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Two patterns of opacity in corneal dystrophy caused by the homozygous BIG-H3 R124H mutation
H Watanabe1, Y Hashida, K Tsujikawa
1Department of Ophthalmology, Osaka University Medical School, Suita, Osaka, Japan. watanabe@ophthal.med.osaka-u.ac.jp
Purpose:
To investigate the opacity pattern in corneas with an Arg124His (R124H) homozygous mutation of the BIG-H3 gene.
Methods:
Slit-lamp examination was performed on eight patients with corneal dystrophy resulting from a genetically confirmed BIG-H3 R124H homozygous mutation. The birthplace of each patient also was determined.
Results:
Slit-lamp examination disclosed two types of opacity patterns in corneas with the BIG-H3 R124H homozygous mutation. Type I (n = 4) is a spot-like opacity present in the anterior stroma in which the lesions are confluent. Type I is the same pattern that previous reports have shown to be caused by the BIG-H3 R124H homozygous mutation. The type II corneal opacity pattern (n = 4) is a reticular opacity in the anterior stroma with round translucent spaces. Type II opacity has not been reported previously in association with any corneal dystrophy. The patients with the type I opacity do not share a common birthplace; however, interestingly, the patients with the type II opacity traced their origin to Tottori prefecture in western Japan.
Conclusion:
The BIG-H3 homozygous R124H mutation induces the development of two distinct patterns of corneal opacity, the recognition of which can establish an accurate diagnosis of corneal dystrophy caused by the homozygous BIG-H3 R124H mutation independent of genetic analysis. In addition, genetic factors or circumstantial influences other than the gene responsible for the corneal dystrophy may influence the pattern of corneal opacity.