GLAUGEN-Methylation in POAG

This is a case-control study of Primary Open Angle Glaucoma (POAG). POAG is a progressive optic neuropathy that eventually leads to blindness. More than 30 million people worldwide have Primary Open Angle Glaucoma (POAG), of which greater than 3 million are blind. Gene expression changes in the retina have been observed for POAG. Several recent studies, including the GLAUGEN (Glaucoma Gene Environment) initiative have used GWAS to identify correlative regions of the genome. Despite this, the genetic basis of Glaucoma is not well understood. Epigenetic variation may account for low heritability and environmental effects on human disease. Despite the significant advances being made in understanding the role of epigenetics in gene regulation in other fields, little is known about the relationship between DNA methylation patterns, retinal gene expression, and retinal disease. The goal of this study is to identify differentially methylated regions in the peripheral blood of patients with POAG. The case identification is as per the GLAUGEN description: Cases and controls were recruited from ophthalmology clinics and were examined by ophthalmologists. For cases the clinical exam included intraocular pressure measurements, optic nerve assessment and visual field evaluation. Controls had no family history of glaucoma, normal intraocular pressure and normal optic nerves. POAG and control samples come from Massachusetts Eye and Ear Infirmary (MEEI). These samples were collected and genotyped as part of the GLAUGEN study. From the MEEI, 50 patients were selected from POAG pedigrees, to include all the probands genotyped by CIDR and are currently undergoing exome sequencing, and to include additional genotyped probands who belong to pedigrees of sufficient size and structure that parent of origin effects could be evaluated. Additional individual-level phenotype and genotype data may be obtained through the authorized access portal of phs000308 (Geneva - Glaugen GWAS Study).]]>
Unrelated individuals were selected as cases or controls for this study. All subjects consented to sharing their samples. Both cases and controls were examined by a trained ophthalmologist. All cases and controls were at least 35 years old and all were Caucasian. Cases had either reproducible visual field loss in at least one eye in a nerve fiber layer distribution on two independent reliable visual fields, or a vertical cup to disc ratio (CDR) of at least 0.8 in the one eye. For automated visual fields, a reliable visual field was defined by fixation loss ≤ 33%, false positive rate ≤ 20% and false negative rate ≤ 20%. Intraocular pressure was noted for all cases, but was not part of the case definition. Exclusion criteria for cases included: myopia of −8D or greater, clinical findings suggestive of secondary glaucomas (pigment dispersion, exfoliation and anterior segment dysgenesis) and narrow filtration angles. Controls did not have a family history of glaucoma, had intraocular pressures less than 21 mmHg, had vertical cup to disc ratios of less than 0.7 and CDR asymmetry of less than 0.2. Controls also did not have any evidence of secondary glaucomas or narrow filtration angles. ]]>
Samples in this study were originally collected as part of the GLAUGEN consortium. Samples collected at MEEI have been previously genotyped using the ILLUMINA Human660W-Quad platform.]]>