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Ahmed Z Soliman, Xin Gong, Imran Hussain, Chao Xing, Vinod V Mootha; CTG18.1 Trinucleotide Repeat Expansion of TCF4 Gene in Fuchs’ Endothelial Corneal Dystrophy. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1005.
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Background: Fuchs’ endothelial corneal dystrophy (FECD) is a bilateral, progressive disorder of the endothelium that can result in corneal edema and loss of vision. It is the leading indication for corneal transplantation in the United States and is estimated to affect 4% of the population over the age of forty in this country. Previous studies have documented that the expanded TCF4 CTG 18.1 allele confers a significant risk for FECD. Purpose: To compare the demographics, severity of FECD, and likelihood of undergoing keratoplasty in TCF4 CTG 18.1 expansion positive and negative cases.
The trinucleotide repeat polymorphism CTG18.1 was genotyped using a combination of short tandem repeat assay and triplet repeat primed PCR assay. CTG repeat length of ≥ 40 was classified as an expanded CTG18.1 allele. Grading the clinical severity of FECD was done using a modified Krachmer scale. A severity score was created for each patient using the sum of the grades from both eyes. Association of the expanded TCF4 CTG 18.1 allele with the severity of FECD and the likelihood of requiring keratoplasty were evaluated.
240 subjects with FECD were recruited. Over two thirds of patients were females (N=165, 68.8%) and the majority were Caucasians (N=218, 90.8%). Patients with expansion positive FECD (N=158, 65.8%) had a mean age of 68.32 years ± 13.88 (mean ± SD), 63.9% were females (N=101) and 98.1% were Caucasians (N=155). Patients with expansion negative FECD (N=82, 34.2%) had a mean age of 63.45 years ± 13.18 (mean ± SD), 78.0% were females (N=64) and 76.8% were Caucasians (N=63). Compared with the expansion negative FECD subgroup, patients with the expanded CTG18.1 allele had increased clinical severity of FECD (P<0.0001) and were more likely to undergo keratoplasty (p=0.0004). No difference was found in the prevalence of the expanded allele among familial vs. presumed sporadic cases (p=0.1704).
The expanded TCF4 CTG 18.1 allele confers significant risk for increased clinical severity of FECD and the likelihood of requiring keratoplasty for visual rehabilitation. The presence of the expanded CTG 18.1 allele was not significantly different among familial and presumed sporadic cases in this cohort.
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