Cornea - ARVO

ARVO 2013 Annual Meeting Abstracts by Scientific Section/Group - Corneaanalyzer and analyzed using GeneMapper software. The distributionof the alleles and Fisher exact test were performed to test the allelicassociations using Plink algorithms.Results: We first examined the expression of TCF4 and our analysessuggest that the TCF4 is expressed in the corneal endothelium. Wenext examined the repeat length in FCD affected individuals andunaffected controls. Our results suggest that majority (212/288) of theFCD patients harbor a single allele within the normal physiologicalrange of the polymorphic repeat with the second allele undetectablewithin our measurable range. In sharp contrast, the second allele wasundetectable in only a small percentage (75/288) of controls subjects.We examined the distribution of these alleles in FCD affectedindividuals and unaffected controls and found that absence of thesecond allele is significantly associated with late-onset FCD.Interestingly, the absence of second allele segregated with diseasephenotype in the two large familial cases of FCD.Conclusions: The tri-nucleotide repeat expansion represents anothermarker that is significantly associated with FCD. We are currentlyinvestigating the possibility that a particular length and/or a specificrange of the expansion may be responsible for the Fuchs CornealDystrophy.Commercial Relationships: S. Amer Riazuddin, None; Briana C.Gapsis, None; Nicholas Katsanis, None; John D. Gottsch, NoneSupport: This study was supported by the National Eye InstituteGrant R01EY016835 (JDG)Program Number: 4725 Poster Board Number: C0108Presentation Time: 11:00 AM - 12:45 PMAn Investigation of Mitochondrial Haplogroups in FuchsEndothelial Corneal DystrophyYi-Ju Li 1, 2 , Mollie A. Minear 2 , Jacqueline Rimmler 2 , ElmerBalajonda 3 , Michael A. Hauser 2 , R Rand Allingham 3 , Gordon K.Klintworth 3, 4 , Simon G. Gregory 2 , Natalie A. Afshari 5, 3 .1 Biostatistics and Bioinformatics, Duke University Medical Center,Durham, NC; 2 Center for Human Genetics, Medicine, DukeUniversity Medical Center, Durham, NC; 3 Duke University EyeCenter, Duke University Medical Center, Durham, NC; 4 Pathology,Duke University Medical Center, Durham, NC; 5 Shiley Eye Center,University of California San Diego, San Diego, CA.Purpose: To investigate whether European mitochondrial DNA(mtDNA) haplogroups contribute to the susceptibility of Fuchsendothelial corneal dystrophy (FECD). Oxidative stress has beenimplicated in the pathogenesis of FECD, which suggests the potentialrole of mitochondria in FECD. Although mtDNA haplogroups havebeen well-established for each ethnicity, no studies have examinedthe mtDNA variation in FECD.Methods: 529 patients with FECD and 463 controls, all Caucasians,were studied. All FECD patients had guttata grading ≥ 2 by modifiedKrachmer. Controls had a normal corneal exam and age at theenrollment ≥ 50. Nine common European mtDNA haplogroups werepredefined by 10 single nucleotide polymorphisms (SNPs) in thecoding and control regions of the mtDNA genome. We genotypedthese 10 SNPs using custom-designed TaqMan® allelicdiscrimination assays. A logistic regression model with age andgender as covariates was used to test each mtDNA SNP andhaplogroup using the full dataset, and also in a subset of highergraded FECD cases [Grade3+] (grade ≥ 3, N=457). For thehaplogroup analysis, we compared each haplogroup to the mostcommon European haplogroup H. Secondary analyses wereconducted to investigate the interaction between haplogroups and theSNP rs613872 in TCF4, a known risk variant for FECD, and betweenhaplogroup and current smoking status. Since only limited smokingstatus data were available in cases (N=234), a case-only model wasapplied.Results: Three SNPs (rs3021089, rs2853826, and rs34301918)showed nominal significance in both full dataset (min p=0.05) andGrade3+ subset (min p=0.03). On average, 39.7% of subjects havehaplogroup H. Subjects with haplogroup I (3.53%) showedsignificant decrease in risk of FECD comparing to those withhaplogroup H in both full (p=0.024, odds ratio [OR]=0.42, 95%confidence interval [CI] 0.20-0.89) and Grade3+ (p=0.017, OR=0.37,95%CI=0.16-0.84) datasets. None of the mtDNA SNPs andhaplogroups interact with rs613872 in TCF4 (min p=0.26), or withcurrent smoking status (min p=0.08).Conclusions: Our data show that mtDNA haplogroup I confers asignificant protective effect on FECD risk. . We found that the role ofTCF4 in FECD is independent to the mtDNA haplogroup. While nosignificant results were obtained for smoking status, more data areneeded to confirm the current finding. Our study presents animportant step in understanding the effect of mtDNA in FECD.Commercial Relationships: Yi-Ju Li, None; Mollie A. Minear,None; Jacqueline Rimmler, None; Elmer Balajonda, None;Michael A. Hauser, None; R Rand Allingham, New World Medical(C); Gordon K. Klintworth, None; Simon G. Gregory, None;Natalie A. Afshari, NoneSupport: EY016514Program Number: 4726 Poster Board Number: C0109Presentation Time: 11:00 AM - 12:45 PMImpaired mitochondrial membrane potential in Fuchsendothelial corneal dystrophyCecily E. Hamill 1, 2 , Thore Schmedt 1, 2 , Yuming Chen 1, 2 , Ula V.Jurkunas 1, 2 . 1 Massachusetts Eye and Ear Infirmary, Boston, MA;2 Schepens Eye Research Institute, Boston, MA.Purpose: Fuchs Endothelial Corneal Dystrophy (FECD) causesendothelial cell loss via apoptosis and possibly loss of mitochondrialfunction. The purpose of this study was to compare the alterations inmitochondrial membrane potential (MMP) in response to proapoptoticagent straurosporine (STS), between normal endotheliumand FECD-affected endothelial cells.Methods: Normal and FECD endothelial cell lines (HCECi andFECDi, respectively) were exposed to a dose of STS between 0.1 and5.0 µM. Caspase-3 activity was measured using rhodamine 110 bis-(N-CBZ-L-aspartyl-L-glutamyl-L-valyl-L-aspartic acid amide). Withincreasing caspase 3 activity, there is increased fluorescence asmeasured on a plate reader. Mitochondrial damage was assessed bymeasuring uptake of JC-1 (5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcar-bocyanine iodide), which accumulates innegatively charged healthy mitochondria to form aggregates that emitred fluorescence at 590 nm. When MMP is lost, the dye does notaccumulate in the mitochondria and emits green fluorescence at 530nm. The fluorescence was measured on a plate reader, and the ratio ofred to green was calculated. The decrease in the fluorescence ratiofrom baseline indicates a decline in MMP, thus mitochondrialdamage.Results: Initially, corneal endothelial cells were exposed to STS,which caused an increase in capase-3 activity (p=0.005, ANOVA).Likewise, STS caused a decrease in fluorescence ratio in a dosedependent manner in HCECi (p=0.03, ANOVA) and FECDi (p=0.02,ANOVA). When compared to HCECi, FECDi showed a 3-folddecrease in fluorescence ratio at baseline (p=0.001) and after 1.0 µMexposure to STS (p=0.02). There was a 2.5-fold decrease influorescence ratio after STS exposure of 0.1 µM (p=0.01), 0.5 µM(p=0.02), and 5.0 µM (p=0.03) in FECDi as compared to HCECi.Conclusions: STS-induced apoptosis correlated with loss of MMP incorneal endothelium. Lower MMP in FECDi as compared to HCECi©2013, Copyright by the Association for Research in Vision and Ophthalmology, Inc., all rights reserved. Go to iovs.org to access the version of record. For permissionto reproduce any abstract, contact the ARVO Office at arvo@arvo.org.