TCF4 and Fuchs endothelial corneal dystrophy: Presence of toxic RNA foci in corneal endothelial cells formed of transcribed TCF4 RNA from an expanded CTG18.1 allele (n ≥ 31) is dependent on the length of both CTG18.1 alleles and considered as one of the many pathological mechanisms in FECD (Du et al. 2015; Mootha et al. 2015; Hu et al. 2018; Zarouchlioti et al. 2018; Rong et al. 2019).