Unilateral or bilateral isolated cryptophthalmos (CRYPTOP) is a rare congenital disorder characterized by ocular dysplasia with eyelid malformation. It has been reported that mutations in FREM2 cause isolated cryptophthalmos. FREM2 is a member of the Fras1/Frem protein family that directly interacts with constituents of connective tissue through their chondroitin sulfate proteoglycan motifs, contributing to epithelial-mesenchymal coupling.
