Purpose: OPA1, the gene responsible for autosomal dominant optic atrophy, represents a good candidate gene for normal-tension glaucoma (NTG). Single nucleotide polymorphisms on intervening sequence (IVS) 8 of the OPA1 gene (IVS8+4C>T; +32T>C) were recently found to be strongly associated with NTG in a Caucasian population. We investigated whether these polymorphisms in the OPA1 gene were associated with NTG in Korea.
Patients and methods: Sixty-five Korean NTG patients and 101 healthy Korean subjects were enrolled. DNA from peripheral blood leukocytes was extracted and the genotypes of two polymorphisms (IVS8+4C>T; +32T>C) in the OPA1 gene were determined using the restriction fragment length polymorphism method. The genotype and allele frequencies of two polymorphism in patients with NTG and normal controls were compared using the Fisher exact test and the chi test. Frequencies of haplotypes and haplotypes groups were also analyzed to assess the combined effect of two polymorphisms.
Results: The frequencies of the CT genotype of IVS8+4C>T, CC genotype of IVS8+32T>C, and TT genotype of IVS8+32T>C were not significantly different between NTG patients and controls (4.6% versus 0.0%, P = 0.058 by the Fisher exact test; 10.8% versus 4.0%, P = 0.11 by the Fisher exact test; 61.5% versus 67.3%, P = 0.45 by the chi test, respectively). Any haplotype or haplotype group of IVS8+4C>T and IVS8+32T>C was not associated with NTG, and the C allele of IVS8+32T>C was not a significant modifier of IVS8+4C>T.
Conclusions: There were no significant associations between IVS8+4C>T; +32T>C polymorphisms and NTG in the Korean population. These results do not support the results in Caucasians and indicate that ethnic differences may exist in the association between polymorphisms in the OPA1 gene and NTG.