Oxidative stress refers to cellular or molecular damage caused by reactive oxygen species, which especially occurs in age-related conditions as a result of an imbalance between the production of reactive oxygen species and the antioxidant defense response. Dry age-related macular degeneration (AMD) and exfoliation syndrome (XFS) are two common and complex age-related conditions that can cause irreversible vision loss. Two subtypes of AMD, which is the leading cause of blindness in the Western world, exist: the most prevalent dry type and the most severe wet type. Early dry AMD is characterized by formation of drusen, which are sub-retinal deposits, in the macular area and may progress to geographic atrophy with more dramatic manifestation. XFS is a systemic disorder of the extracellular matrix characterized by the accumulation of elastic fibrils that leads, in most cases, to glaucoma development with progressive and irreversible vision loss. Due to the aging population, the prevalence of these already-widespread conditions is increasing and is resulting in significant economic and psychological costs for individuals and for society. The exact composition of the abnormal drusen and XFS material as well as the mechanisms responsible for their production and accumulation still remain elusive, and consequently treatment for both diseases is lacking. However, recent epidemiologic, genetic and molecular studies support a major role for oxidative stress in both dry AMD and XFS development. Understanding the early molecular events in their pathogenesis and the exact role of oxidative stress may provide novel opportunities for therapeutic intervention for the prevention of progression to advanced disease.

BackgroundAge-related macular degeneration (AMD) is a multifactorial degenerative ocular disease that leads to loss of central vision. Functional gene polymorphisms have already been associated with the disease (for example, ARMS2 A69S, rs10490924).AimThe goal of our study was to verify the correlation of the aforementioned ARMS2 variation with the disease, to examine, for the first time, the role of the CD14 C260T variation (rs2569190), and to investigate the association of two TLR4 polymorphisms (Asp299Gly or rs4986790 and Thr399Ile or rs4986791) in a Greek population with the wet form of AMD.Patients and methodsGenomic DNAs were isolated from blood samples of 103 healthy controls and 120 Greek patients with wet AMD who were age- and sex-matched, and all of whom were clinically evaluated. For the genotyping of all selected polymorphisms, polymerase chain reaction–restriction fragment length polymorphism analysis was performed.Results and conclusionsThis study confirmed the association between the ARMS2 variation and AMD, detecting the T risk allele in a significantly higher frequency in the patient group, compared with the control subjects (45% vs 29.13%, P<0.001, odds ratio [OR] 1.99, confidence interval 1.34–2.95). For the CD14 polymorphism, no statistically significant correlation was observed. As for the TLR4 polymorphisms, the percentage of heterozygotes increased from 2.9% to 11.7% in the patient population for Asp299Gly and from 1.9% to 10% for the Thr399Ile polymorphism (ORs 4.40 [P=0.01] and 5.61 [P=0.0088], respectively). Although our ARMS2 and CD14 results provided definite conclusions, the role of innate immunity TLR4 gene awaits further investigation in larger AMD populations with more clinical data collected on past microbial infections.

The present study confirmed the association between CFH Y402H SNP and wet AMD in the Greek population (OR=1.77, p=0.002). FCGR2A H131R polymorphism was investigated for the first time in this present study for possible correlation with wet AMD and a statistically significant association was detected (OR=1.74, p=0.006), that awaits further confirmation in a larger set of samples.

ΣΚΟΠΟΣ : Αξιολόγηση της συμβολής των πολυμορφισμών στα γονίδια CFH ,ARMS2, APOE ,FCGR2A στην προδιάθεση για εκδήλωση ΗΕΩ (ηλικιακής εκφύλισης ωχράς κηλίδας) στον Ελληνικό πληθυσμό.ΜΕΘΟΔΟΛΟΓΙΑ : Η απομόνωση του DNA πραγματοποιήθηκε με στήλες φυγοκέντρησης QIAamp,από αίμα ασθενών με ΗΕΩ και υγιών (κατόπιν οφθαλμολογικού ελέγχου). Για τη γονοτύπωση των πολυμορφισμών στα γονίδια ARMS2 και APOE χρησιμοποιήθηκε η τεχνική PCR-RFLP (Polymerase Chain Reaction- Restriction Fragment Length Polymorphism) και επιπλέον αναπτύχθηκε νέα μεθοδολογία με PCR πραγματικού χρόνου και ανάλυση καμπύλων τήξης για τον πολυμορφισμό Y402H του γονιδίου CFH και H131R του FCGR2A. Ακολούθησε στατιστική ανάλυση με προγράμματα SNPStats και SPSS .ΑΠΟΤΕΛΕΣΜΑΤΑ : Πραγματοποιήθηκε αρχικά έλεγχος για συσχετισμό των 4 γονιδίων αυτών με την ΗΕΩ σε δείγματα αίματος 27 πασχόντων και 34 υγιών εθελοντών αναδεικνύοντας μια ισχυρή συσχέτηση της νόσου με τους Υ402Η στο CFH (OR=2,68) και H131R στο FCGR2A (OR=3.17) ενώ δεν υπήρξε στατιστικά σημαντική συσχέτηση της νόσου με τους πολυμορφισμούς σε ARMS2 και ApoE . Σε δεύτερο χρόνο μελετήθηκε σε δείγματα 120 ασθενών και 103 υγιών η συμβολή των πολυμορφισμών στα CFH και FCGR2A για εκδήλωση ΗΕΩ όπου φάνηκε να υπάρχει στατιστικά σημαντική συσχέτηση με OR=1,77 και 1,74 αντίστοιχα. ΣΥΜΠΕΡΑΣΜΑ : Η μελέτη για πρώτη φορά της συσχέτισης της ΗΕΩ με τον πολυμορφισμό Η131R απέδωσε σημαντικά αποτελέσματα, προτείνοντας ισχυρή συσχέτιση και μεγάλο σχετικό κίνδυνο για τους φορείς της μετάλλαξης.