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V. J. Correa-Gomez, B. Buentello-Volante, C. SantaCruz, J. C. Zenteno; SNPs Homozygosity Mapping in a Family With a Potentially Novel Form of Endothelial Corneal Dystrophy. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4640.
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© ARVO (1962-2015); The Authors (2016-present)
Propose: The term posterior corneal dystrophies comprise a heterogeneous group of disorders that include Fuchs corneal dystrophy (FECD), posterior polymorphous corneal dystrophy (PPCD), congenital hereditary endothelial corneal dystrophy (CHED) and X-linked endothelial corneal dystrophy (XECD). These diseases are characterized by abnormalities of the corneal endothelium and Descemet membrane. In most of these disorders, a defective active fluid transport by the corneal endothelium causes excessive edema of the corneal stroma and this impairs the transparency of the cornea and reduces visual acuity. The aim of this work is to present the clinical and genetic analysis of a family with two affected patients suffering from an atypical type of Endothelial Corneal Dystrophy.
Two affected sibs, aged 49 and 43 years, underwent a complete ophthalmological examination. A Genome wide search for homozygosity regions in DNA from the two affected subjects and from one unaffected daughter was performed using the Affymetrix 250k Nsp microarray. Analysis of relevant homozygosity regions was done using the HomozygosityMapper software. Identification of candidate genes within significant homozygosity regions was performed with GeneDistiller software.
A homogeneous bilateral corneal phenotype was observed in both affected sibs. This included normal epithelium, stromal edema, endothelial changes, and pigment dusting on endothelium. No corneal endothelial guttata or folds, a hallmark of FCED, were evident in both patients. SNPs homozygosity mapping identified a 45 MB homozygote region at chromosome 4q27-q32, only in DNA from both affected sibs. No obvious candidate genes for the disorder were identified within this interval using GeneDistiller.
The corneal phenotype observed in the two affected sibs was not easily classifiable as part of the group of posterior corneal dystrophies. The absence of corneal guttae and the autosomal recessive transmission of the disease argue against a FECD diagnosis. Our results suggest the existence of a novel locus for endothelial dystrophy at 4q27-q32. Analysis of additional unaffected relatives from this family will help to refine the candidate loci.
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