATIENTS AND METHODS: Fifty-six maculae with diabetic macular edema were evaluated by biomicroscopic slit-lamp fundus examination, digital color fundus photography, digital fundus fluorescein angiography, and digital infrared reflection images. Three examiners evaluated whether the eye had undergone any laser photopexy in the macula. RESULTS: Sensitivity, specificity, and false-positive and false-negative results were calculated for each method. Fluorescein fundus angiography and infrared imaging, although using different approaches, both detect pigment epithelium changes such as laser scars. It seems that both methods are of equal specificity. On the other hand, both biomicroscopic fundus examination and digital color photography showed poor reliability. CONCLUSION: Infrared reflection imaging is an easy, noninvasive method with excellent sensitivity and specificity in detecting photocoagulation scars from previous threshold laser treatment. It may be useful in estimating photocoagulated areas, especially if threshold treatment has been applied.

Volume flow and wall shear stress quantification in the human conjunctival capillaries and post-capillary venules in vivo.

Understanding the mathematical relationships of volume blood flow and wall shear stress with respect to microvessel diameter is necessary for the study of vascular design. Here, for the first time, volume flow and wall shear stress were quantified from axial red blood cell velocity measurements in 104 conjunctival microvessels of 17 normal human volunteers. Measurements were taken with a slit lamp based imaging system from the post capillary side of the bulbar conjunctiva in microvessel diameters ranging from 4 to 24 micrometers. The variation of the velocity profile with diameter was taken into account by using a profile factor function. Volume flow ranged from 5 to 462 pl/s with a mean value of 102 pl/s and gave a second power law best fitting line (r=0.97) deviating significantly from the third power law relation with diameter. The estimated wall shear stress declined hyperbolically (r=0.93) from a maximum of 9.55 N/m(2) at the smallest capillaries, down to a minimum of 0.28 N/m(2) at the higher diameter post capillary venules. The mean wall shear stress value for all microvessels was 1.54 N/m(2).

Metabolic control of diabetes is associated with an improved response of diabetic retinopathy to panretinal photocoagulation.

OBJECTIVE: To study the influence of glycemic control and the presence of microalbuminuria on the initial response to panretinal photocoagulation (PRP) in patients with a high-risk proliferative diabetic retinopathy (PDR). RESEARCH DESIGN AND METHODS: This was a prospective cohort study with a two-by-two factorial design. We used full-scattered PRP to treat 115 eyes of type 2 diabetic patients who have high-risk PDR. HbA1c (A1C) and albumin levels in 24-h urine were constantly monitored during the pre-enrollment, treatment, and posttreatment periods. At a follow-up visit 12 weeks after the last PRP session, the fundus was examined for characteristics of regression from high-risk PDR and the response to PRP was determined to be successful or unsuccessful. The eyes were categorized into four groups based on average A1C levels and the presence or absence of microalbuminuria. The data were analyzed using a logistic regression model. Our statistical analysis determined the probability of achieving a satisfactory response to PRP in association with A1C levels and the presence or absence of microalbuminuria. RESULTS: Of the 115 eyes examined, 65 (56.5%) had a successful initial response to PRP and 50 (43.5%) did not. The probability of a satisfactory response to PRP was related to A1C levels (P < 0.05) but not to microalbuminuria and its interaction with hemoglobin glycosylation (P > or = 0.05). CONCLUSIONS: Low levels of hemoglobin glycosylation (A1C <8%) during the pretreatment, treatment, and posttreatment periods are associated with a regression of proliferative diabetic retinopathy after PRP.

Influence of ROBO1 and RORA on risk of age-related macular degeneration reveals genetically distinct phenotypes in disease pathophysiology.

ROBO1 is a strong candidate gene for age-related macular degeneration (AMD) based upon its location under a linkage peak on chromosome 3p12, its expression pattern, and its purported function in a pathway that includes RORA, a gene previously associated with risk for neovascular AMD. Previously, we observed that expression of ROBO1 and RORA is down-regulated among wet AMD cases, as compared to their unaffected siblings. Thus, we hypothesized that contribution of association signals in ROBO1, and interaction between these two genes may be important for both wet and dry AMD. We evaluated association of 19 single nucleotide polymorphisms (SNPs) in ROBO1 with wet and dry stages of AMD in a sibling cohort and a Greek case-control cohort containing 491 wet AMD cases, 174 dry AMD cases and 411 controls. Association signals and interaction results were replicated in an independent prospective cohort (1070 controls, 164 wet AMD cases, 293 dry AMD cases). The most significantly associated ROBO1 SNPs were rs1387665 under an additive model (meta P = 0.028) for wet AMD and rs9309833 under a recessive model (meta P = 6 × 10(-4)) for dry AMD. Further analyses revealed interaction between ROBO1 rs9309833 and RORA rs8034864 for both wet and dry AMD (interaction P<0.05). These studies were further supported by whole transcriptome expression profile studies from 66 human donor eyes and chromatin immunoprecipitation assays from mouse retinas. These findings suggest that distinct ROBO1 variants may influence the risk of wet and dry AMD, and the effects of ROBO1 on AMD risk may be modulated by RORA variants.

Neovascular glaucoma as a first clinical manifestation of multiple sclerosis.

PURPOSE: To report a case with neovascular glaucoma caused by severe occlusive retinal vasculitis, as a first clinical manifestation of multiple sclerosis (MS). METHODS: Examination on an otherwise healthy 45-year-old man presenting with blurred vision in his right eye revealed bilateral iris neovascularization, right eye neovascular glaucoma, and bilateral retinal neovascularization caused by vasculitis. Thorough systemic investigation indicated by an ophthalmologist showed nothing else other than typical to MS imaging and spinal tap findings. The patient received bilateral treatment with panretinal photocoagulation and intravitreal bevacizumab (Avastin, Genentech, Inc., South San Francisco, CA) injection in the right eye. RESULTS: Ten months later, the patient was found with paraclinical neurologic findings completing the diagnostic criteria of definite laboratory supported MS. After the 3 years that followed, the ocular disease was eliminated, and the underlying disease remains clinically silent. CONCLUSION: As illustrated by our case, MS should be considered as an underlying disorder in patients with neovascular glaucoma caused by occlusive retinal vasculitis.

Convergence of linkage, gene expression and association data demonstrates the influence of the RAR-related orphan receptor alpha (RORA) gene on neovascular AMD: a systems biology based approach.

To identify novel genes and pathways associated with AMD, we performed microarray gene expression and linkage analysis which implicated the candidate gene, retinoic acid receptor-related orphan receptor alpha (RORA, 15q). Subsequent genotyping of 159 RORA single nucleotide polymorphisms (SNPs) in a family-based cohort, followed by replication in an unrelated case-control cohort, demonstrated that SNPs and haplotypes located in intron 1 were significantly associated with neovascular AMD risk in both cohorts. This is the first report demonstrating a possible role for RORA, a receptor for cholesterol, in the pathophysiology of AMD. Moreover, we found a significant interaction between RORA and the ARMS2/HTRA1 locus suggesting a novel pathway underlying AMD pathophysiology.

Ocular disorders as the prevailing manifestations of antiphospholipid syndrome: a case series.

INTRODUCTION: Antiphospholipid syndrome is an autoimmune disorder characterized by either a history of vascular thrombosis (one or more clinical episodes of arterial, venous, or small vessel thrombosis in any tissue or organ) or pregnancy morbidity in association with the presence of antiphospholipid antibodies. The systemic features of the syndrome are characterized by large variability depending on the affected organ(s). Among them, neurological and behavioural disturbances, dermatological features as livedo reticularis and renal, ocular, liver or valvular heart manifestations have been reported in antiphospholipid syndrome patients. However, studies on the frequency and clinical presentation of the ocular manifestations as the prevailing (first) sign of antiphospholipid syndrome in patients suffering from "unexplained" ocular disease are missing. Herein, we present three cases suffering from unexplained ocular disease as first manifestation of antiphospholipid syndrome. CASE PRESENTATION: All the three patients were referred to our department because of unexplained ocular features from the anterior or posterior segment and unexplained neuro-ophthalmologic symptoms. The first patient had bilateral retinal occlusive disease, the second and the third patient had unilateral nonarteritic anterior ischemic optic neuropathy with macular oedema. Moderate to high levels of antiphospholipid antibodies were detected in all of them at baseline as well as 6 to 12 weeks after initial testing confirming the presence of antiphospholipid antibodies. Anticoagulant treatment with acenocoumarol was instituted resulting in stabilization and/or improvement of ocular signs in all of them. CONCLUSION: Due to the important diagnostic and therapeutic implications of antiphospholipid syndrome, the possibility of ocular features as the first clinical manifestation of antiphospholipid syndrome should be kept in mind of the physicians particularly in patients with no evident risk factors for ocular disease. In this case, prompt anticoagulant treatment and close follow-up seem to be essential for vision salvation and stabilization.