MedGen

Posterior polymorphous corneal dystrophy-2 (PPCD2) is characterized by formation of blister-like lesions within the corneal endothelium or by regions of endothelial basement membrane thickening with associated corneal edema. The normal amitotic endothelial cells are replaced by epithelial-like cells that possess abundant intermediate filaments, desmosomes, and microvilli. The endothelium becomes multilayered and the abnormally proliferating cells may extend outwards from the cornea over the trabecular meshwork to cause glaucoma (summary by Biswas et al., 2001). For a general phenotypic description and a discussion of genetic heterogeneity of PPCD, see PPCD1 (122000). [from OMIM]

Fuchs endothelial corneal dystrophy (FECD) is a progressive, bilateral condition characterized by dysfunction of the corneal epithelium, leading to reduced vision. The prevalence of FECD has been estimated at about 5% among persons over the age of 40 years in the United States. The vision loss in patients with FECD results from a loss of corneal transparency associated with irregularity of inner corneal layers in early disease and edema of the cornea in advanced disease. Ultrastructural features of FECD include loss and attenuation of endothelial cells, with thickening and excrescences of the underlying basement membrane. These excrescences, called guttae, are the clinical hallmark of FECD and become more numerous with progression of the disease. As the endothelial layer develops confluent guttae in the central cornea, the cells are no longer able to keep the cornea dehydrated and clear (summary by Baratz et al., 2010). Genetic Heterogeneity of Fuchs Endothelial Corneal Dystrophy More common, late-onset forms of FECD have been shown to be caused by mutation in the SLC4A11 gene (610206) on chromosome 20p13 (FECD4; 613268), in the ZEB1 gene (189909) on chromosome 10p11.2 (FECD6; 613270), and in the AGBL1 gene (615496) on chromosome 15q25 (FECD8; 615523). Other loci for late-onset FECD have been identified on chromosomes 13pter-q12.13 (FECD2; 610158), 18q21.2-q21.32 (FECD3; 613267), 5q33.1-q35.2 (FECD5; 613269), and 9p (FECD7; 613271). [from OMIM]