■ Corneal dystrophies represent a highly heterogeneous group of hereditary disorders, consisting of more than 30 distinct entities, of which only 16 have their molecular basis partially or completely elucidated. The genetic characterization of corneal dystrophies revealed both genetic heterogeneity, i.e. different genes (KRT3 and KRT12) causing one single dystrophic phenotype, as well as phenotypic heterogeneity with one single gene (TGFBI) causing different dystrophic phenotypes (see below 5.5 keratoepithelinopathies).