CTG REPEAT EXPANSION IN THE TCF4 GENE IN THAI PATIENTS WITH FECD

Abstract

Fuchs Endothelial Corneal Dystrophy (FECD) is a hereditary non-inflammatory corneal disease affecting the corneal endothelial cells, resulting in cellular dysfunction, corneal edema, thickened Descemet's membrane, epithelial bullae, and vision loss. CTG repeat expansion in the TCF4 gene is a well-established genetic risk factor for FECD. To determine the prevalence of CTG repeat expansion in Thai FECD patients, we recruited 100 FECD cases and 100 matched controls. Three-milliliter peripheral blood samples were collected from both cases and controls for DNA extraction. We performed the STR assay and triplet repeat primed (TP) PCR to identify CTG repeat expansion in TCF4. CTG repeat expansion with the repeat count exceeding 40 in the TCF4 gene was identified in 0.5% (1 in 200 alleles) of both FECD cases and controls. No significant differences were observed between the two groups. These results indicate that CTG repeat expansion in the TCF4 gene may not be the primary underlying factor responsible for FECD within this group of patients. It is possible that locus heterogeneity plays a role in the development of FECD, as other genes, which have not yet been identified, may be associated with this condition.