Ocular Pathology

Anatomy and pathology of the human eye. Use it to review eye pathology for Ophthalmology Board Review or OKAP.

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Saturday, September 30, 2006

TGFBI Corneal Dystrophy- Avellino Phenotype

Transforming Growth Factor Beta Induced Gene (TGFBI) Corneal dystrophy
Definition: TGFBI also known as BIGH3 may have a number of phenotypes. The lattice phenotype shows deposits indicative of amyloid deposition without a red color upon trichrome stain. The Avellino phenotype shows both characteristics. In fact the gene defects encompass the same gene and the protein sequence of keratoepithelin is similar if not identical.
Etiology:Features of both granular and lattice dystrophy appear in Avelino dystrophy, first described in patients tracing their ancestry to Avellino, Italy. Histologically, both hyaline deposits (typical of granular dystrophy) and amyloid deposits (characteristic of lattice dystrophy) are present within the corneal stroma. This dystrophy, like granular and lattice dystrophy, has been mapped to chromosome 5q.

Histopathology: The cornea shows stromal linear deposits (arrow 1) that are present similar to lattice dystrophy as well as discrete intrastromal deposits (arrow 2) that appear white in gross specimen on cross-section. All of the deposits stain similarly. Trichrome stains the deposits bright red. The fluorescent dye Congo red binds to the protein and exhibits dichroism (circular and linear) with a Cotton effect as well as optical rotary dispersion.


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