COL8A2

Corneal Dystrophy, Posterior Polymorphous 2

Clinical Characteristics
Ocular Features: 

This is primarily a disease of the posterior cornea although the secondary edema may extend to the epithelium.  The disease may be apparent at birth or shortly thereafter by the presence of excrescences or nodules in the endothelial layer with stromal edema.  Descemet membrane can be highly irregular in thickness.  The endothelial cells in PPCD may acquire some characteristics of epithelial cells.

Systemic Features: 

No systemic abnormalities have been reported for PPCD2.

Genetics

This is a rare autosomal dominant disorder and few families have been reported.  The mutant gene, COL8A2 (1p34.3-p32.3) is the same as that causing early onset Fuchs endothelial dystrophy (136800) and both dystrophies have been described in the same family.   The mutation alters the synthesis of alpha 2 chains, part of type VIII collagen, a major component of the Descemet membrance.

For other forms of posterior polymorphous corneal dystrophy, see PPCD3 (609141), and PPPCD1 (122000).

Pedigree: 
Autosomal dominant
Treatment
Treatment Options: 

Corneal transplantation may be indicated by the third decade or later.  The corneal lesions tend to recur, however.

References
Article Title: 

Missense mutations in COL8A2, the gene encoding the alpha2 chain of type VIII collagen, cause two forms of corneal endothelial dystrophy

Biswas S, Munier FL, Yardley J, Hart-Holden N, Perveen R, Cousin P, Sutphin JE, Noble B, Batterbury M, Kielty C, Hackett A, Bonshek R, Ridgway A, McLeod D, Sheffield VC, Stone EM, Schorderet DF, Black GC. Missense mutations in COL8A2, the gene encoding the alpha2 chain of type VIII collagen, cause two forms of corneal endothelial dystrophy. Hum Mol Genet. 2001 Oct 1;10(21):2415-23.

PubMed ID: 
11689488
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