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Laboratory Sciences
January 1999

Immunolocalization of βig-h3 Protein in 5q31-Linked Corneal Dystrophies and Normal Corneas

Author Affiliations

From the Departments of Ophthalmology and Pathology, State University of New York Health Science Center, Syracuse (Drs Streeten and Qi and Ms Strauss); Duke University Eye Center, Durham, NC (Dr Klintworth); Wills Eye Hospital, Philadelphia, Pa (Dr Eagle); and Pharmaceutical Research Institute, Bristol-Myers Squibb Corp, Princeton, NJ (Dr Bennett).

Arch Ophthalmol. 1999;117(1):67-75. doi:10.1001/archopht.117.1.67

Objective  To characterize the relation of the βig-h3 protein to the diagnostic corneal deposits in the hereditary corneal dystrophies recently shown to have mutations in the βig-h3 gene on chromosome 5q31.

Methods  Corneas with lattice, granular, mixed granular-lattice ("Avellino"), and 2 types of Reis-Bücklers dystrophy were diagnosed by the histochemical and ultrastructural characteristics of their abnormal aggregates. Dystrophic and normal corneas were compared for immunolocalization of βig-h3 protein.

Results  In normal corneas, immunoreactivity for βig-h3 protein was strongest in the Bowman layer, and next strong along stromal interlamellar junctions and attachment sites of collagen to the Descemet membrane. Antibody binding was intense on all dystrophic aggregates, mimicking somewhat the normal protein distribution. Mixed granular-lattice dystrophy had the most variation in βig-h3–immunopositive forms. The aggregates in both the "rod-shaped" Reis-Bücklers type and the "curly fiber" Thiel-Behnke type were strongly stained for βig-h3 protein, consistent with mutations on the βig-h3 gene.

Conclusions  The marked immunopositivity for βig-h3 protein in the abnormal deposits in these dystrophies indicates that βig-h3 protein is a major component. The variety and quantity of immunopositive forms suggests that they consist primarily of the mutant protein, self-polymerizing and/or incorrectly binding to other corneal components. Variability of forms may relate to both the specific mutation and regional interactions of this protein.