Immunophenotype classification of macular corneal dystrophy: first case report of immunophenotype I A outside of Saudi Arabia. A clinical histopathological correlation with immunohistochemistry and electron microscopy

Abstract

Macular corneal dystrophy can be classified into three different immunophenotypes according to presence and distribution of sulfated keratan sulfate (SKS) in the cornea and serum levels of SKS. Immunophenotype I A has yet only been reported in patients with macular corneal dystrophy from Saudi Arabia. Case report of a patient with macular corneal dystrophy type I A from Germany. Indirect immunohistochemistry for sulfated keratan sulfate was performed on the corneal buttons obtained after perforating keratoplasty (monoclonal antibodies 3D12/H7 and 5-D-4). The serum concentration of SKS was determined using the monoclonal antibody 5-D-4 in a serum antigen-inhibition assay. Immunogold labeling with the 5-D-4 antibody was performed to allow ultrastructural localization of SKS in the cornea. The patient demonstrated the typical clinical picture of macular corneal dystrophy. Serum levels of SKS were not detectable. Positive immunohistochemistry for SKS was found only within single keratocytes of both corneae without staining of the stroma (3D12/H7 and 5-D-4). Immunogold labeling localized SKS within stromal keratocytes and proved this patient to suffer from macular corneal dystrophy immunophenotype I A. Macular corneal dystrophy immunophenotype I A can be found outside Saudi Arabia in a German patient. All three immunophenotypes of macular corneal dystrophy are present in corneal buttons from German patients.