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S. H. Chang, D. A. Patel, G. J. Harocopos, D. H. Thang, A. J. W. Huang; Secondary Hyalinosis/Amyloidosis in Macular Corneal Dystrophy. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4313.
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© ARVO (1962-2015); The Authors (2016-present)
To report a previously unreported finding of sub-epithelial amyloid deposits of transforming growth factor ß-induced protein (TGFBI) and hyaline deposits in macular corneal dystrophy (MCD).
Routine histopathological staining with alcian blue, Congo red and Masson trichrome were carried out on corneal sections of three unrelated cases of MCD. Non-dystrophic corneal sections were used as controls. Tissue sections were also stained with a commercial TGFBI antibody and 200 µM Thioflavin-T (ThT), a fluorescent stain for amyloid protein. Immunofluorescence sections were imaged using laser confocal microscopy.
All three cases of MCD showed alcian blue positive deposits throughout the stroma, which did not stain with Congo red, Masson trichrome, and ThT. Tissue sections from one Asian male with MCD showed prominent sub-epithelial deposits that stained positively with Alcian blue and Masson trichrome. Of significance, some of these sub-epithelial deposits also stained with TGFBI antibody. Furthermore, these TGFBI-positive deposits in the cornea also partially stained positively with ThT, indicative of the presence of amyloid aggregates. Genotyping of this index case did not reveal any mutations in the TGFBI gene. As expected, non-dystrophic corneal tissues did not show discernible TGFBI aggregates by immunostaining.
Consistent with previous reports, there is no known association between TGFBI gene mutation and MCD. However, one of our cases showed sub-epithelial deposits containing TGFBI. Deposits in this case were found to be partially amyloidogenic by ThT staining. These findings suggest that secondary hyalinosis/amyloidosis caused by non-mutant or wild-type TGFBI can occur in MCD, similar to secondary amyloidosis observed in keratoconus, Fuchs’ endothelial dystrophy, or other corneal inflammatory conditions.
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