<h4>Purpose</h4>To determine the histological differences between Fuchs endothelial corneal dystrophy (FECD) cases with and without the most common genetic risk factor, expansion of a CTG repeat (CTG18.1) within the TCF4 gene.<h4>Methods</h4>Formalin-fixed paraffin-embedded corneal tissues were compared retrospectively, and CTG18.1 status was determined from blood-derived gDNA. The gene discussed is TCF4; the disease is Fuchs endothelial corneal dystrophy.