PURPOSE: To identify the BIGH3 gene mutation in 10 unrelated Japanese individuals with granular corneal dystrophy. METHODS: Genomic DNA was obtained from each patient's leukocytes. Exons 4 and 12 of the BIGH3 gene were amplified by polymerase chain reaction and were directly sequenced. RESULTS: Nine of these patients were found to have the R124H mutation, whereas only one had the R555W mutation. Slit-lamp examination showed that the granular corneal dystrophy associated with each mutation is different. CONCLUSIONS: These results, together with our previous findings, show that the classic form of granular corneal dystrophy associated with the R555W mutation is rare in Japanese patients, whereas granular corneal dystrophy accompanied by amyloid deposits and associated with the R124H mutation, Avellino corneal dystrophy, is more common. Direct examination may be insufficient in the proper diagnosis of corneal dystrophy, and BIGH3 mutation analysis may be required.
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