Immunochemical classification of macular corneal dystrophy: Report of a case of immunophenotype I A in Germany

Background: Macular corneal dystrophy can be classified into three differen t immunophenotypes according to presence and distribution of sulfated kerat an 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. Material and methods: Case report of a patient with macular corneal dystrop hy type I A from Germany. Indirect immunohistochemistry for sulfated kerata n sulfate was performed on the corneal buttons obtained after perforating k eratoplasty (monoclonal antibodies 3D12/H7 and 5-D-4). The serum concentrat ion of SKS was determined using the monoclonal antibody 5-D-4 in a serum an tigen-inhibition assay. Immunogold labeling with the 5-D-4 antibody was per formed to allow ultrastructural localization of SKS in the cornea. Results: The patient demonstrated the typical clinical picture of macular c orneal dystrophy. Serum levels of SKS were not detectable. Positive immunoh istochemistry for SKS was found only within single keratocytes of both corn eae without staining of the stroma (3D12/H7 and 5-D-4). Immunogoldlabeling localized SKS within stromal keratocytes and proved this patient to suffer from macular corneal dystrophy immunophenotype I A. Conclusion: Macular corneal dystrophy immunophenotype I A can be found outs ide Saudi Arabia in a German patient. All three immunophenotypes of macular corneal dystrophy are present in corneal buttons from German patients.