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Sina Vahedi, Shivakumar Vasanth, S Amer Riazuddin, John Gottsch, Allen O Eghrari; CTG18.1 trinucleotride repeat expansion in African-Americans with Fuchs Corneal Dystrophy. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1439. doi: https://doi.org/.
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Data suggest differences in corneal thickness between African-Americans and Caucasians with Fuchs Dystrophy. Differences in genotype across populations have not been fully explored.
Patients with FCD were diagnosed clinically through slit-lamp biomicroscopy and invited to enroll in a longitudinal cohort. Demographic information, including race and gender, were provided by patients. Participants provided a blood sample from which we extracted genomic DNA. The CTG18.1 trinucleotide repeat length was determined using a two-step, triplet repeat primed PCR (TP-PCR) protocol. Expansion was defined as >40 CTG repeats. Fisher exact test was utilized to test for an association between race and repeat expansion.
61 African-Americans and 549 Caucasian patients with Fuchs Corneal Dystrophy enrolled in the longitudinal study and provided clinical and genetic data. Among 61 African-Americans, 21 (34%) demonstrated expansion, of which 1 case was biallelic. In comparison, among 549 Caucasians, 343 (62.5%) demonstrated expansion; 3.8% of expanded cases were biallelic. A strong association existed between race and repeat expansion (p= 3.0 x 10^-5). The proportion of bilallelic expansion was not different between groups (P=0.57).
A strong association exists between CTG18.1 allele expansion and race in FCD patients. Further study is required to clarify its contribution to distinctions in phenotype across races.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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