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Genome-wide linkage scan in fuchs endothelial corneal dystrophy.

ABSTRACT: To perform a genome-wide linkage screen with a single-nucleotide polymorphism (SNP) linkage panel to identify regions of genetic linkage in Fuchs endothelial corneal dystrophy (FECD) and to analyze affected individuals for mutations in the COL8A2 gene.Ninety-two individuals from 22 families with FECD were identified from our multiplex FECD family cohort. A genome-wide linkage scan was performed using an SNP linkage panel. Parametric two-point linkage analyses were calculated and nonparametric multipoint linkage analyses were performed on chromosomes with two-point LOD scores (HLOD) > 1.0. All affected individuals were analyzed for the two previously reported FECD mutations in the COL8A2 gene (L450W and Q455K).The genome-wide analysis identified five regions with linkage signals from all analyses on chromosomes 1, 7, 15, 17, and X. The highest two-point HLODs were found on the long arm of chromosome 15 with an HLOD of 3.26 for the recessive model and 2.48 for the dominant model. Multipoint linkage analysis also identified a linkage peak on the long arm of chromosome 15 with a LOD > 1. The region of linkage on chromosome 1p, driven by two multigenerational FECD families with a two-point LOD > 2, was adjacent to the previously identified COL8A2 gene; however, the two reported mutations in COL8A2 were not identified in any of the 56 affected individuals in the 92 samples tested.Genome-wide linkage analysis was used to identify potential linkage regions on chromosomes 1, 7, 15, 17, and X for FECD. The previously reported mutations in the COL8A2 gene were not found in the 92 samples tested.

SUBMITTER: Afshari NA

PROVIDER: S-EPMC2712757 | biostudies-literature | 2009 Mar

REPOSITORIES: biostudies-literature

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Genome-wide linkage scan in fuchs endothelial corneal dystrophy.

Afshari Natalie A NA Li Yi-Ju YJ Pericak-Vance Margaret A MA Gregory Simon S Klintworth Gordon K GK

Investigative ophthalmology & visual science 20080523 3

<h4>Purpose</h4>To perform a genome-wide linkage screen with a single-nucleotide polymorphism (SNP) linkage panel to identify regions of genetic linkage in Fuchs endothelial corneal dystrophy (FECD) and to analyze affected individuals for mutations in the COL8A2 gene.<h4>Methods</h4>Ninety-two individuals from 22 families with FECD were identified from our multiplex FECD family cohort. A genome-wide linkage scan was performed using an SNP linkage panel. Parametric two-point linkage analyses were ...[more]

PMID: 18502986

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Project description:Purpose To develop a model to predict corneal improvement after Descemet membrane endothelial keratoplasty (DMEK) for Fuchs endothelial corneal dystrophy (FECD) from Scheimpflug tomography. Design Cross-sectional study. Participants Forty-eight eyes (derivation group) and 45 eyes (validation group) with a range of severity of FECD undergoing DMEK. Methods Scheimpflug images were obtained before and after DMEK. Before DMEK, pachymetry map and posterior elevation map patterns were quantified by a special image analysis program measuring tomographic features of edema (loss of regular isopachs, displacement of the thinnest point of the cornea, posterior surface depression). Image-derived novel parameters were combined with instrument-derived parameters, and the relative influences of parameters associated with the change in central corneal thickness (CCT) after DMEK in the derivation group were determined by using a gradient boosting machine learning model. The parameters with highest relative influence were then fit in a linear regression model. The derived model was applied to the validation group. Correlations and agreement were assessed between predicted and observed changes in CCT. Main Outcome Measures Predictive power (R2) and mean difference between predicted and observed change in CCT. Results The gradient boosting machine model identified 4 novel parameters of isopach circularity and eccentricity and 1 instrument-derived parameter (posterior surface radius); preoperative CCT was a poor predictor. In the derivation group, the model strongly predicted the change in CCT after DMEK (R2 = 0.80; 95% confidence interval [CI], 0.71–0.89) and the mean difference between predicted and observed change was, by definition, 0 μm. When the same 5 parameters were fit to the validation group, the model performed very highly (R2 = 0.89; 95% CI, 0.84–0.94). When the coefficient estimates from the derivation model were used to predict the change in CCT in the validation group, the predictive power was also high (R2 = 0.78; 95% CI, 0.68–0.88), and the mean difference was 4 μm (predicted minus observed). Conclusions Scheimpflug tomography maps of corneas with FECD can predict the improvement in CCT after DMEK, independent of preoperative corneal thickness measurement. The model could be applied in clinical practice or for clinical research of FECD.

Project description:Fuchs’ endothelial corneal dystrophy (FECD) is a progressive vision impairing disease caused by thickening of Descemet’s membrane and gradual degeneration and loss of corneal endothelial cells. The aim of this study was to identify differentially expressed genes between FECD-affected and unaffected corneal endothelium to gain insight into the pathophysiological mechanisms underlying this disease. Microarray gene expression analysis was performed on total RNA from FECD-affected and unaffected corneal endothelium-Descemet’s membrane (CE-DM) specimens using the Illumina HumanHT-12 v3.0 expression array. RNA from pools of FECD-affected (n=3 per pool) and individual unaffected (n=3) specimens was used for comparison. Altered expression of a sub-set of differentially expressed genes was validated by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) in independent specimens. Bioinformatics analysis was performed using InnateDB to reveal functional relationships among the differentially expressed genes and molecular pathways involved in the disease. A total of 16,513 genes were found expressed in the corneal endothelium of which 142 genes were differentially expressed between FECD-affected and unaffected endothelium (log2 fold-change ≥1.5, corrected p-value ≤0.05). Most of the genes were up-regulated (126) and a small proportion down-regulated (16) in affected corneal endothelium. Of the twelve genes prioritised for validation, differential expression of 10 genes, including those ranked 57th and 81st by significance validated by qRT-PCR (8 up-regulated and 2 downregulated, corrected p ≤0.05), one gene showed a trend for up-regulation in affected endothelium, consistent with the microarray analysis and another was up-regulated in an independent study indicating robustness of the differential expression dataset. Bioinformatic analysis revealed significant over-representation of differentially expressed genes in extracellular matrix reorganisation, cellular remodelling, immune response, and inflammation. Network analysis showed functional inter-relatedness of the majority of the dysregulated genes and revealed known direct functional relationships between 20 of the genes; many of these genes have roles in macrophage differentiation, phagocytosis and inflammation. This is the second report of microarray gene expression analysis in FECD. This study revealed a set of highly dysregulated genes in the corneal endothelium in FECD. More than a third of the dysregulated genes in the disease have been discovered for the first time and thus are novel. The dysregulated genes strongly suggest the presence of phagocytic cells, most likely immune cells, and inflammation in corneal endothelium in the disease. This study provides a molecular framework for delineating the mechanisms underlying these cellular processes in FECD.

Dataset Information

Genome-wide linkage scan in fuchs endothelial corneal dystrophy.

Publications

Genome-wide linkage scan in fuchs endothelial corneal dystrophy.

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