KRT3 and Meesmann corneal dystrophy: All known MECD mutations in KRT3 and KRT12 consist of dominant-negative missense mutations (or one small in-frame insertion) that occur in either the helix initiation or the termination motifs (www.interfil.org, 15 October 2015, date last accessed) that fulfil a critical role in the early stages of filament assembly (34).