GRHL2 and posterior polymorphous corneal dystrophy: They show phenotypic overlap with posterior polymorphous corneal dystrophy (PPCD) caused by pathogenic variants in OVOL2, ZEB1, and GRHL2 [14,15,16,17], but no genetic cause for PCVs has been identified [13], although an association with x-linked megalocornea was noted in one case [18].