In Finland, the TCF4 (CTG)>50 expansion is a significant risk factor for FECD. A nearby single-nucleotide polymorphism (SNP) was found to perform well as a surrogate for genotyping. However, not all patients carried the expanded repeat, and a variant in a previously associated gene was observed in a single patient. Further research is needed to investigate the origins of FECD in individuals without the repeat expansion.
Vähämäki et al. (Mon,) studied this question.