It is possible that some of the 32 CTG18.1 expansion-negative cases in the Leeds FECD cohort may also carry a rare, regulatory TCF4 variant, though variants in other genes implicated in FECD, including COL8A2 [36], SLC4A11 [37], ZEB1 [38], AGBL1 [39] or LOXHD1 [40], could also account for their condition. This evidence concerns the gene LOXHD1 and Fuchs endothelial corneal dystrophy.