Molecular Studies of TCF4 Gene and Correlation with Late-Onset Fuchs Endothelial Corneal Dystrophy in the Greek Population: A Novel Cost-Effective Diagnostic Algorithm

Late-onset Fuchs endothelial corneal dystrophy (FECD) is a hereditary, progressive, bilateral and irreversible disorder that is characterized by thickening of Descemet’s membrane, microscopic collagenous protuberances known as guttae, and accelerated loss of corneal endothelial cells. Patients initially complain of blurred vision, and as the disease progresses, painful epithelial edema develops. Untreated cases of FECD often result in blindness, and then, the only treatment is corneal transplantation. DNA polymorphisms in many genes have been implicated, among them TCF4 on chromosome 18q, encoding a transcription factor protein E2-2, which is involved in regulating cellular growth and differentiation in the cornea. In our previous published study, we confirmed the association of an intronic TCF4 SNP (rs613872) with the disease in our population. The purpose of this present study is to further investigate another intronic point of interest in the same gene, the CTG18.1 trinucleotide repeat expansion. DNA was isolated from EDTA blood from a well-ascertained group of 36 Greek patients with FECD (Krachmer scale ≥ 2) and 58 healthy individuals, age- and sex-matched after obtaining their informed consent. STR-PCR and triplet-repeat primed PCR (TP-PCR) were performed, followed by gel electrophoresis and fragment analysis on an ABI SeqStudio genetic analyzer. Our real-time qPCR genotyping method was used for the SNP in the LightCycler (Roche). Statistical analysis of both genetic results was performed with SPSS and SNPStats.