In this study, we investigated if the TCF4 (CTG)n expansion (n > 40) present in the majority of FECD patients affects the mRNA expression of TCF4 transcripts spanning over the CTG18.1 repeat or transcripts with TSS immediately at the 3′-end of the (CTG)n. This evidence concerns the gene TCF4 and Fuchs endothelial corneal dystrophy.